99 grand am running rough

my wifes was driving the 99 grand am 4 cyl. she said all of a sudden the trac off ligh and ses came on the car ran very rouch acts like it doesn't want to shift until you let off the gas petal then it will shift. I replaced the trans filter and this did not help. can anyone tell me what the problem might be?

I replaced cam shaft position sensor as I was getting code 342. I'm also getting code 300 random missfire I have changed the plugs, plug boots, coils, fuel filter reset codes and still getting random missfire code 300

I do not get code 342 since I changed the cps. getting code 300 only I have cleared the codes 2 times using a scanner.

so I was frustrated and just wanted the car fixed I took it to the repair shop I have AAA so I picked a shop from there web site and had AAA tow my car to the shop.so they looked at the car and called me and said it was the plugs and the boots I told them for the third time I had already changed plugs and boots I asked are you sure this will fix the problem they told me yes they also told me that the new plugs I put in on saturday were fouled and had to be replaced on monday. and yes I was hot when they called and said the problem was not fixed so on 12/11/06 they called and said the computer was bad that the computer was constantly grounding 1 & 2 I will grill them and get a garuntee in writing that this will fix the problem or I don't pay. computer 649.00 to flash computer 109.00 install computer 42.00 I plan on contacting AAA about this AAA aporved shop. I may just take it to a GM dealer if they can diagnose the problem and fix I'm don't think the computer is bad I could be wrong. I'm posting this hoping that it may help someone in the future I will post the fix when I or someone figures it out. I suspect the injectors or the injector wiring.

well the repair shop ripped me off the shop replaced the computer and it fixed the problem the installed a remanufactured computer for 650.00 the delaer sells it for 517.00 new napa sells a remanufactured computer for 119.00 I have complaints filed with attorney general the bbb the ftc and AAA and Good year as the shop was a good year repair shop. hpefully I can get some money back..


Thank you in advance

Traction control on these cars is like ABS in reverse as far as programming. You may have a wheel sensor problem. First, check each wheel visually to make sure you havent run over anything that could have interupted the signal from the reluctor ring, like a plastic bag or something. Ultimately, you'll have to have the vehicle scanned. The most common problems wiring or sensor related. The sensors on this car are part of the wheel bearings, so they are costly to replace.

costly to the tune of 350U$ by the dealer, dont ask me how I know this....

costly to the tune of 350U$ by the dealer, dont ask me how I know this....
thats probably only one wheel too... it's sick really. I'm not even a big fan of ABS or Traction Control. Honestly more than one person has agreed that these options are really meant to make cars look safer... and in part are for people who don't know how to drive in conditions that call for these features.

wheel speed sensors are a problem on grand ams.
When replacing them dont buy cheap chinese hub/bearings.
The brand I usually use starts with a "T" .... about 110$(us) at autozone/advance auto.

Another thing , dont us an impact wrench on your new one's :nono:
or they'll fail quickly.

Alot of shop do this and dont even know that its bad for the electronics inside.

wheel speed sensors are a problem on grand ams.
When replacing them dont buy cheap chinese hub/bearings.
The brand I usually use starts with a "T" .... about 110$(us) at autozone/advance auto.

Another thing , dont us an impact wrench on your new one's :nono:
or they'll fail quickly.

Alot of shop do this and dont even know that its bad for the electronics inside.

xeroinfinity, perhaps you could provide some insight between the failure of this system and driveability problems that occur. My understanding of this sytem is basic so far...

Well the issue with the wheel hub sensors are that the contacts inside the sensor gets worn out. Or the wires get broken/fraied, or the bearings them selves start to fail causing a roaring sound.

The traction control, when working correctly, keeps the tires from spinning by regulating throttle & trans line pressure to keep it from spinning the wheels.

When this fails, your traction controls obviously doesnt work.
Also the ABS is disabled when the trac control is off or not working.
ABS Works best at speeds above 30mph.

Now why do they fail.....
Well several reason could be a factor.
IMO its the design of the cars suspension, camber.
But also can be from cheap/defective parts, bad install(using impact wrenches), or just bad driving habits.

Ian Szgatti, as you stated before the car should be scanned before you go and buy parts.

Also the part name is TIMKEN .

Well the issue with the wheel hub sensors are that the contacts inside the sensor gets worn out. Or the wires get broken/fraied, or the bearings them selves start to fail causing a roaring sound.

The traction control, when working correctly, keeps the tires from spinning by regulating throttle & trans line pressure to keep it from spinning the wheels.

When this fails, your traction controls obviously doesnt work.
Also the ABS is disabled when the trac control is off or not working.
ABS Works best at speeds above 30mph.

Now why do they fail.....
Well several reason could be a factor.
IMO its the design of the cars suspension, camber.
But also can be from cheap/defective parts, bad install(using impact wrenches), or just bad driving habits.

Ian Szgatti, as you stated before the car should be scanned before you go and buy parts.

Also the part name is TIMKEN .

Thanks for that info xeroinfinity, but I am more interested in the anomoly of "running rough" as a result of the TC malfunction, as opposed to a general description of system operation. That part I am familiar with.
Given the refresher though, I assume that the rough running would be due to the throttle and trans line pressures modulating? thanks in advance

Thanks for that info xeroinfinity, but I am more interested in the anomoly of "running rough" as a result of the TC malfunction, as opposed to a general description of system operation. That part I am familiar with.
Given the refresher though, I assume that the rough running would be due to the throttle and trans line pressures modulating? thanks in advance

Well the SES light was on so it could be several things causing the rough running.
So this may not even be related to the ABS or wheel hub sensors.
But when the traction control is working it does or can cause the engine to appear its running rough, when its actualy just normal trying to keep the tires from slipping.

