Thanks to Dan Stauft for this information.
QUESTION: How do you reset the Change
Engine Oil light?
ANS: 1. Turn key to run, but do not start the car.
2. Press ENG MET on the trip monitor, then within 5 seconds, press it again.
3. Within 5 seconds, press and hold GAUGES on the trip monitor. The CHANGE
OIL light should flash.
4. Hold the GAUGES or RANGE button until the CHANGE OIL light stops flashing
and goes out. This should take about 10 seconds.
QUESTION: Do after market chips
really make a difference?
ANS: I think we should first discuss basics here, because I think most of
these "chip" discussions are more involved with "mine's better than yours", etc.
than realistic expectations. The power production of our engines is a function
of many factors, but a few basics dominate. The first and most important factor
involves how much air the engine can pump. This is the part of power production
that gets most of the attention. Hear me now and believe me later, "more mass of
air moved equals more horsepower."
Naturally, the biggest part of this is the actual displacement of the
engine. Consequently, everything else being equal, bigger is better. (The
builders of the Viper took this one to the bank!) In the same vein, everything
else being equal (hard to achieve) higher RPM is better. If volumetric
efficiency were constant at all speeds, obviously higher speeds move more air.
This brings up the other main area of concern with increasing the mass of
air moved - volumetric efficiency. This is where most people spend most of their
effort. This encompasses air cleaners, ducts, head flow, valve sizes, exhaust
systems, cam profiles, etc. Some of these areas affect air flow at all speeds;
others, e.g. cam profiles favor specific RPM ranges. Again, in all these areas
increasing the mass of air flow is the objective since it is directly related to
power. Of course, the ultimate in volumetric efficiency is to be greater than
100%. That's exactly where supercharging and turbocharging comes in.
Factors other than increasing mass air flow that are related to power output
include compression ratios, combustion dynamics and parasitic losses.
As far as calibrations go, they are only involved when they're wrong. In
other words, having precisely the optimum air-fuel ratio is of minor importance.
Having the optimum spark advance is of more consequence. However, getting both
of these right is not difficult and doesn't vary substantially with the other
elements mentioned above. Consequently, with computer controlled systems as used
in the LT5, a fairly wide variation of engine basics can occur and the engine
will still be very close to optimum full throttle fueling and spark advance.
Therefore, for full throttle power the prospect of magic increases through
calibration changes is unlikely.
Thanks to Jim Ingle from GM Power Team for the above information.
QUESTION: How come I can't purchase
an original ZR-1 battery?
ANS: It seems that the original battery (75Z-72) has been discontinued by
AC-Delco, General Motors and the authorized "upgraded replacement" is now
(75B-84). This replacement battery is a Delco Freedom 84 series battery and is
warranted for 84 months from the date of purchase as compared to 72 months for
the original. It also has an increase in CCA (Cold Cranking Amps) of 735 CCA as
compared to the original 690 CCA. The new battery is noticeably heavier, has a
black case, and raised reinforcement ridges on both ends. The label is slightly
different in color & number, but all else is the same.
From ACDelco:
The correct battery number, with the eye at the opposite end, is battery number
75A-72. Part number 75Z72 has been discontinued.
Thanks to
ACDelco Customer Assistance for
this info.
UPDATE 1/31/00: A newer battery has been introduced for the ZR-1, 75-7YR.
The hydrometer eye is placed in a standard position on the 75-7YR replacement
battery. The hydrometer is not a method to check the wellness of the battery.
The hydrometer eye is only an indicator to see if your battery is ready for a
load test. For a load test to be performed the battery would be disconnected and
not in the vehicle, thus allowing the hydrometer eye to be viewed.
QUESTION: I bought a '90 or '91 and I
didn't get an owners kit? What is in this owners kit?
ANS: For '90 and '91 GM had a "special" ZR-1 Customer Kit created. It was
mailed to the original owners (car registered to) name/address after purchase,
but only went to US customers.
The kit came in a vinyl wrapped box with the ZR-1 logo and is the size of a
pizza box, only higher. Inside it contained:
1- A duplicate window sticker.
2- A Leather portfolio with ZR-1 logo and a metal tag with your vin number and
or name/vin number.
3- A Photo album/coffee table book (90 and 91 were different).
4- Video tape, again different for 90 and 91.
5- A ZR-1 specific owners manual with ZR-1 logo.
6- A Brass Key ring with ZR-1 logo.
On the open market these can sell from $300 to $1,000.
Click here to see a picture of a 1990
owners kit.
QUESTION: Are there any options that
are rare on a ZR-1?
ANS: There were really only two options, electronic climate control and dual
roofs. The electronic climate control was drop as an option in 1991 and became a
standard. Very few '90 ZR-1's were delivered with manual climate control. Rumors
were around 14 ZR-1's had manual AC.
Something unusual happen in the 1992 model year. An option that was standard
in the RPO ZR1 package was dropped 1/2 way though the 1992 year. The power
passenger seat AC1 which had always been packaged into the ZR1 option was pulled
and had to be ordered separately.
In 1993 GM once again included AC1 as part of the RPO ZR1 option.
Not an option but early '90 ZR-1's had steel 1/2 shafts in the rear vs
aluminum on all others.
QUESTION: I'm getting noise over my
radio?
ANS: There could be several reasons for noise over your radio. Here are a
couple of problems that ZR-1 owners have found and corrected.
The noise/squeal described is exactly what my 90 did, first to the right rear
speaker/amp then to the left rear speaker/amp. When the right rear finally
failed (Yes you could turn the radio off/on and the noise would go away but it
finally completely failed) I took the assembly out (3-4 screws and a disconnect)
and took the amp apart. It was obvious the amp was bad as you could see where
the circuit board had gotten hot and the power transistors were fried.
The Delco/Bose systems installed in 90 and up Corvettes apparently are prone
to a failure in the rear speaker amps. The problems first appear as a loud
alternator wine and popping that seems to come from the whole system rather than
any one speaker and at first you can turn the system off then on and it will
sometimes go away. To troubleshoot you can disconnect the rear speakers one at a
time to find the problem. This involves using a screwdriver to remove the
speaker covers and disconnecting the wires that come from the radio. After
finding which side is bad you can remove the speaker assembly using a 7MM
socket. The amp will have one of the following part # 16148750 or 16148752. I
have tried various parts houses but these #'s listed as a back order item that
nobody had seen in years and were doubtful about getting. They also listed the
following as the latest replacement # that they could order 16179367 which has a
dealer list of $354 a dealer cost of $285. Since the first #'s are not available
I talked to Hamp at Speedometer Service in Atlanta Ga and he will ship at dealer
cost to those who are in need. His phone is 1-800-241-2385 and he will take
VISA/Master. If I get any other information I will post it. Hamp is very
knowledgeable on these systems and does rebuild dash units as well as the
radios.
