SINCITY192

gonna test the pressure tomorrow i actually want to test it while driving around the block, but my gauge hose isn't long enough to reach my windshield. any ideas?

upon start up the jeep will rev up normal sometimes, and all the time will suddenly start idling very very low, like it wants to shut off but doesnt. usually goes back up to normal and thats when i'd pull off

ever since the shut off its been doing the sudden low idle even longer and lower

it took my about 3 times trying for it to start and when it did i burned rubber (i was holdin up traffic) but after i slow down and listened it sounded normal

and this TPS is annoying every one says its not adjusted to spec and i know this,
but every TPS, so far has not adjusted to spec,
am i supposed to keep buying TPS's till one adjust to the specs? seriously?

i mean i tried adjusting with both, fine and large adjustment screws with 2 different digital multimeters and the output wont go to the the 82% range of the input voltage which was something like 4.74 but if u need the exact specs let me know.

I also wondered if a clogged cat could be causing this?

SINCITY192

by the way its a xj 88 6cyl 4.0

any ideas?

reddragon72

an idle problem has nothing to do with the TPS. you need to check the ABV air bypass valve, also known as the ICV idle control valve. that is the only thing that controls idle, the TPS is only in effect when you step on the gas.

SINCITY192

is the Idle control valve the IAC?

reddragon72

sorry about that, but yes they call it the IAC Idle Air Control. It is on the throttle body opposite of the TPS if I remember rightly. replacing it is not the only thing you have to do, you have to carefully clean out the chamber it fits in and not scuff it up or nick it cause if you do it may jam in the chamber and not work. Try removing it and cleaning it before you buy a new one cause any small amount of gunk can cause it to get stuck...

SINCITY192

I have mentioned this problem in so many forums i forgot to mention that i already brought a new IAC back last summer but since you mentioned it i dont recall the machanic in the shop ever spraying or attempting to clean anything.

so i have cleaned the IAC hole and the back of the IAC as it had a little black stuff i cleaned off of it i also clean the throttle body out with some TB cleaner and the resluts were better if you ask me the car started very fast but im hoping that its a permanant fix i let u kno though

reddragon72

I have just about seen it all on my cherokee, but it is always little things(knock on wood) and those are just annoying to hunt down, but yea if the chamber that the IAC sets in is dirty then it wont work properly, and make sure the butterfly valve is clean as well as the lip it sets on in the TB, this will stop any extra air from sneaking by. One more thing to mention, that I have heard from a few people is the intake manifold warping, or at the very least the gasket goes bad, but not to many people have had that issue, but it is a possibility. But only resort to this is the IAC camber cleaning doesn't fix you issue.