Started having a high idle problem (1100-1200rpm) on 91 f150 after last tune up. Cleaned IAC valve and reset computer, but didn't help. As far as I know, all vacuum lines are good and properly connected. I want to clean MAF sensor but can't locate it. I looked all around filter box and hoses all the way to the throttle body. Please help!

ps. I plan on checking/changing TP sensor if cleaning MAF doesn't help.
thanks cp

 

Forgot this info: 91 f150 302 v8

cp

 

There's no MAF on a '91 unless you have swapped it out. I see you cleaned the IAC, which is a good start, and I would also clean the throttle body with throttle body cleaner, and maybe even use an old toothbrush. TPS would be a good thing to check as well. Also look for vacuum leaks.

 

I dont think you have a maf sensor. i think ford started putting them on in late 1994. You should have a map sensor, which isnt cleanable. Did you try testing or checking out you TPS (throttle position sensor) that may be the cause or your idle problem.
Dave

 

hsdave, epnc: Thanks for the info. I feel better now about not being able to find the MAF sensor! I think I'm going to pull the throttle body and upper air intake off. Then I can clean the TB and check all the vacuum lines. How do know if the TP sensor is bad? Also, how do you know if the iac valve is bad? I noticed the spring in the iac valve seemed weak but I have nothing to compare it to.

It's just strange that this started after the tune up. Was also messing around with the egr valve at that time.

Not getting any codes now (koeo,koer), but did flash an engine coolant temp sensor out of range once. I read that that also controls idle speed.
thanks cp

 

See if you can get your hands on a Haynes manual. It has lots of tests in there for EGR, TPS, etc etc.

 

Thanks epncsu. I'll do that. Been going by a Chiltons manual but it often assumes the user is experienced and knows what and where they're talking about.

cp

 

I have both a Haynes and a Chilton, so I can bounce between the two. It helps sometimes when you can't figure out what they are saying in one, the other may be more helpful. Good luck.