High idle and weird idle surge

[shotyme92]

My 92 ATX developed a weird idle surge and high idle when coming up to stop lights\signs. It would go 800-1500 3-4 times and then idle to 1200 steady. Took it in and they said MAF was bad so i replaced it and now it doesnt surge at stops anymore but it did retain the high idle and now when i start it cold it runs really funky, surges between 1000-1500 and when its down around 1000 its sounds like its missing on a couple cyliners. Takes about ten minutes for this nonsense to stop then it idles at 1200 steady.


Any ideas for me?

 

[shotyme92]

excellent!

 

[LOUDSHO92]

Probably the IAB needs to be cleaned or replaced.

Codes might help.

 

[shotyme92]

could it be that easy?

 

[rubydist]

I would first perform the idle reset procedure to be sure that its not just the pcm being confused by the new mafs. If that doesn't do it, then the iac is the most likely candidate.

 

[LOUDSHO92]

could it be that easy?

You asked for help. If you want I can give you a 30 step procedure that won't fix anything but give you something hard to do. :angelnot:

If it doesn't work its a very good place to start. Like I also said pulling codes might help as well.

The IAC is the Idle Air Control so it does control the idle... I have had the problem before.

 

[SHObill]

Pull & clean the IAB & make sure you don't have ANY vacuum leaks like loose TB hose, cracked/disconnected vac lines.

 

[shotyme92]

I did try and reset a couple times, I'll dig into that IAB first thing tomorrow. Thanks

 

[shotyme92]

Had an extra IAB in the shop so I cleaned it up and installed it but still no change. Looked all over for a possible vac leak and turned up nothing. I will keep going on it I guess until I find the problem. Any other ideas welcome.

 

[SHOmethewayhome]

my 87 F150 does this, and the IAC is brand freakin new. cant find a vacuum leak, but judging from the original looking vac lines, there's one to be found somewhere.

 

[shotyme92]

Thats what I figure. I plan on pullin my intake and valve covers for PC sometime soon so I will do some more inspection at that time.