rough idle

[gsf1200s]

1993 J30

Driving the car this morning everything was running fine, stopped for coffee and run some errands maybe 30 minutes. When i started the car again the idle was a little low and really rough. it smoothed out some with acceleration, but would come right back when i stopped. the idle speed never dropped too low or stalled just rough running. mostly smooth at hwy speed but would roughen up at random times. didn't seem to be low on power

any ideas??

[J30tVance]

Same happens to mine. Runs like a champ when it's cold, still a little low idle. But when it warms up it runs really rough and idles to almost stalling. I have been told to clean the throttle bodies by someone. I have yet to do that though

[fourdrinie]

I would invest in a new MAF...

[GerryO]

I'd be checkin' for something that is a bigger issue after the engine is warmed up, like a vacuum leak, or something that is more noticeable at idle, like a faulty injector. Time to pull some codes or replace a spark plug?

[gsf1200s]

A little more info, the idle issue is the same warm or cold. I cleaned the MAF a couple of months ago when it was having a different issue. The TPS and Idle Air Control are both new within the last year. idle seems like there it is running a cylinder low, but now loss of power seems strange.

[gsf1200s]

Also, it was a little rough at speed this morning, but not as consistantly bad as it was at idle.

[yodawill2000]

May be a injector on the way out.
Have you ohm'd them out yet ?

[gsf1200s]

haven't had a chance to check anything yet. try to get some direction before doing anything or spending any money. was going to try pulling the coil pack leads to see if it is a dead cylinder.

[gsf1200s]

also, no check engine light

[yodawill2000]

When my injectors went bad it did light the CEL.
And it was way obvious it was running on 5 cylinders.
Shook like crazy.

[gsf1200s]

pulled the leads from the coil packs last night and narrowed it down to the middle cyl on the pass side. i may have to take it in to get the work done due to time issues. if i do would i be better of having all the injectors replaced since most of the cost will be in labor?

[GerryO]

There are a few codes that don't cause the CEL to turn ON, but failing injector coil isn't one of them, though things can be marginal/intermittent for a while. Ohm checking is simple and conclusive.

Coilpacks are pretty reliable and easy to swap around. Maybe a bad or fouled spark plug? Not many people pull the plenum to replace injectors and if one is bad, how about the others (ohm check) if corrosion/age is part of the problem and who knows about reconditioned injector reliability?