Another possible problem could be an alternator. A "high-pitched whine"
suggests possibly alternator produced noise. And the note that it goes away with
the engine off relates to that possibility as well. Alternators can deteriorate
to produce RF (Radio Frequency) emissions while continuing to function
otherwise, so that may be related. Another whole class of problems with cars
relates to "ground faults". If there is a poor (high resistance) path to ground
of the radio, it can result in performance loss. A quick check is to temporarily
run a wire from the radio case to ground (preferably the battery ground
terminal) and see if it affects your problem. If so, consider some more
permanent arrangement. Finding and repairing poor original equipment grounds can
get messy. I believe the Service Manual Electrical Section shows ground points,
so it may be worth referencing (if you have access to one).
Other sources for radio parts:
-Baker Automotive has the unit you're looking for. Call Kim Baker for prices
at 413-596-9475. Baker is a race car driver, so his "used" parts are actually
removed from new Vettes he gets and converts to race cars.
-Buy a used one out of a wrecked Vette from Roy Landrum Enterprises-
606-586-6218 - Office 513-535-8688 - Mobile
-Contact United Radio in NY. 1-800-448-0944 They Do a lot of warranty work
for GM
-Brad's Corvettes - via internet at
bradscorvettes@flinet.com Price was $100
for speaker and amp.
-C&S Corvettes - 1-800-886-5064. $120.
-Vette Wrecks - 1-800-462-0123. $150
- Contemporary Corvette (advertises in Corvette Fever and Vette). $75
- America Corvette in Atlanta just received 500 new amps. They also purchased
new speakers, and radios. They are selling the amps for $60.00 a piece, that's
correct $60.00 new. These amps are also higher output, 50 watts vs 30 watts
stock.
You can call Jim Bressner at 1-800-377-6793 to order.
Past and Present Automotive in Clearwater Fl 813-535-7288 will repair all Bose
speaker amps.
Another member this with his amps.
Several people on the net have expressed a desire to learn more about repairing
the Bose speaker amps.
There are probably six or seven manufacturers of small electronic capacitors in
the world (just a guess). One of the companies apparently manufactured poor
quality parts in the 1988-92 era. Time and humidity cause the capacitors to leak
electrolyte and fail after a couple of years.
I have a 1989 Toyota Supra and the stereo went bad a couple of years ago. The
stereo in my sister's '89 Supra also went bad, as did the stereo in a friend's
'91 Supra and all of the Supras made during that time period. I took my Supra to
a radio repair shop and the guys were intimately familiar with the problem -
leaking capacitors. The fix was to replace the capacitors.
When the left rear speaker in my ZR-1 recently quit working, I called a local
repair shop. They have been very busy the past couple of years repairing Bose
amps. The problem is... you guessed it - bad capacitors. My Corvette is a '90
model and Bose apparently bought capacitors from the same manufacturer that
Toyota's stereo supplier, Fujitsu, did.
There are eight small green colored capacitors in each rear amp that look like
miniature Sprite cans. I replaced them all. They are all high temp (105 C) mini
radial electrolytics with various capacitance and voltage values. You can get
these at a large electronic supply store for $.50 to $.75 each. I bought mine
here in Houston at Electrotex (713) 526-3456. If you have never desoldered and
soldered anything before, find a friend who has and learn from him. Capacitors
are polar, so make note of where the positive and negative sides are connected
to the board before removing the old capacitors so that the new ones may be
installed correctly. The negative side of capacitors is marked with a
longitudinal band.
After the replacement, I reinstalled the amp in the beast and the speaker now
plays perfectly.
Some people have posted on the net that they believe the amps fail due to heat
buildup destroying the power transistors. I have heard that the failed boards
have brown spots on them with is assumed to have come from overheating. My
observation was that the board became discolored (brown) where it was contacted
by leaking electrolyte from the capacitors. Anyway, since I have heard that the
new style amps have a larger heat sink area than the old style, I exercised
precaution and applied some white dielectric heat conducting grease to the two
power transistors where they contact the metal cover. The stamped sheet metal amp
cover serves dual duty as a RF shield and heat sink. By the way, the high temp
capacitors are made to withstand 105 degrees C, which is pretty darned hot.
Thanks to William Barrett for this info.
FROM AMP OPTIONS:
We at Amp Options have a product you might be interested in. We have developed
an amp to replace the Bose* type amp in car stereo's 84 and up with minimal
install hassle. In fact, with 91 and up simply remove bad Bose* type amp and
plug our amp in. Pre 91 requires chopping of the wire harness and connecting
with a connector supplied by us. Each amp is built and tested in the USA and
comes with a two year limited warranty. Amps come in a box of twelve at $79.95
per amp, connectors are $3.29 apiece and also come in a box of twelve. Each amp
is individually boxed and comes with instructions on installing the product.
Every amp comes with a gain adjustment to synchronize the volume with current
factory amps still in the vehicle. Any order $2,000.00 or more is shipped
prepaid. If you would like to deal in volume please contact me to discuss the
price further. Thank you for your time, if you have any questions or comments
contact me at:
e-mail at: loki251638@aol.com
or call between 8:00 AM to 9:00 PM EST at 770-638 0359
Sincerely,
Michael Knoll
Factory Representative
QUESTION: I'm hearing a strange
rattle sometimes at certain RPM's?
ANS: It's always difficult to describe noises and to understand what the
description means. A possibility is a rattle from an exhaust system heat shield.
You may have a loose, missing or broken fastener or the part may have shifted
such that it's contacting another part. These rattles tend to be very "peaky" so
they occur in a very small RPM window.
Another possible reason could be the dual mass flywheel. The dual mass
flywheel is just what the name implies. It's two flywheels connected by a spring
damper system. The engine crankshaft bolts to the forward flywheel and the
clutch attaches to the rear one. It does not change position with speed but it
does "wind up" with torque. It's purpose is to control transmission gear rattle.
Replacing the flywheel with a conventional single mass flywheel will result in a
very high level of gear rattle.
QUESTION: I'm getting a squeal from
my clutch?
ANS: The problem you're most likely experiencing is a noisy crankshaft pilot
bushing. There is a later design released for service that tends to retain
grease better than the one you have and therefore doesn't squeal when cold.
