First off I have a 95 GS and I am tired of this damn car. I have rebuilt the motor and when I first fired it up it runs like CRAP. The idle is horrible, it goes from 600-1400rpm. So far I have replaced 3 map sensors, the IAC motor, tps, and even the ecu. I have been told that if you unplug or replace the ecu it takes time to "learn" the motor, I just feel that it shouldn't be this bad. There are no trouble codes, it just runs like crap. It runs rough at low rpms and then at higher rpms it comes to life. I'm just completely out of ideas. I've already spent too much on this p.o.s. and I don't want to through anymore money at it unless I know its going to fix it. If ANYONE has ANY ideas PLEASE HELP. :wallbash

is all the timing right? cleaned your throttle body? any vac leaks? did you rebuilt it stock? look into buying a fcd instead of the missing link.

I'm positive the timing is correct, I checked it like 20 times, and the throttle body was cleaned to were you could eat off the thing. To be honest I have no idea what the fcd is? Vacuum leaks I have checked for and have not found any but I will look again. Thanks.

Unplugging the battery for fifteen minutes will reset the ECU... I do that everytime I add something to the motor.

Id check for vacuum leaks. Who built the motor?

I have reset the ecu mutiple times and even replaced it. I was the one who rebuilt the motor. I followed the factory service manual, following all torque specs. It's raining where i'm at right now so when it stops i'll check for vacuum leaks.

have you given the car any run time? Initial start after an ECU reset always tends to be rough, but if it doesn't clear up after a cuple of short drives, the problem lies elsewhere.

Try doing the keydance and see if the ECU has flagged a code. It doesn't always illuminate the CEL for intermittant codes, and the problem has to be flagged on multiple consecutive "trips' before the CEL will illuminate.

Have you checked the IAT and CLT sensors to verify they are within spec? both will cause issues if they have failed. (values are in the wiki)

have you verified the front O2 sensor is functional? if it's dead, it will cause these kinds of issues.

I have driven it 3-4 times without any improvement. I just didn't want to damage anything. I'm not sure if the front o2 sensor is working or not but I forgot to mention yesterday when I was driving it around my neighborhood that on my scan tool the rear o2 sensor was at 0% without any change. I know the front o2 sensor controls the fuel but the rear just tells the ecu if the cat is working or not. Also, I tried to search on wiki for the values but couldn't find them. Not sure if I was using the right wording. If you could put a link up for me that would be much appreciated. Thanks.

http://www.2gnt.com/index.php?d=CLT
http://www.2gnt.com/index.php?d=iat

Thanks for the links. I'll check those tomorrow when I get off work.

Is the idle just jumpy, or is it missing?
Check the timing 20 more times.
Check your vacumm in the intake manifold.
Check the EGR system, that stupid thing has screwed me up plenty of times.
Apply a vacumm directly to the EGR (not through the solenoid). Make sure it opens when vacumm is applied and close when it is removed.
Then pull a vacumm on it through the solenoid. Make sure it stays closed. Then apply voltage to the solenoid and make sure it opens.
Thats how I checked mine.
It gave me a 5" vacumm at idle and that threw everything off.

The rear 02 sensor decides if the catalytic converter is doing its job or not.
A missing link is a mechanical way to keep the map sensor from seeing boost. A FCD is the same thing its just an electrical way of doing it. It's more or less a voltage clamp. (These only needed if you are turbo)

Being a 95 he doesn't need an FCD/Missing link. Our ECU's can see boost and not freak out, it's just that they only see like 1/2 psi so they're not practical.

I'd do as other said, check your cam timing 20 more times, it sounds like my brother's when it skipped a tooth. Ran like dog $#!& at idle, but would run pretty well in the upper RPM. Double check all your manifold gaskets / vacuum connections, maybe do the starting fluid spray test. Not sure how far you went in the rebuild, I know some don't even pull the intake off the head if they're doin a simple bottom-end rebuild.

If you rev it up a bit (say like 2k) does it stay pretty steady or kinda cough/stumble? Is the only problem at/around idle?

Sorry about that, didn't see the 95'.

I know you said you checked a bunch of times, but is there anyway you can show a pic of the three points? The two cam gears lined up and the crank gear lined up.

It's still sounding a lot like timing.

Have you checked your coolant temp sensor? When I replaced my head it didnt want to idle and once I hooked it up it worked perfectly fine right away. It may not be working correctly.

Also check for bubbles in the coolant system, I remember somebody here always saying that bubbles in the coolant cause the car not to idle correctly, it doesn't hurt to check it out.

Hope that helps.

What is your idle vacuum?

Chances are like Mark said, your timing is off. Couple degrees will do exactly like what your describing. Some of us have been doing this longer than you have been alive, telling us what it is not is just going to make your problem last longer. Pictures of your timing will help us show you how you may be wrong.

Verify no leaks on the EGR is good advice....do it. A leak that will cause an issue this large will be a huge leak that you will hear. Its not a vacuum line. The EGR you wont hear for obvious reasons.



This isnt a complaint hotline.....refrain from posting like an upset adolescent throwing a hissy fit. It will not be tolerated.

Sorry friend came in for the weekend so car went to the side. I did however check both the intake air temp sensor and coolant temp sensor, they are both fine. I'm going to get a vacuum gauge and test for leaks on the egr. After that if its not fixed i'll break it down and recheck the timing. At that point its a definant possibility the timing is off. Thanks for the help.

Well I finally got some time to work on the car again and I checked for vacuum leaks and I checked the egr and both were fine. So I checked timing and low and behold it was a cunt hair off. So I tried to reset it following the service manual and I think I have it but it still looks like its a little off. I'm trying to get a guy I know that works for chrysler out to my house to help me out and tell me if its correct. I don't want to put it back together and find out its still off, I think that would send me over the edge. I'm just glad I figured out what the problem was. Hopefully it will be up and running by this weekend. Thanks for the ideas.

What's your location? If your close, I'll come take a look. Generally, if your timing is correct, you see it and say "Damn, that's it!" If it looks kinda off, it probably is (generally).

MB

Well I found out the problem. I was able to sit down with the tech today and the solution is so rediculously easy its not even funny. He told me to buy a cam gear locking tool. A $35 part that would have saved me over a month of headaches. He told me his first timing job on the 420a he didn't know about it either because the assholes who wrote the service manual leave it out just so you have to take the damn car to the dealership. The senior tech at his shop had to tell him about it. Its for any dual over head cam motor. I just ordered the part today. He assured me it will line up perfectly every time since he started using it, so its worth the investment in my opinion. Thanks for the offer, I really appreciate it. Hopefully by this weekend my car will be running correctly.