i need help!!!

[nicerydez]

i have a cavalier and i just replaced the engine with a new re-built one and ever since then i've had idle issues. all it does when i leave the car to idle it'll rev a little and then sit at about 1000 rpms then it'll start to stall, then it'll rev then start to stall etc, etc. i'm getting a little pissed cuz no-one can figure it out. i've taken it to 6 different shops and they all say they dont know whats up?? i've replaced my fuel pressure regulator, my EGR valve and cleaned my intake out?? can anyone help me???

thanks alot...

[Pikachoo]

Sounds like a vacuum problem. The only way to be sure is to check all your vacuum hoses under the hood to make sure that they are securely fastened. Don't forget the hoses that go from the throttle body down under the intake plenum. If when you did the swap you used the old hoses, sometimes they crack, so make sure that's not the case either.

You might also check the gasket behind the EGR where it mates to the plenum. If it's messed up or missing (it's happened), you'll have a wild idle.

When you figure it out be sure to tell us!!

:sun: :sun:

[nicerydez]

yeah the gasket is fine cuz i replaced all of them when i did the engine. i was told that it could be the idle air control valve and do you think that it could be the problem? it just all the vacume lines are kinda hard to access i guess if it needs it i should do it eh' hehehehehehe well thanks.

later.....

[nicerydez]

sorry, just another note, when i un-plug any other sensor, like my MAP sensor for instance, my engine will idle perfectly but with the exception of it stalling when i stop. thanks again


later....

[mdb25]

Well, if you aren't getting any check engine lights, then I'm going to guess that your sensors are ok. It might be a good idea to try a new computer (PCU or ECM). They're fairly cheap (about 60 bucks) and they should be replaced after several years, just for preventative maintenance measures. You have to be certain to match the exact computer with your engine.... ie dont use a z24 computer for a regular 4 cyl cavalier. I've seen computers go on Z24's before and it baffles mechanics. Good luck dude.

[nicerydez]

well i got a new computer for my car but the guy told me after i bought it, that it was from an auto but my cav is a 5-speed. He never asked me, he just assumed that it was an auto for some reason, I couldn't return it or exchange it because it was an electrical item! the guy was a real jerk about it so now i'm stuck with an computer from an auto, what do you think should i give it a shot, or just go buy a new one for a 5- speed tranny?.... if i do give it a shot, is there any way that i could make sure the connections are all right before i connect and start the car?? what i mean is, is there any way that there is a difference and i'll screw someting up??

thanks alot..

[Shortbus]

The control module for a auto and manual are the same. The difference is in the removable EPROM which is the predetermined information the car runs on until open loop is activated.

There is a difference between 6cyl and 4cyl ECM's though.

Does the car act up when hot or cold?

[nicerydez]

the car will idle really good when it is cold outside. why do you ask? well that computer #'s didn't match exactly so i'm going to pass on the install. i'm getting kinda frustrated because i try alot of shops and when they do a diagnosis the computer says that my computer in my car is acting up. it only does this occasionally, so what one shop did was replace the computer with another one and they left it for a while but the same thing happened. the computer said that my computer in my car was acting funny. man i hope this problem can be fixed, it's embarassing sitting at a set of lights with a sweet ride but it sounds like shit.


thanks alot...

[Shortbus]

I asked because when the car is cold the engine runs off of the information in the prom, this is closed loop operation, and when the car warms up it starts using the information taken from all of the sensors. I will run your problems by some of my techs and see if I can get some more ideas about this. will get back to you.

[nicerydez]

cool, thanks! i appreciate you checking this stuff out....


thanks alot....

[96Cavalier]

I had the same problem with my 96. I started replacing my sensors from the cheapest one first...When i replaced my TPS(throtle positions sensor)it still persisted for bout a week then quit.

[nicerydez]

so then i should replace my TPS? sounds good!


thanks alot.....

[nicerydez]

i have another question, would the fuel pressure regulator be the cause of all this greif? somebody told me this so i was just wondering? i bought a brand new one when i replaced my engine, and well like i stated earlyier, once i put the new engine in, it been really rough!

thanks......

[96Cavalier]

Replacing the TPS couldnt hurt....and is inexpensive ....Think it runs around $12.00 and is rather simple to replace

[nicerydez]

yeah i replaced the TPS but nothing happened, but i'll wait a week or so to see if anything changes? my main concerne is the FPR ( fuel pressure regulator) if this could cause the problem? when i remove the vaccuum line from it the engine kinda idles a little smoother, but still lopes in it's idle! i thought that by removing the vaccuum line it would cause the car to stall or something? so i was wondering if the FPR could be the problem by lacking fuel to the engine at times???