Questions about TPS and IAC

[Dober89]

Alright I just tried adjusting my TPS sensor on my 89 5.7L TPI and its not even close to what the haynes manual says. I jumped the wires and stuff and its supposed to be around 0.54 volts and im reading 4.98 volts.

Also how can I tell if my IAC is still in good working order??? Im wondering if that has anything to do with my 600 idle.

[89IROC&RS]

um..... i think youre doing the TPS wrong. the TPS is not adjustable, and is not a constant voltage device, there should be three wires, a power with a 5 volt reverence signal, a ground, and the signal wire that sends out anywhere from .5 - 4.5 volts, with the voltmeter hooked up to the signal wire and a ground, move the little arm from one side to the other and watch the voltage change.

also, whats wrong with a 600rpm idle???? where do you think its supposed to be.

[DaMoNe6969]

600 idle sounds perfect..

But as 89 said the TPS isnt adjustable, and to check your IAC, just take it out (really big wrench) and check to see that the pintle moves in and out with a little pressure..
There is a way to jump power to the terminals to get it to move in and out, but im not sure how

[DaMoNe6969]

Is it idling smoothly at 600? or does it sound like it wants to die

[Dober89]

The TPS is adjusted by loosening the bolts and rotating it forward or back which changes its relation with the arm that is attached to the throttle body.

I think it should idle around 800 or 900.

Whats messed up is that I get a reading of 4.98 from the TPS, but at closed throttle I should read around .54 and at WOT it should be close to 5.

Mine doesnt change at all when I open up the throttle blades so im wondering if the TPS needs to be replaced.

[89IROC&RS]

if it dosnt change when the arm moves, its bad easy

[DaMoNe6969]

900rpm idle seems high?

But it does seem wierd that the resistance on your TPS doesnt change with the throttle.. as you mentioned, the resistance should get higher, the closer you are to WOT.. Unless your TPS is set so far off that at idle, it thinks your at WOT???

[Dober89]

Im not gonna bother with my IAC cuz ive been told its easiest to do it with a laptop hooked upto the car.

1990-1992 had non adjustable TPS.

[DaMoNe6969]

oh ok.. I know mine doesnt but I guess that would explain it

[Dober89]

When the throttle blades are closed its supposed to read around .54 like I said but mines .26 and I cant move it up or down.

When the car is idling it sounds like its about to die. It wont even stay running when I first start it up. I have to stick around for a min or so and give it some gas.

[DaMoNe6969]

loosen up the TPS and start the car.. See if you can adjust it like that.. Sounds like youve got a bad TPS though

[89IROC&RS]

yeah id say that its out of range, and has inadequate activity. id replace it and see if it fixes the idle problem.

[Dober89]

At carparts.com they have 3 different ones. Borg Warner, KEM, and Standard motor products.

Borg warner is the most expensive but is there any difference??

[Savage Messiah]

... my idle is usually around 1000-1500... im guessing this isnt normal?...

[DaMoNe6969]

Borg Warner would be the best choice.. Never heard of the other two.. Probably only better in terms of Long term reliability