Rough Idle

[M.R.]

Hi Folks,
My 92 runs smooth on a cold start , But after it warms up when sitting at a light or stop sign I am getting a rough idle with code showing. any ideas on where to start first ? I am thinking maybe plugs/wires or maybe an o2 sensor any idea's ?

Thanks
M.R.

 

[John Robinson]

What Codes

If you are getting codes what are they. With the codes we can tell you what the system says is not functioning correctly. That is better than throwing parts and money at the problem.:cool

 

[LT4man]

You can take your Vette to Autozone or one of the other parts mass merchandisers. They can hook their scan tool up to your Vette and tell you what codes are set.

You can also obtain the codes yourself. If you do an internet search for GM trouble codes you can very easily find the procedure.

SAVE THE WAVE!

 

[LT4man]

Go to this site: http://sethirdgen.org/dtc.htm

SAVE THE WAVE!

 

[M.R.]

If you are getting codes what are they. With the codes we can tell you what the system says is not functioning correctly. That is better than throwing parts and money at the problem.:cool

I am sorry, What I ment to say was I am not getting any codes.

 

[pns0ccc]

I had the exact same problem last month. I found the wire on #7 Spark plug had worked its way almost off creating flashover. While the plug wire was not completely off, it created incomplete firing. Good Luck

 

[G Winter]

You said it ran smooth cold but rough warmed up. I had that with my L98 last summer. turned out I had two bad injectors, instead of 16 ohms I had 7 and 9 on two of them. replaced those and it ran smooth. A weak injector will run smoother when cold cause the ECM is calling for more pulses to richen mixture when cold,so the weak injector will supply enough fuel to keep it from missfiring.

Glenn

 

[SSTibet]

Had the exact same problem. Changed the O2 sensors and the problem went away.

Cheers,

Selim

 

[WhalePirot]

closed loop

Could be many things, as the car is entering closed loop, i.e. using input from the sensors, any of which could be failing. Check the simple things first, like connections of all wires and hoses; check vacuum readings, and the like. Problems with the basic items can confuse the ECM which is most likely to show up at idle or under load.

Other clues, such as higher mileage O2 sensor (likely needs change between 30-50k miles) can help you narrow down where to start.

Are you saying that the car seems normal under acceleration; the only issue is at idle?

 

[M.R.]

Sorry, I've beenout of town for a couple of week's and away from any computer to get back with you on this problem. I put new plugs and wires,cleaned the throttle body,PCV valve and fuel filter and seem's to run great now. Don't know which one it was, But the problem is solved and is running good now.

Thanks
M.R.