Unfortunately, the transmission has to be removed to access the bushing, so it's
not a minor repair although the part cost itself is trivial.
In the event you're not familiar with these parts, the input shaft to the
transmission is externally spined to connect to the inside spine of the clutch
disk. The forward tip of the transmission shaft is a smooth section that is
located radically by the bushing in the end of the crankshaft. When the clutch is
engaged (foot off the pedal) the transmission input shaft turns with the
crankshaft, so there's no relative motion. However, when the clutch is released
(foot on the pedal) such as when you're at a traffic light, the transmission
shaft is not turning and the crankshaft is. This is when the squeal would occur
with a dry bushing.
The new bushing has grooves in it to help it retain grease and it seems to
have solved the problem.
Thanks to Jim Ingle for his input.
QUESTION: How can I tell either the
coolant temp or oil temp from the analog gauges?
ANS: See chart below:
Percentage
of Scale |
LT5 Oil Gauge
READING | ACTUAL |
Coolant Gauge
READING | ACTUAL |
| 0 % |
100 deg F | 100 deg F |
100 deg F | 100 deg F |
| 25 % |
-------- | 191 deg F |
-------- | 184 deg F |
| 50 % |
-------- | 220 deg F |
-------- | 210 deg F |
| 75 % |
-------- | 246 deg F |
-------- | 232 deg F |
| 100 % |
280 deg F | 280 deg F |
260 deg F | 260 deg F |
Thanks to Gordon Killebrew for the chart.
QUESTION: My ZR-1 runs hot, anything
I can do to improve this?
ANS: For some applications it is known that the stock ZR-1 cooling system has
proven to be inadequate. This has been born out through observations by many
individuals on the ZR-1 Network. Various options have been explored with one
option, two suppliers, proving the be the most viable fix to over heating.
The larger radiator from Doug Rippie Motorsports and the unit from
Lingenfelter Performance Engineering both have proven themselves to be very well
made pieces of equipment. They do an excellent job at keeping engine
temperatures in a very comfortable zone under the most extreme conditions of
operation. Typical operating temperatures run in the 90c-97c range, the upper
end under track conditions. This is well below the 112c temperatures witnessed
by several people.
With many members of the ZR-1 Net having installed one of these units, not
one disparaging remark has been made, only glowing reports. We all highly
recommend one of these units in addition to a Doug Rippie modified thermostat.
In bang for your buck, this is one of the best values you can possibly do.
Thanks to Jim Milstead for this information.
More important for proper cooling, is a clean and unobstructed radiator, and
possibly a modified prom calibration. Take a half day and remove the top shroud
of your radiator from the top. Look down in between the AC condenser and the
radiator and you'll be shocked. If car show judges could find a bent up mirror to
get down in there, all you waxers would be in misery! It's filthy! As Corvettes
are bottom feeders, we've found that the radiator's airflow is severely
obstructed in many cars. This is not visible from the bottom but sometimes you
can see a little through the oil cooler line cut outs in the passenger side of
the shroud. We've also made a pipe that screws onto a hose that is about 3
feet long. At the end, we put a 90 deg. elbow. After the shroud is removed, this
pipe can be used to "reverse" flush the radiator fins with water. This will
help. Just for info: We've also found that most ZR1's out here in furnace land
will gradually start overheating after 3 to 4 years no matter what. With the
addition of a new radiator, they run cooler than ever. Adding a Stant t-stat and
recalibrated prom helps even more.
Also the stock cooling fans were manufactured with several air holes in the
case. Wet climates or washing the shroud area will allow water to settle within
the electric motor. Along with dirt and dust, this causes the motors to get weak
over time. The new motors, part number 15-8484, do not have any breather holes
and are a sealed unit which eliminates this problem. In addition, I believe they
turn more RPM's.
You'll also want the new blades 15-8468 which flow much more air than stock.
Thanks to Jim VanDorn for this info.
More on cooling........
There is a coolant bypass device in the stock ZR1 cooling system which does
compromise the cooling ability of the package, the same is true of the oil
cooling system. My recommendation is to install an aftermarket radiator with
sufficient flow capacity to cope with the 100 USGPM that the water pump is
capable of. But I would strongly advise against altering the pressure setting of
the radiator since the system is very sensitive to pressure variation. The
typical failure mode with either too little or too much pressure is material
erosion in the pump itself (caused by cavitations) and also in the cylinder liner
and seat areas caused by nucleate boiling. Which is basically small pockets of
super heated coolant near the metal surface flashing to steam and eating away at
the part in question. During its development phases the LT5 was run at several
dyno facilities other than Lotus, each time we had to ensure the correct
parameters for the cooling system or holes would appear in the early running
life of the engine. So if you wish to change the system pressures be warned,
puddles of coolant may be prone to appearing on the floor and/or the oil level
in the pan may rise.
In so far as the oil cooler is concerned, the stock unit is not capable
of dealing with the heat rejected to the engine oil at sustained high
speed operation, no matter when the waxstat opens. So fit a cooler that
is and then it doesn't matter where the stat opens since the cooler is
capable of coping with the heat rejected by the engine. If people insist
on earlier opening of the oil cooler lines then simply buy and fit a
lower temp waxstat, since the unit is pretty similar to many water
thermostat devices, this should not be too hard to find. Furthermore
there is a constant controlled leak across the valve to ensure that
cooler opening in extreme cold conditions does not result in oil
pressure loss due to the cold slug of oil being pushed into the engine.
P.S. the amount of power to coolant flow rate was 4bhp to 1 gpm as a rough rule
of thumb.
Thanks to Graham Behan of Lingenfelter for the above info.
QUESTION: I need to touch up my
'94/'95 wheels, what color paint do I use?
ANS: Go to your local hobby store the one that sells plastic models, and get
a paint that is made by Tamiya. Its called Tamiya color, Acrylic Paint and the
code number is X-11 (chrome silver). Don't worry about the color (chrome sliver)
when it dries its the exact same color as the wheel. Just remember to stir the
paint and do not shake it.
Touch up the ding with a small soft brush filling the ding to just higher
than the surface of the surrounding paint. Let dry for 24hrs then lightly buff
down with some polishing compound to the same surface level of the rest of the
paint. Be sure that the wheel is cool before attempting to touch it up.
Thanks to Pete Bordonali for this info.
