So I have been trying to pin down my eratic idle. Mostly at start up, jumps up and down about 700rpms. I thought it might be an O2 sensor so I unplugged the 1st one (before the cat--i have 2)-and no change whatsoever, so I take it the sensor is okay? The CEL came on which I expected. I have cleaned the throttle body so its not that, ran seafoam. I am down to 2 more ideas. Perhaps the throttle positioning sensor, or the idle air sensor. With the TPS, what would be the trouble symptoms? The idle doesnt drop below 800rpm, just fluctuates like I am tapping the gas-up and down, and it does it more noticabley when the engine is cold. Can I clean the TPS, or does it need replacement. The write-up I found here just suggests reajustment.

 

Do you have a FSM and a multi-meter?

 

Hey. Turns out we've got siblings.

Just today I noticed the same exact wierd idling and its the first time it really bothered me, well, it goes away when she warms up usually. I've never driven cold weather, or driven this car during any real difference in weather like this... so its all new to me.

 

nope...mechanically I'll try anything and figure it out, electronically I might as well be in kindergarten...

 

I would suggest looking at the AIV valve or a vsv. The TPS could be the culprit as well, but your going to need a multimeter to figure it out. My bad idle was cause by the air valve in the throttle body being filled with oil from a bad PCV valve. The gasket inside gets oil soake dand in my case dissolved and was torn from the inside. Just a thought

 

I have a brand new pcv valve but what is this air valve thingy?

 

Adjusting the tps isn't to hard at all. All you do is test resisitance at 2 different throttle postions and you can find out if that is your issue. I dont have the exact link to the tps adjustment page but its somewhere on 4crawler.com. Someone will chime in with the address.

 

This same question was asked over on 4x4wire today. Here is the direct link to the TPS adjustment
roger brown

 

Shoulda asked sooner, What year/engine/trans do you have?