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Pontiac Grand Prix
Repair Questions and Answers
Question:
1992 Pontiac Grand Prix
mileage: 80,000. I purchased this car about 4 months ago.
Ever since I bought it, it has had this problem: after
starting the car, it revs at about 1800 rpms for about
ten seconds, then jumps to anywhere between 2500 and the
rev limiter at 3000 rpms. It stays there until the
engine is completely warmed up, and since I am in
Daytona Beach, it is about seven to ten full minutes.
Also, when it first jumps up, the check engine soon
light comes on. Seeing this, I took the car to a trusted
mechanic to read the codes for me. It showed an 89.909
or 85.909 (hard to read his writing here) IAC. Seeing
this, he replaced the idle air control. I paid the bill,
took it home. Next day, same problem. It only happens
first thing in the morning and at about four hour
intervals thereafter; has to be cold. I took it back the
next weekend. He said the battery was only reading 11.45
V and should be replaced. I will soon. He also said that
it could be the air conditioning pressure valve, sensor,
or something, as this was in the same circuit as the
idle air control. By the way, the code still reads bad
IAC. He also said that a sensor in the air cleaner box
was reading 40 degrees below zero. (I thought THAT might
have some effect on a cold start) but he said after he
cleaned the contacts, all read properly. 42 dollars
later...the next morning, same thing! I am getting
frustrated here, as I know that this cant be good for
this motor. I am considering going to the dealer for
this, but I have had no dealings with them and am
skeptical about their efficiency and honesty. Can you
give me any advice? I am somewhat mechanically inclined
and have a rudimentary set of tools. I am reluctant to
mess with an exotic modern motor such as this one
though. Please forgive my long explanation, but I am
hoping that the more info you get the easier the
diagnosis. Also, if this helps, I have an oil leak
coming from about half way up the block. The whole
bottom of the engine is soaked. It seems to have gotten
worse after a recent 400-mile trip. Maybe the problems
are related. Any advice would be appreciated.
Answer: The "check engine" light will "light"
when there is a malfunction in the engine management
system. The fault code is then stored in the computer.
The computer must be scanned with a
pocket scanner to retrieve these stored faults to
pinpoint the malfunctioning component.
Question: 1998 Pontiac Grand Prix
mileage: 124,000. I have a 1998 Pontiac Grand Prix with a
3.1. It has the heavy duty cooling system (2 fans). The
AC hasn't worked in a long time and I recently
discovered that the cooling fans are not working either.
I don't know how long ago they stopped working. When I
put the car in diagnostic mode, both fans come on fine.
Looking at my Haynes manual (severely lacking in
electrical logic) it appears that the computer grounds
the coil on the relays to activate the fans and A/C
compressor. I opened up one relay and clipped a test
wire on the computer side of the coil. As soon as I
grounded it, the AC compressor came on. I moved that
relay into the other sockets for each fan and I could
turn those on as well. As best I can tell, the computer
isn't getting something it needs to turn them on. I
don't feel the computer is messed up since it will turn
them on when in diagnostic mode. There are no codes on
the computer. The temp gauge works fine. I just flushed
the coolant and the low coolant sensor appears to work
as well. What should I look for next and what would be
the test procedure? This is not my daily driver but will
be once Firebird hibernates for the winter.
Answer: It sounds like you have a
bad temperature switch or a bad temperature gauge. It is
located on the lower right rear of the engine. Don't
confuse it with the temperature sensor for the computer
which is located on the top rear right of the engine.
Follow-up: Took the car in last
night to get the cooling fans fixed and replace the
stolen lights. The dealer just called, here is the deal:
The fans work fine and come on at 228 degrees.... but
the gauge on the cluster reads 260 (basically pegged) at
that point. The problem is the gauge is hosed and it is
$200 to whatever to get it fixed, or many much more to
get it replaced. They changed me $30 bucks to give me
that information. Not too bad... but who would have
thought it was just a messed up gauge the whole time. I
will most likely install an aftermarket gauge. Thanks
for all the help.
Question:
2000 Pontiac Gran Prix mileage: 100,000.
Severe engine leak is probably from the distributor
housing. I have been told that the plenum, intake
manifold and one head must be removed to extract the
shaft and replace an O-ring which is the cause of the
leak. Rather than taking the shaft out, why
couldn't you seal the top with silicone for example and
reduce the overall effort? Is there any downside,
since the internal o-ring would still leak?
Answer:
We do not think that sealing the top with silicone
gasket would work. We have been able to replace
the “O” ring seal by removing the throttle bore for
access to the distributor.
Question:
1999 Pontiac Gran Prix mileage: 122,000. I
have a '99 that is giving me fits, specifically
with the transmission. The car progresses 1-3 gear
acceptably. When the ambient temperature is above
40-45F, the car will not shift into 4th gear.
Below that temperature 4th will engage appropriately.
When driving down a hill in third such that the car is
being held back just a bit, you can shift to 4th, the
car feels as though 4th engages, but when you begin to
accelerate, its obvious the car is still in 3rd gear.
Given that the car operates in 4th in cold temperatures,
I figure the problem is not mechanical, that it is
likely sensor related. I have had the car
connected to a computer twice, no codes are stored.
Any suggestions?