Another member has found Testors #1181 Aluminum FLAT ENAMEL in the little tiny
bottle (like kids and dads use for model airplane building). It is very close
and looks great. And it's cheap - $1.10 at Michaels craft stores. It makes the
outside wheel weights almost disappear too.
Thanks to Randy Schulkers for this info.
QUESTION: I'm having problems with my
INFL REST light coming on.
ANS: Well, it seems as if all us 90 owners have experienced the famous "INFL
REST" problem. I have also had the problem, and in my case I was able to fix it
for free. Mine was a code "25" which is a "Front Sensor #2 (RH); Open Circuit".
The most likely reason for this failure is corrosion under the sensor. The
reason for the corrosion is AC accumulator run-off. The water drips down from
the accumulator and runs down the frame rail to the sensor. It wicks under the
sensor, and corrodes the bolts and holes. This opens the connection to ground,
and creates the error #25 condition. Mine goes out each summer (when I'm using
the AC) and I have to re-clean the connection. Here's the procedure to fix.
1. Read the stored codes. (They remain, even after a battery is disconnected)
1a. Turn ignition switch to "Off". 1b. Ground ALDL terminal "K" to ground ("A").
Consult the manual pg. 9J-A-3 for picture of ALDL connector. (Too hard to
explain)
1b. Turn ignition switch "On".
1c. The flashes of the "INFL REST"
indicator lamp correspond to the digits of the two digit malfunction codes. Code
12 will be displayed three (3) times, followed by any other codes, which may be
stored. Each code will flash three (3) times. After all the codes are displayed,
the sequence starts over with "12" again. If you have a code "25", you can
proceed. Here is a total listing of all the codes;
14 Front Sensor #1 (LH); Short to Ground
15 Front Sensor #1 (LH); Open
Circuit
16 Front Sensor #1 (LH); Sensor Fault
24 Front Sensor #1 (RH); Short to
Ground
25 Front Sensor #1 (RH); Open Circuit
26 Front Sensor #1 (RH); Sensor
Fault
31 Inflator Squib; Current leakage to Battery
32 Inflator Squib; Current
shorted to battery voltage
33 Inflator Squib; Current leakage to ground
34
Inflator Squib; Current shorted to ground
35 Inflator Squib; Open circuit
36
Inflator Squib; Squib fault
41 Indicator lamp circuit; Shorted to battery or
ground
42 Indicator lamp circuit; Open circuit
51 Diagnostic unit faulty
52
Firing sequence confirmation set
53 Firing current confirmation set
54 Squib
current has flowed
2. Disconnect the battery. (You don't want the SIR to fire when your
working) You should also wait 30 minutes after disconnecting battery before
working any SIR problem.
3.Remove the passenger side front tire.
3a.Remove the
rear inner wheel well. It has an assortment of Torx and hex head bolts.
3b. You
will now be able to see the sensor, which is mounted on the frame rail. (It is
located towards the back of the wheel well area. The box is around 2x3".
3c.The
sensor has 2 different bolts securing it. (13mm and 10mm I think). Remove them
(Yes, it's is very hard to get the rear one out).
3d. Carefully work the sensor
forward out of its position. The cable has some slack, and will allow a few
inches of movement. It is just enough to get the sensor up out of the way, to
allow for cleaning.
3e. Once removed, you can clean up the surface and apply some
dielectric grease to the surface to keep the water out. Make sure you clean both
the frame and the sensor. Mine was very wet and greasy. The main grounding comes
from the bolts, so make sure they cleaned up. If the bolts show a lot of
corrosion, replace them.
3f. Carefully reassembly everything. The back bolt again
will be a real bear.
4. Re-connect the battery.
5. You must now clear the codes.
(You may want to try this first, as the water may have evaporated. Sometimes my
codes will go away for months, after simply clearing the codes.
5a.Turn ignition
switch to "Off".
5b.Ground ALDL terminal "K" to ground ("A"). Consult the manual
pg. 9J-A-3 for picture of ALDL connector. (Too hard to explain)
5c.Turn ignition
switch "On".
5d.The codes will flash as before.
5e. Wait for the fault codes
to flash. (Approx. 5 seconds). When they do, unground ALDL terminal "K" for 3
seconds +/- 1/2 seconds. (The timing here is critical, and you may have to try a
couple of times). After ungrounding; ground it again for 3 seconds +/- 1/2
seconds. Unground again and wait 10 seconds.
5f.Code 12 should now be the only
fault. If not, redo section 5 again.
It has been a while since I have performed this procedure, so use at your own
risk.
Thanks to Mike Zeeff for this information.
QUESTION: What happens if I remove
all my Low Tire Pressure sensors?
ANS: For the 1990 and 1991 ZR-1's nothing. You will not see any error
indications on your dash. It'll be as if you never had the LTPWS option.
For 1992-1995 ZR-1's your LTPWS error light on your dash may light. Telling
you your system has malfunction. Whenever you remove all 4 wheel sensors you
will get a code 99. It may not appear right at first and can go up to 200 miles
before it turns the light on and sets the code, but it will happen. There are
two things that can be done and both require removing the DIC.
One is to remove the 2 lights in the upper right hand corner of the DIC and the
other is to unplug the module. This can be done by using a hook to fish the
connector out to where you can unplug it.. The module is attach to the right
side of the speedo cluster and can be seen through the hole behind the DIC. It
has a pink wire and a black wire going to it, after 91 there is a third wire,
tan.
The easiest thing to do is to remove the DIC and remove the 2 light bulbs or you
can also remove the cruise control fuse, which will also disable illumination of
the LTPWS lights; of course, that option disables the cruise control function.
Thanks to Jim VanDorn and Jerry Watts for this information.
QUESTION: Sometimes I have problem
with my ZR-1 not starting.
ANS: Could be one of several problems.
1. The VATS system.
2. A starter problem.
3. The clutch safety switch.
For number one, VATS, a quick way for a technician to diagnose a VATS problem
is to hook up a Tech 1 scanner. When the vehicle fails to start, display the
VATS parameter and note what it says. If it says "VATS enabled" then you've
tripped the VATS system and have eliminated other possibilities. This will reset
itself after 5 minutes provided NO OTHER ATTEMPTS TO START, OPEN DOORS, ETC
OCCUR. A common cause of the VATS problem is the ignition cylinder, which has
been updated. If this occurs, change to a new (spare) key and try it. Also, if
the VATS system is the problem, try unlocking the driver's door with the door
key a couple of times. As most of you already know, the door key switch
deactivates the UTD alarm and this switch is known to go out after time (it's
obviously the most used).
