Surging Idle when cold.

[martina]

Hello all. Lately have been noticing a surging idle when i start up from cold. This is not a rough idle, rather an uneven one. Rpm's waiver a couple hundred. Say 800-1000 back and forth. Once truck is driven short time, idle is a smoooooth 600 or so. Any ideas? Recently done plugs, fuel filter, pcv valve, cleaned maf. Have reset computer a couple times. The surging is also slightly evident when driving the first couple of miles until things warm up. After that all is fine. What else can I check? Any help greatly appreciated.

Thanks, Al

 

[rednose]

Did you get the surging fixed, mine has done this for a while now and I have had no luck in fixing it, even if I hold steady throttle at about 2800 rpm it will still go up and down till it runs for a few minutes.

 

[TPLYNCH]

Have you cleaned or replaced your Idle Air Control valve?

 

[Ross-N-Chicago]

TPS Sensor?

I replaced my Throttle Position Sensor, replaced gasket and cleaned the Air Bypass Valve (Idle Air Control on 95s & up I think) and now no probs, smooth idle. Are your plug wires good?

 

[rockymntnhi]

I had the same prob. awhile back . Changed plugs/wires etc. All it ended up being was an Xtemely dirty air filter . Cleaned it and the prob has been gone since . Goodluck .

 

[BigVicXLT]

Hmmmm....

I replaced my Throttle Position Sensor, replaced gasket and cleaned the Air Bypass Valve

...where are these items on a 92 XLT?...mine has just started doing the same thing...plugs, wires, PCV, air filter have all been done....thanks!!

 

[red96camaro]

I would say it's your IAC(Idle Air Control)
There are MANY problems with the IAC in the SOHC 4.0 engines. If that is the engine you have I would say that is it. It went on me $90 part

 

[Ross-N-Chicago]

the TPS on a 92 is the black sensor that sits on the top right of the throttle body. I believe its about $25. The Idle Air Control Valve is on the right side middle of the upper intake manifold (about an 8" long cylinder). Disconnect the elec. relay, take it off and spray the heck out of it with brake cleaner and use a toothbrush or q tip to help out; replace the gasket and reinstall. I didn't see if your replaced plug wires, that could help too.

 

[BigVicXLT]

Thanks, I''ll try that...seem to start when in got cold outside...probably a coincidence...wires have been replaced...happy holidays