Answer: Your transmission may be ready
for service. Replacing the filter and fluid may
correct the problem. If not the valve body will
have to be removed and cleaned paying special attention
to the TCC solenoid. The TCC solenoid may have to
be replaced.
Question:
1995 Pontiac Grand Prix mileage: 51,000.
I got stuck in a traffic jam a couple of days ago and my
car did something it never has done before, it felt like
it was going to stall. The rpm's kept going up and
down. Then the next day while driving normal I had
another problem, I think is related. When I drive
at a steady speed, say 50 mph, the engine has a constant
vibrating that makes the car shake. The only
way to stop the car from shaking is to step on the gas
to increase the speed. Also something I just
noticed during this time was that my exhaust makes a
putt-putt sound while the car is in park and running.
Are these 3 separate problems or interrelated? Any
help on this matter I would appreciate. Could a
tune-up possibly remedy any of this?
Answer:
Your car may be ready for a major tune-up including
spark plugs, plug wires, distributor cap, rotor, fuel
filter and air filter. Also, perform a fuel pump
pressure test and a compression check. Clean
fuel injection system including throttle bore, idle
speed control motor and passages. If problem still
exists, scan computer for trouble codes.
Question:
1995 Pontiac Grand Prix mileage: 74,500.
My engine is leaking oil. There is no puddle of oil
under my car; therefore, it must be burning up
somewhere. I have had the gaskets in the
distributor shaft replaced by a reputable mechanic who
thought that was the problem. But, I have only
driven 1200 miles and have had to put 2 more quarts in
already. In 2500 miles, I've had to add 4 quarts
of oil. Is my engine bad? Should I ditch the
car?
Answer:
You are probably having internal engine problems.
We are guessing broken piston rings.
Question:
1995 Pontiac Grand Prix Mileage: 40,000.
Bob and Ken: Just recently, I started noticing a
noise emanating from the steering column every time I
turn the wheel. It sounds as if it is coming from
the area where the steering wheel connects to the
steering column. The noise reminds me of a
clicking egg timer, only the frequency of the "clicks"
is determined by how quickly or slowly the wheel is
turned. Also, the noise remains constant
regardless of the temperature or how long the car has
been driven. I am hoping you may have an idea as
to what may be the cause of this problem and how I can
go about taking care of it. Thanks for your time
and your advice.
Answer:
Your noise is most likely coming from either the turn
signal switch or the steering wheel lock pin.
Question:
1990 Pontiac Grand Prix mileage: 131,000. Had
transmission serviced (fluid replaced) by our regular
mechanic. After servicing it drove very rough when
the automatic transmission would down shift - it made
you pitch forward/lurching as you slowed. Returned
to mechanic, he checked it over and stated that the only
thing to do was to disengage the torque converter?
This performs the shifting for an automatic
transmission. Any other suggestions?
Answer:
Your car has a lock-up torque converter in the
transmission. It locks-up only in high gear.
It is supposed to disengage at lower speeds. Yours
is not disengaging. There is probably a valve in
the transmission “hanging up”. The torque
converter is controlled by the TCC (Tongue converter
clutch) solenoid. Replacing it should fix your
problems.
Question:
1998 Pontiac Grand Prix mileage: 74,000. If
the oil filter falls off and I lose all my oil while
driving, does the oil pump burn automatically or is
there anything to save it? Is there anything
connected to the gas pump on my car that would turn my
engine off to save my oil pump? How much does is
cost to change the oil pump on my car and how long?
Answer: If the oil filter falls off, the
entire engine may be ruined. Nothing automatically
shuts off the engine.
Question:
1993: Pontiac Grand Prix mileage: 79,000. My
car is having problems idling, it won', It stalls.
The service engine soon light comes on. I got the
diagnostic code off the car, it flashed code 33. I
was wondering if you could give me a hint on what could
be wrong.
Answer:
Code 33 is a map sensor problem. Check the engine
for vacuum leaks. Check the exhaust for blockage
(catalytic converter). The map sensor may be
faulty.
Question:
2001 Pontiac Grand Prix mileage: 105,000. Hi, I
have the above car. I just purchased it from a
close friend who says he never had any problems with it.
After I drive the car around for a while, it won’t start
after I turn the engine off. After an hour or so, it
will start with no problem. The engine does crank
and all lights and electrical work, but it just wont
turn over. Whenever I take it to a mechanic, the
car does fine! I’m very frustrated and tired of
getting stuck. When I try to start it' it almost for a
split second tries to turn over then it just cranks.
I think the computer is telling the car not to start for
some reason. The car has 25,000 miles on a rebuilt
transmission and engine.
Answer:
Intermittent problems are very hard to diagnose.
Your no start problem may be your fuel pump. Try
to check it for pressure during the not start problem.
Also, check for spark at the spark plugs.
Question: 1990 Pontiac Grand Prix
mileage: 98,000. How difficult is it to replace a bad
coil and a ignition module. I can do a lot of repairs
myself but the shop I took it too wants almost five
hundred dollars. The coil cost $20.00 each and there are
three of them I think but only one is bad, and the
ignition module is about $68.00 per Auto Zone.
Considering that they will mark the parts up still the
rate of labor seems that this is a job that could take
several hours. Is this task easier then what the labor
cost make out to be?
Answer: The job takes one to two hours to
replace the coils and the module.
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Prix-1 / Grand
Prix-2
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