Also note if the security light is on while trying to start the ZR-1. If it is
then it's your VATS system. Also if you wait 15 minutes and then try to start it
and it starts that also says it is your VATS system.
From Jerry Watts: If the ccm sees the wrong resistance or no resistance when
the key is turned to the start position it will set a code 54. Any time there is
a ccm code that is active your cluster will flash. If the vats system fails, it
will not turn on the fuel pump when you first turn the key on, this you should
be able to hear; also you could not push start the car because of no fuel and
the injector will not be pulsed.
For number 2, the starter, the most probable problem is that your starter has
gotten wet. Have you rinse down the engine lately? If it is the starter, then
you should be able to park it on a hill and turn it off, try the starter and if
it doesn't start, then jump start it by rolling a little. This eliminates the
PASS Theft deterrent system and leaves either the clutch safety switch, or the
starter itself.
From Jerry Watts: G.M. issued a bulletin back in October of 92. While working
at the action center we received a lot of calls concerning this problem. If you
wash your engine or are in a high humidity area the starter can corrode because
of its location. Later the drain hole size was increased to help with this
problem but, it was found this was not a 100% cure. The starter can be taken out
and cleaned and put back if you wish.
For number 3, clutch safety switch, to check the clutch safety switch use an
ohm meter to make sure the switch is opening and closing right or the real fix
for this problem is to remove the switch, re-crimp the wire connectors going to
it, then re-install the switch. In many cases this should fix your starting
problem.
Thanks to Jim VanDorn for this information.
Note: From another member on checking clutch switches. There is an easy
way to check the clutch safety switch, assuming the starter isn't starting. Set
the parking brake, put the shifter in neutral, and watch the voltmeter while you
turn the key to the start position. The voltage will drop slightly. While
holding the key in start , release the clutch pedal. If the voltage goes up and
down in response to clutch pedal movement, the clutch switch works.
QUESTION: The feeling of loss power
under heavy acceleration.
ANS: There can be several reasons for the feeling of loss power. One is the
collapse of the air duct. But another possible problem as written by one of our
members.
Since we are on the "loss of power" subject I thought it might be helpful to
share an experience that I had a couple of months ago. I also experienced "loss
of power" under heavy acceleration - she (LT5) just won't hookup. In addition, I
also heard a "moaning" kind of noise that really sounded like a vacuum leak. So
my mechanic, spent a couple of weeks, off and on, chasing the vacuum problem. He
ended up replacing all of the vacuum hoses, tubes and MAP sensor, even those
under the plenum.
None of this helped and the problem persisted. We did notice
something, though, that when he pulled the plenum and looked at the secondaries
it looked like they had not been operational in a while. As a last resort we
called Jerry Watts and Gordon Killebrew. Yes, they diagnosed the problem -
damaged fuel pump. Many thanks to the guys.
Solution: (or my understanding of it) The computer had damaged one of the two
fuel pumps and therefore the engine was starved for fuel under heavy
acceleration. Hence the loud sucking "moaning" sound. So my mechanic replaced
the computer and fuel pump. Guess what.......yep, no more problem. Now she runs
like new.
Thanks to Lauren Groth for this information.
Also on hard high speed turns like on the track you may feel a lost of power
which can happen if your fuel tank is less than half full.
QUESTION: How many 1990 ZR1s were
shipped with manual AC (C60)?
ANS: A total of 124 1990 ZR1s were built with Manual AC (C60). After 1990
Electronic AC (C68) became the standard.
QUESTION: Can the surface of the
flywheel for a ZR-1 be machined?
ANS: The flywheel cannot be machined on the LT5. Get another flywheel and
also order the weight kit (which nobody knows about at the dealer) for balancing
purposes. You will need to look at your present flywheel and note where the
weights are placed in the holes at the outer edge. Insert the new weights in the
matching holes of the new flywheel.
Thanks to Jim VanDorn for this info.
QUESTION: Why is the cost for the
valve cover emblems so expensive?
ANS: Nobody knows, but the 1990 emblems are around $22.00 while all other
years are around $125.00. The 90 emblems had a red background behind the bowtie
(84-90 emblem) while 91-95 had a black background.
QUESTION: I understand there is a
build sheet somewhere on the ZR-1?
ANS: Yes in maybe two places. One on the fuel tank and one in the left front
suspension area of the ZR-1.
First the tank sheet and build sheet are the same. It's basically a computer
generated birth certificate for your car. It has the date/time built (actually
its the date the sheet was printed) all the RPO codes, their explanations, and
shows all your codes for the suspension components, seat belts, air bags,
colors, dealership, the whole works.
I've never found one on the interior of a late model, but getting the tank
stickers off is not difficult.
Start by removing the spare tire and tray from underneath the back of the
car.
Lay under the car and look between the gas tank and the vertical piece of
fiberglass where the rear compartment is. You will see the tank sticker the
tank, you can gently remove the paper from the adhesive. How much glue is there
depends on how good a mood the guy at the plant was in that day. I've seen some
with virtually NO glue, to some that were completely glued on. Sometimes, on
some prototypes I've seen, the guys would get cute and write "ZR-1" in the glue.
Usually, ZR-1 is written across the sticker in Red marker. Maybe you will get
lucky and have had someone at the plant leave a personal note on the sticker.
"Kick Ass" and "King of the Hill" are popular themes.
It is definitely worth going after.
If that sticker is missing for some reason, and you really want to know.....
This is supposed to be a secret, but I was never charged with guarding it, so
here goes....There are additional copies of the build sheet in the left front
suspension area of the car. I'm going to take a closer look at one of the '89s
later, but I think if you remove the lower A-arm, and maybe the spring on the
drivers side, you can retrieve it. The paper is inside the cross member where it
is bolted to the frame. A really bright flashlight will allow you to find it by
looking into the oval holes in the cross member from the top (near the motor).
You will see the paper in the hole, then you can figure out how to get to it.
The only one's I've ever retrieved were by dropping the cross member, but its
probably possible to do it without so much disassembly.
Thanks to Ed Simmons for this information.
QUESTION: How good is the clear coat
on my wheels?
ANS: After working for an OEM aluminum wheel supplier in the capacity of
production engineer in charge of the paint process, I can possibly lend a bit of
light to the clearcoat durability issue. This problem is not in any way specific
to either GM or Corvette, it is an industry wide problem that is being addressed
in different ways by the different manufacturers.
