IDLE Air Control valve

[Lift]

????

 

[TrexMex]

i removed it and cleaned it. The engine still bogged and the idle went down slightly. Im going to replace it. If that doesnt fix this problem can not having a barometric pressure sensor do it? i dont even have one. When the previous owner did a motor swap he forgot to put it in.

First time I hear about a 4.0 using a barometric pressure sensor... I thought that was calculated by the MAF sensor output? Someone else will have to chip in on this one.

So when you replaced the MAF, did you replace it with a new unit? Did you test the old one?

 

[Lift]

I didnt replace it i cleaned it. And it didnt do crap. When i went to pullapart i got the wrong unit so i didnt bother.

 

[TrexMex]

I didnt replace it i cleaned it. And it didnt do crap. When i went to pullapart i got the wrong unit so i didnt bother.

A while ago there was this guy that had the same over-revving problem and he went replacing everything around the MAF and cleaning the thing like a thousand times until he replaced it. Problem solved... Do a little search in the forum you'll find it in there about a year ago.

If you happen to have a friend with a 4.0 check and swap the MAFs and see if you fix your problem/replicate it in your friend's engine. OR just get a junkyard one and see if you have any luck with that.

I'd still change that IAC btw, too many miles on it to be trusted

 

[Lift]

oh you saw my tachometer ha? i had a swap at hundred thousand miles that motor in it now has 80 thousand on it. And thanks for the advace i will pick up a junkyard one this weekend. Ill get a mafs and a iacm.

 

[94xlt4.0]

there is no baro pressure sensor on the 4.0, it uses the maf for the info it needs. you either get one or the other unless you have a tbird supercoupe which has both

 

[TrexMex]

oh you saw my tachometer ha? i had a swap at hundred thousand miles that motor in it now has 80 thousand on it. And thanks for the advace i will pick up a junkyard one this weekend. Ill get a mafs and a iacm.

I would recommend a brand new IAC since it's a moving part that builds carbon deposits, which are the ones that makes it get stuck with time... That's my .02, You might end up where you started with a junk yard unit.

The MAF, though, that's a safest bet as long as the screws in the sensor box look untouched and the small wires are not bent or damaged.

 

[Lift]

MAFs looks good. Ill check it all out when this crappy weather is gone.