05 pt cruiser rough idle


#1

I have an 05 pt cruiser that idles rough sporatically. Sometimes it idles smooth, sometimes it is rough but will calmndown when i shift into gear, and sometimes it is rough when i let off the gas and come to a stop sign. When i first crank the car, the idle is rough and will act like it wants to cut out when i first back out of the drive way, but it clears up and drives better after getting gas. I have changed the plugs and wires, which did help, but there is something else still causing some problems. When at cruising speed, you cant detect any stutters or other problems. I looke at the vacuum lines and have a bottle of injector cleaner on 3 tanks of gas back to back with no apparent change. What am i missing? I did put a PCM on it a few years back, is it possible it has gone bad? The gas milage also has seem to be suffering. I also checked the air filter as a possible problem, but it is very clean.


#2

@redneckredz

Is/was the check engine light on . . . ?!

If so, what fault codes do/did you have?

After telling us what codes you have, I would thoroughly clean the throttle body and the idle air control valve

By the way, why did you replace the PCM . . . ?


#3

No engine codes at all. I changed it a few years back because it had over 150000 miles and figured it was due.


#4

If the maf is dirty it will cause rough idle. Also, dirty iac and intake will cause it.


#5

If it idles poorly but runs ok at higher speeds, a vacuum leak can cause that. You get a too-lean mixture at low speeds, but at higher speeds, going uphill, etc, the vacuum leak is such a small percent of the total amount of air being drawn into the engine, the symptom disappears.

Suggest a complete vacuum system check-up. This includes looking for loose or broken fittings, and checking all the vacuum operated components for internal diaphragm leaks.


#6

Well, after getting the car out of the body shop after hitting a deer, the idle problem has strangely enough left as mysteriously as it started.


#7

No engine codes at all. I changed it a few years back because it had over 150000 miles and figured it was due. …That is the strangest thing I ever heard.