Random, high idle?

[RysRed96GT]

My 96 GT has recently been having an issue where, with my foot OFF the gas, it would start to idle high. It does this about 3/4 of the time and it can idle high anywhere between 1200 to 2000 RPM, sometimes fluctuating in between. Sometimes it will go back down to around 800 on its own. Also, sometimes I'm able to flip the throttle and it goes back down.

I've already replaced the IAC. I do have a MAF with the post removed (I have my old one but got this for next to nothing), but don't believe this was happening prior to it.

One thing I've noticed is it has done it more since it has gotten colder. Could it be the temp sensor in the intake tube? Could it be a dirty MAF sensor? The hoses were checked out by a mechanic and looked fine. Any ideas? Thanks.

Ryan

 

[HOOCBB]

2 thoughts...

first thought, if you can identify a mod where it started doing this, undo that mod and see what happens. A MAF is simple to replace for testing purposes, especially if you still have the stock unit.

As a secondary thought on the MAF, are you using the stock MAF electronics in a different housing or is it a whole new unit? If it's a different assembly, are you sure the MAF is calibrated for whatever size injectors you have? I don't know that a mismatched MAF would cause your problem though...

2nd thought, did you happen to clean the TB when you replaced the IAC? Pop the hood and mess with the throttle blades a bit. If it feels like the butterfly isn't closing all the way without a little (delicate) help, then you need to clean the TB. It's not uncommon for a buildup of carbon deposits to keep throttle blades from closing completely.

Good luck

Oh and maybe clean the MAF while your at it...couldn't hurt, right?

 

[bhuff30]

Vacuum leaks can be very confusing. Before spending any more money, spend some time checking the vacuum hoses and listening carefully for vacuum leaks.