As a side note, the company that I worked for supplied wheels to GM, Toyota,
Mazda, Ford, Nissan, Subaru, and a few other companies. Of all of the companies,
GM took the most aggressive approach to solve wheel durability problems found
over the last 7 years or so.
SOME PROBLEMS:
1. Wheels are in the worst possible environment for paint. They get banged
up, cut by wheel weights, go through outrageous temperature fluctuations (32
degrees out, you slam on the breaks in a panic stop, wheels jump 100 degrees or
so in a few seconds, paint stresses as a result), and get hot brake dust spewed
at them constantly.
2. Aluminum can be a bitch to paint, especially when the paint is a clearcoat
over the machined surface. As you may know, water beads up on aluminum (it is
not a really wetable surface). Paint also wants to bead up on the surface -
this would be bad. To coerce the paint into sticking to the aluminum, a
conversion coating must be applied. The most durable clear conversion coating is
chromium chromate (not to be confused with chrome plating). A basic paint
process is as follows: A wheel is sent through a pretreatment system (industrial
washer) where it is cleaned with an alkaline detergent, rinse, converted either
by spray or immersion in an acidic bath composed of chromic acid, accelerators
(fluozirconic acid, for one), and etching agents (hydrofluoric acid, for
example), sent through a series of counter flow rinses (each rinse is fed from
the following stage), and finally rinse with pure deionized water to eliminate
spotting. After all of this, the wheel is clear coated with either a solvent
acrylic clearcoat (i.e. Japanese suppliers) or powder - polyester or acrylic -
clearcoat.
3. The durability adhesion (paint film resistance to peeling from a scribe
line after being introduced to a corrosive environment) tends to improve with
both higher levels of the chromium conversion coating. The problem with this
scenario is that the conversion coating tends to turn green or gold as the
coating weight (area density) of the coating increases. As such, the ideal
conversion coating weight is not always easily attainable when the machined
surface is to be clearcoated. On fully color painted wheels and in the painted
windows of machined wheels, the suppliers can load up on the chrome since the
basecoats will cover the coloration.
SOME SOLUTIONS (PARTIAL LIST):
1. To ensure a more robust conversion coating, many manufacturers are
mandating a deoxidation stage in the washer prior to the chrome stage. This will
ensure that the conversion coating is more uniform and therefore more durable.
This results in a better substrate for the paint to adhere to at any given
coating weights because the weak areas are eliminated.
2. Powder clearcoat technologies (the most widely used clearcoat process for
wheels) are being switched from polyester to acrylic paints. The acrylics are
more resistant to environmental problems, such as peeling and filiform corrosion
(this looks like worm tracks under the painted surface).
3. Some OEM manufacturers are moving away from clear coating machined wheels
and sticking to base/clear wheels (Such as on the later ZR-1s, Indys, Grand
Sports, and Collectors) until the problems can be better addressed.
<< Does anyone have any suggestions on keeping the clearcoat like new. >>
Treat it just like on any other painted surface. I would recommend staying
away from the "wheel cleaners", as some of the ingredients of some of these
cleaners can cause corrosion problems. This information was supplied by a
leading paint manufacturer who tested all of the popular cleaning solutions. I'm
not sure which are good and which are bad, so I avoid them all. I simply slap a
coat of Liquid Glass on the wheels and keep them clean with a moist rag.
Thanks to Dan
Stauft for this information.
QUESTION: How do I know if the
odometer hasn't been changed or the ZR isn't a savage?
ANS: Odometer tampering....Hmm...This is a tough one to catch on any C4
Corvette...Tougher on the '90 and ups, but all anyone has to do with one of
those is swap a CCM out of another car with lower mileage...The only roadblock
in the way of that would be the VATS system...However, if someone is going to go
to the trouble to swap a CCM, he will likely have the capability to scan the CCM
and get its VATS code...It is then a simple matter of cutting a new key (with
the existing pattern) with the right resistance...You can look for loose dash
screws, but that won't tell you much...
The only way to really catch a "clocker" is with the documentation of the
car...Get copies of all the previous titles from the DMV.. Get the previous
registration slips, look for oil change and maintenance receipts....Find out if
it was dealer serviced, and if it was, they can run a complete computer history
of all the maintenance, with the mileages....With this information, it should be
pretty easy to catch something...Look for the obvious signs of high mileage,
such as worn pedals, ripped seats, etc..
I will say, however, that there is potentially nothing wrong with a ZR-1 that
has 200,000 miles on it....It all depends on how well they are taken care of...
Previous wrecks and salvage cars are another valid thing to check for...The
title search will show a salvage history in most cases...It is possible to buy a
car with a "clean" title that has been totaled in the past...I think its good
that you can, because if you buy such a car, assuming you know it was salvaged,
you don't want the hassles of your bank or insurance company not treating the
car with its proper value...
Many will argue that a prior salvage car shouldn't have as much value, but
personally, I disagree...Many cars get totaled and branded with salvage titles
that shouldn't be...It is so easy for a body shop to inflate the damage estimate
of a car they don't want to fix, and have it totaled, its pathetic...Whenever
there is a hurricane or other natural disaster, for example, many cars with just
paint and glass damage get totaled, simply because the body shops can't handle
the load, and the insurance companies don't want to spend thousands on a rental
car while they wait for repairs to be made...
There are also many cars that should be legitimately totaled, but don't get
reported to the insurance, and are then sold with good titles, no matter how bad
the damage...Unfortunately, cars like this sometimes have the Identification
numbers removed and transferred to a stolen car...This is HARD to catch, but
only if done properly.....If you have any doubt, look for the hidden numbers on
the frame rail, look at the engine and trans numbers...Look at the VIN plate
closely....Check the RPO label, and if you have any doubt, check the build
sheet...Documentation, Documentation, Documentation....Most car thieves won't
bother to change everything.. Unfortunately, some dealers end up with cars like
this unknowingly, and then pass them on to the consumer...
You should have nothing to fear from a PROPERLY repaired ZR-1 that has been
damaged, but you can get some leverage in the price, usually...Here are some
clues I've encountered that would indicate that a car has been wrecked or
repainted...