Thats why I said "get it scanned first !!!" :grinyes:

I replaced cam shaft position sensor as I was getting code 342. I'm also getting code 300 random missfire I have changed the plugs, plug boots, coils, fuel filter reset codes and still getting random missfire code 300

Thank you

I replaced cam shaft position sensor as I was getting code 342. I'm also getting code 300 random missfire I have changed the plugs, plug boots, coils, fuel filter reset codes and still getting random missfire code 300

Thank you

Did you feel the misfires as a result of your CPS? code 300 of course seem to be in direct relation to the 342. 342 is a low CPS input code.

One thing I might suggest is performing the computer re-learn procedure. I don't know it off hand for your car, but it's worth trying. Figure out that procedure and unplug the fuse to the PCM/IGN for a few minutes. The do the procedure. If you replaced the CPS then the problem could be in the wiring to the CPS.. I'll know more later, unless somebody else here does

I replaced cam shaft position sensor as I was getting code 342. I'm also getting code 300 random missfire I have changed the plugs, plug boots, coils, fuel filter reset codes and still getting random missfire code 300

Thank you


IS their still a code showing for the cam sensor ??

You do neeed to do a Camshaft relearn procedure.
I know if the Crank sensor is changed,
and thiers a code being thrown you have to do the relearn, but usually someone with a scann tool capable of doing it or the stealership ... :shakehead

I'd try the Passlock relearn procedure, but you just might have to call and find a shop(dealer or ) that can do the relearn if this doesnt work.

Attempt to start the car ,
leave it in the on position for 10min.
Turn it off for 1 min.
Repeat 3 times.

Your random misfires can also be your injectors being clogged/dirty and or the wires have a short in them.
Try some good injector cleaner.

You may also replace the coil housing - the white plastic case for the coils - it's $15-20 at most parts stores. I replaced the coils, plugs, plug boots, and still had the misfire. I had the ignition module checked and it to was good. The guy at the store asked if I had replaced the housing and sold me one. Fixed the problem. I bought it at O'Reillys Auto Parts.

This will probably fix the misfire problem.

Hi did you check throtille position sensor? check connectors at the pcm make sure they are pluged in tight. Pcm is under the glove box, so go under the dashboard open plastic cover you will se two plastic screws that you can turn with your fingers, and there you will see two pcm connectors you will need 8mm socket and be very delicate with those. good luck Aki

Hi did you check throtille position sensor? check connectors at the pcm make sure they are pluged in tight. Pcm is under the glove box, so go under the dashboard open plastic cover you will se two plastic screws that you can turn with your fingers, and there you will see two pcm connectors you will need 8mm socket and be very delicate with those. good luck Aki

I dont know what your experiance is with 99' GAs,
but the PCM is not on the pass. side.
And I wouldnt mess with the PCM unless its absolutly nessesary.

Your 97' GA is way different then the 99+.

The TPS on these are pretty good, not many go bad either.

just to comment on coil packs that start with "D" - I was not very impressed (vorse than my old ones :) my suggestion measure your secondary and primary resistance for all coils that you have compare them to specs or go to store that has coil packs that start with original "D" measure them and compare. in short buy original (my new coil non original one was worse by 3000 ohms for the secondary resistance). good luck.

I hate to send this into nomans land, but what is the possibility that this is a timing type of issue... a four cylinder? Does this motor have a timing chain or a timing belt??? I really cant wait to hear the outcome of this one.

Hey Ian,
It is possible but not likly.

I've seen 99's (4cyl) w/175k miles and no sign of damage to the gears or chain. :dunno:

I still think its fuel related not fire .....

Hey Ian,
It is possible but not likly.

I've seen 99's (4cyl) w/175k miles and no sign of damage to the gears or chain. :dunno:

I still think its fuel related not fire .....

whoa... I think we've been missing the boat here. I had to read the original post again to re-think this from your position... and the edited original says the problem was fixed by a remanufactured PCM. The problem was in the fuel managment system though, so you were accurate i guess. Ok, well this thread is now dead.

:uhoh:
I hadnt even read his 12/26 update/edit part.....
This has happend to many 99+ GA owners(stumped me too a few times) and the shops just run you round and round till youre broke :shakehead

OK BREAKING NEWS HERE FINALY!!! sorry Xeroinfinity for this caps I had to use them this time :) because people need to see this one it will probably help them solve the similar problem that I had. Notice this time I said problem that I had :) it is out now :) :). This 0300 code that I was chasing for a long time I mean printing all kinds of electircal diagrams, asking my ASE instructors, reading all kinds of books to solve my problem and not to mention all the unecessary parts that I changed when I was younger and unexperienced (now I see that all those sometimes expensive parts vere good ;( . But first I have to thank you Xeroinfinity for showing me the right direction at least - remember when I said "you are very close I think" (low pressure for opposite injectors #3 adn #4 on V6 3.1. YES I did what I told you I was planning to do. Here it is finally:
reminder GA was shaking (misfiring only in P and N) and mostly on #3 cyl sometimes on #4
solution:
1. engine on and in Park
2. used otc scanner to monitor all cilinders
3. noticed that #3 was misfiring
4. pinched outlet rubber fuel line after the fuel pressure regulator
5. noticed BIG difference in idle this time and all cylinders showed "0" for misfiring. In conclusion specs say: fuel pressure is ok if between:41-47psi looks like it was not enough for my GA 3.1 or the fuel pump filter bag is very dirty. So who ever has this problem try this before changing your O2 sensors, cleaning throtile bodies, cleaning injectors, fuel filters pcv valves, coil packs, spark plug wires etc........ Thanks onece again. And Happy New Year from Aki