I don't think the TPS is your problem so there's no sense wrecking it. I would say you probably have a vacuum leak or a throttle that's sticking open slightly. Have you cleaned the throttle body yet? Checked for sticking cables?

It's possible the IAC is also bad (you did an electrical test, but that doesn't tell you anything about the mechanical condition of it), but you are archiving a normal idle speed.

The proper way to backprobe a connector is with pins. Paper clips are too thick to fit. Borrow some sewing pins from your wife.

I should also add, if you use a scan tool you can read the TPS voltage straight from the computer without even opening the hood.

 

First, thanks for response. Don't see how could be vacuum leak, because the rpms wouldn't go down while idling from 1700 to 750 would it. wouldn't the vacuum stay constant unless i accelerated or decelerated engine?

My intuition tells me that the tps is not it, especially since another told me that 99% of the time it is not a TPS issue. Right a sewing needle or maybe a safety pin could be used as an insert. but don't believe i will go after the tps..

And right the iac could still have a mechanical issue. I thought of cleaning it but thought again, imagining that cleaning may make it worse. Any thoughts?

Don't see how could be vacuum leak, because the rpms wouldn't go down while idling from 1700 to 750 would it. wouldn't the vacuum stay constant unless i accelerated or decelerated engine?

 

First, thanks for response. Don't see how could be vacuum leak, because the rpms wouldn't go down while idling from 1700 to 750 would it. wouldn't the vacuum stay constant unless i accelerated or decelerated engine?

No. If the vacuum leak is not huge the IAC can adjust for it by cutting off more air. If you did have a vacuum leak, you will usually get lean codes. So is the CEL on at all?

In my experience cleaning the IAC won't make it worse, but sometimes it doesn't make it any better. If you do clean it, keep the solenoid end up so liquid can't run down the shaft.

 

^+1 on cleaning/replacing the iac.

 

thanks for response. good explanation about why a vacuum leak can be handled by the iac for smaller leaks.

i have no CEL on.

You said keep solenoid end up when spraying. i know a selenoid is winding wire and a magnet. so can you visualize the solenoid to see it>

 

Prop or hold up the end opposite the hole(s) on the bottom you'll be spraying into.

 

ok, thanks. interesting enough the auto parts didn't have a gasket for 03 sable iac. tried autozone, napa, advance auto, pep boys. down in south florida. i do believe i found one for a 99 taurus that looks similar. will have to go and look at it.

gasket looks thick, 1/4 inch. in my car the iac, appears to be flush and only allow a gasket about thickness of 1/16 or 1/8 inch. Does anyone remember the thickness of the gasket?

 

There are groves the gasket fits into, so the actual standout is much less than the thickness of the gasket.

 

ok, i just got back from under hood and sprayed hoses and anywere else that i would suspect vac leak. know engine idle change.

i read on another thread within this forum that a guy sprayed and cleaned his iac and next thing he knew the CEL light came on without solving his idle problem.

I wonder what happened. I don't want my wife saying something like "you should have left it the way it was" if all of sudden the cel comes on. but i went ahead and bought the gasket anyway.

 

Check your throttle and cruise control cables. I am wondering if one of them is binding up.

 

Right, i checked both. thanks for trying to help out.

 

Any build of crud around the throttle plate?

 

thanks for inquiry. i didn't see any crud. the butterfly sits at 90 degree, no tilt to it to keep it open.