Look on the inner front corners of the front bumper cover where the wiring
for the headlights and parking lights run....Bad repair work always shows up in
UGLY wiring...Look for splices, or misrouted harnesses...This is a dead
giveaway...Also look at the hardware on the radiator support, hood hinges,
etc.. another thing body shops always screw up...Look for cracks in the inner
wheel surrounds...look at the shims on the upper control arms...You will notice
too many, or too few if bad framework was done....Check the tire wear...Look at
the floors for obvious dents or fiberglass repairs...Look for over spray into
the engine compartment...Look for paint on the front spoilers...Also look where
the gaps in the headlight pods would let paint through to the area
underneath...Take out the rear license plate and an inner taillight in the back
bumper...If the gas tank, or a taillight socket is the same color as the body,
its been repainted...Look under the hatch weatherstrip for paint, check the
Federal label on the door, make sure it matches the VIN...If its missing, you
may have had the door changed. Look inside the rear compartments for shattered
hatch glass...You can never get it all out...Look at the door jambs....Ugly
repair work always shows up where the quarters are bonded....Look under the car
for anything obvious...Note, some cars had the paint touched up at the plant, so
don't automatically assume that over spray means the car was wrecked...
If you don't see any of that, more than likely the car was :
A) never hurt, or
B) repaired properly....Again, talk to the previous owners, and get
DOCUMENTATION....
Take a friend along, two sets of eyes are always better than one...
That's a few of my ideas, I'm sure there are more....
Thanks to Ed Simmons for this information.
QUESTION: What if I need a brake job,
what should I look out for?
ANS: I ran across some interesting research GM-STG has done on brake
servicing, specifically brake rotors and customer complaints of brake pulsation
or "shudder" above and beyond ABS brake pedal feedback. Brake work is a huge
business adding up to about 40% of all auto service work in the U.S. Complaints
of "warped rotors", "shudder" and pedal pulsation are generating many of the
repair orders. Recent industry investigating shows that much of the work being
done to eliminate shuddering is actually making the problem worse causing
customer dissatisfaction.
Question why shops fail to adequately repair disc brakes?
-Service techs need the skills of a trained, experienced machinist to machine
disc rotors properly and many simply do not have this level of training.
-The fine finish on today's lightweight brake rotors is almost impossible to
duplicate on many shop brake lathes, no matter how skilled the operator
-Too many lathes in too many shops are poorly maintained. If the arbors are
nicked and worn, the mandrels damaged or dirty or the tool holders are not in
perfect condition, future trouble with any rotors that are machine on that piece
of equipment is a certainty.
When does rotor replacement make sense?
-In many cases machining rotors can create more problems than it solves.
-GM is considering implementation of a new warranty policy that will specify
replacement rather than refinishing of rotors that are worn unevenly, badly
scored (ie: to a depth of .060-in. or more), corroded or are below minimum
thickness.
A perfect repair or replacement of a brake rotor is completely negated if the
service tech does not use a torque wrench or impact gun with an appropriate
torque limiter attached to tighten the lug nuts when remounting the wheel. Not
using those tools invariably results in uneven torque on the lug nuts which will
*always* cause warping or lateral run out of the rotor.
The distorted rotor makes intermittent contact with the pads leading to
uneven rotor wear. The thickness variation resulting from intermittent contact
is what causes the pedal pulsation. Improper tightening of lug nuts is *the
number one* root cause of rotor warpage on all C4s. It is also an issue with
C2/3s with disc brakes, but perhaps not as critical a factor due to the thick
rotors used on those cars.
A recent survey of service techs by *Brake and Front End* magazine shows
rotors are being machine in 75% or more of the brake jobs being performed. This
means that most service techs are conditioned to always machine rotors during
brake jobs...a notion that goes back to the days of heavy disc brakes and
asbestos-based pads. Many of these service techs fail to realize that technology
is, indeed, changing and that rotors do not need to be serviced every time one
changes pads.
Many service techs routinely "rough up" the surfaces of brand-new rotors,
apparently not knowing that today's semi metallic pads need a smooth surface to
be effective. That old practice became inappropriate when the brake parts
industry stopped making asbestos-based pads that used to glaze rotors.
To add to the challenge, GM specifications in most cases limit runout to just
.003-in. on today's rotors and 65-82 rotors ought to be held to .002 in.
Precision machining of this kind also requires removal of all visible rust that
accumulates on the wheel hub flange or on the hub itself because rust flakes are
more than thick enough to cause future pulsation problems.
Any service tech or DIY who thinks the rotors they've worked on are machined
well should put them to test using a profilometer, a stylus that accurately
measures surface irregularities. Rotor faces that look smooth and ready for
reinstallation are routinely shown by profilometer testing to be very poorly
refinished and out of spec. Current rotors are final-machined during the
manufacturing process on precision grinders to ensure proper surface finish, a
finish so fine that it is almost impossible to achieve with most of the brake
lathes currently in use by the service trade.
Lots of information in circulation today has predisposed many people to rotor
refinishing rather than simply not doing any thing with the rotors at all or, if
there is a problem, just replacing them. A 1994 story in *Consumer Reports*
advises readers to "...question whether you really need new discs particularly
if the car is new and the discs have not been machined before." As a result of
this conditioning, many people will demand the rotors be refinished because they
have been taught to do that.
C4 service manuals give specific data as to conditions under which rotors
should or should not be machined and when they should be replaced. I would
advise everyone to consult that information before doing anything with rotors
during a brake job. That has always been my policy on brake work.
For example, my 1988 Chevy Beratta *never* in 100K miles and three sets of
front brake pads ever had the rotors machined. Each time, I inspected the rotors
and measured runout to find all within specs. When it came time to replace the
fourth set of pads, the rotors measured under the minimum thickness so I
replaced them, too, but I did not machine the rotors before installation. I
simply installed new rotors and new pads. My 95 Corvette is not in need of brake
service yet, but when it is ready for pads I will observe the same service
procedure.
Thanks to Hib Halverson for this info.
QUESTION: I'm having a problem with
my ZF 6-speed transmission, how do I repair this?
ANS: 1. Send transmission to ZF. They would require a deposit of about $500,
and would tear down and inspect the transmission. They would then call you and
tell you the diagnosis and an estimate of repair.
Labor rate is approx $80/hr. Repairs have run from $1500 to $4000 depending
on amount of damage and parts required.
ZF America, located in Atlanta, Georgia
Mike Patterson 847-634-3500 ext 263
2. Order a rebuilt ZF through GM STO(or could be SPO). Cost of their rebuilt
is $3300 and $1850 for the core (a deposit until they have yours back)
3. Or go to an independent contractor with ZF that sells both new and rebuilt
units - Melrose T-Tops in Illinois.
Melrose T-Tops Inc.
4310 Ellwalk
Courtland, Ill. 60112
Thanks to Dave Wheeley for above info.
