intermitant idle surge

[daveanton]

maybe you guys could help me out with this one.. we have a 98 explorer eb..4.0 sohc. just recently started having idle surge problems.. park, drive,nuetral, doesn't matter what gear you are in it will suddenly surge to about 2500 rpms. sometimes it will return to normal quicky sometimes will take a while to come back down. there is no rhyme or reason why it does this it is intermitant.

Replaced the IAC thought it was fixed but has done it again since. no check engine light at all. any thgoughts would be great

 

[97greenmonster]

I would clean/replace it again, and aslo clean your MAF sensor with MAF cleaner. Its one of the two, and neither set off codes for the computer.

 

[daveanton]

IAC is about a week old, and the MAF was cleaned out

 

[97greenmonster]

You could still have gotten a faulty IAC. I bought an alternator a while back and went home, installed it, and it wouldnt charge, i returned it, got another new one, and it ran like a champ. Try that. there is a sensor problem of some sort, and only the maf and IAC or TPS could be causing this problem that come to mind. Also another idea could be unpluging the battery for 15-20 min to reset the PCM.

 

[Rottie]

I agree with resetting the computer. Also, I suppose you could have a vacuum leak somewhere. That caused very similar problems with mine. Listen for a hissing noise under the hood. Check the vacuum hoses under the battery and behind the engine on the firewall. There are several places that can develop a leak.