Also you can contact one of the 5 regional distributors listed below:
ZR51 Performance- is a ZF 6-speed repair
shop. Bill Boudreau is very knowledgeable in the repair and care of our 6-speed
transmission. His costs are ~60% that of GM/ZF. He also offers fast turn around
in as little as 3 days. For ZR-1 Net "Gold" members Bill is offering 10% off any
parts used in the repair of your transmission. For more info contact Bill
Boudreau at (602) 740-6277 or send him an email at:
bill777@inficad.com
ZR51 Performance
5612 East Almeda Court
Cave Creek, AZ 85331
1-602-740-6277
Here's a great article on
troubleshooting your ZF transmission.
FORTE'S PERFORMANCE TRANSMISSIONS
474 Moody Street
Waltham, MA. 02453
1-781-647-1530
CONSOLIDATED TRANSMISSIONS
5606 Carder Road
Orlando, FL. 32810
1-800-578-8726
MIDWEST TRANSMISSION CENTER
40312 County 8 Blvd
Zumbrota, Minnesota 55992
1-507-824-2012
ALL TRANS PARTS
1814 N.E. Argtle Street
Portland, Oregon 97211
1-800-237-8601
Another great source for parts and ZF repairs. White Racing Products has ZF
parts as well ZF rebuilds.
For more info contact Kurt White by sending him an
email at KNJW1@aol.com
QUESTION: How do I enter diagnostic
mode for my A/C and how to get digital readout of various engines parameters and
settings?
ANS: To enter diagnostic mode, push and hold the fan up arrow and down arrow at
the same time until the LCD shows -00. You are now in diagnostic mode and may
select any parameter using the up and down arrows. To see the value for that
parameter, press the fan "auto" button.
Note: A minus sign on the display range means to add 100 to the value
displayed. So -155 actually is 255.
| Parameter Number |
Parameter Description System Faults |
Valid Values |
|
0
|
One of these will be set if your A/C controls have a LED flashing |
00 = no Faults
01 = Temp door motor circuit fault
02 = Temp door motor circuit fault
03 = Ambient Sensor Open
04 = Ambient Sensor Short
05 = In-Vehicle Temp Sensor Open
06 = In-Vehicle Temp Sensor Short
07 = Solar Load Sensor Open
08 = Solar Load Sensor Short
09 = Low Freon Detected
10 = UART Failure |
|
1
|
Temp Setting |
60F to 90F |
|
2
|
In-car Temp Sensor |
10 = Hot -130=230 =Cold |
|
3
|
Outside Temp Sensor |
10 = Hot -130=230 = Cold |
|
4
|
Sun Load Sensor |
Max Light Max Dark
L98 38
183
LT5 115 -110 = 210 |
|
5
|
Ignition Sys Voltage |
0 = 9 Volts -155 = 255= 16V |
|
6
|
Engine Speed (RPM / 25) |
|
|
7
|
Vehicle Speed |
|
|
9
|
A/C System Mode |
00 = Off
01 = Recirculation
02 = A/C
03 = Bi-level
04 = Heater
06 = Defrost
07 = Vent
10 = Manual Recirculation |
|
10
|
Blower PWM |
0 = 0 Volts 128 = 14 Volts |
|
11
|
Program Number |
00 = Cold -155 = 255 = Hot |
|
12
|
Mix Number |
-155 = 255 = Cold 00 = Cold |
|
16
|
Coolant Temperature in degrees C |
|
|
17
|
Solar Correction |
114 = Max light 128 = Max dark |
|
30
|
Stored Full Hot value |
0 to 50 |
|
31
|
Temp Door Travel Range |
100 to 200 |
|
34
|
Temp Door Position
Requested |
00 = Full Hot
-153 = 253 = Full Cold |
|
35
|
Compressor On Time |
.1 second increments |
|
36
|
Number of times below critical time |
|
|
37
|
Software version number |
|
NOTE: This was from a '91 ZR-1 document and may be different for other years.
Thanks to Marc Randolph for this info.
QUESTION: Does moving the MAT sensor
help in performance?
ANS: The idea behind relocating the MAT sensor is to delay the onset of air
temperature based spark retard. Put in simpler terms the software that controls
the spark advance has a modifier applied to it after a certain air temperature
that reduces the amount of ignition advance the engine runs.
This is done so in high ambient temps you don't run into wouldn't, what you
are doing by moving the MAT sensor is to increase the chances of running the
engine into detonation.
The favorite trick by some tuners is to also move the temperature threshold
in the software as well and increase the det sensor limits which means you are
running very close to the det borderline all the time.
If you live in an area like the southwest for instance, with this set up you
run a greater risk of engine damage, LT5's are not prone to piston damage from
detonation but do blow head gaskets due to denotation and in extreme cases
damage the cylinder head face (I can send you some nasty photos if you like!!!).
In short, lots of people do but personally I wouldn't, the problems far out
way the gains. Five years of development and testing decided that the MAT sensor
should go where it is!
Thanks to Geoff Jeal for this information.
From Graham Behan on same subject:
The control system, part of which controls the spark timing, of the LT5 is a
relatively simple thing by today's standards only 32 K as opposed to over 2mb on
some trucks. Basically there is a 8 inj table and a 16 inj table for the spark
control along with several algorithms that add or subtract spark depending on
sensor inputs. One of these sensors is the manifold air temp sensor (MAT). Since
a high inlet temperature can lead to a change in the detonation characteristics
of a given mixture we monitor the air inlet temp and modify the commended
ignition advance accordingly. Now with a relatively high compression ratio
engine, such as the LT5, the rate of applied retard for a given temperature
increase is somewhat aggressive. The sensor location in the air horn is not an
ideal place, since the surrounding heated metal can soak heat into the sensor
and give a false high reading, thereby causing a false retard condition. This
placement was largely driven by the philosophy that the LT5 should be a complete
assembly by the time it left the production facility, there are many sound
reasons that support this approach; checking system integrity and reducing
installation time at the vehicle assembly plant to name but two. Now a more
representative place to pick up the actual intake air temp is somewhere that is
relatively thermal insulated from the heat source i.e. the engine, yet is still
in the inlet air flow. So the relocation of the MAT sensor to the filter housing
is quite a valid solution since it is measuring inlet air and the high temp
protection is in place. However modifying the software to minimize the control
system response to a high air temp signal is, in my believe not such a valid
solution. Since the protection algorithm is put there for a reason, high inlet
air temps = tendency to detonate. With the advances in the modern engine
management systems engines are now calibrated closer to the detonation limit of
the fuel. Given this it is co
