Running out of ideas SL1 intermittent high idle
 

I have a 2000 Saturn SL1 (1.9 and automatic) with 85,000 miles. Over a year ago, I had high idle problems. Upon starting, the engine went to 3,500 rpm and returned to an idle of 1,100 rpm, in about 30 seconds. Once you put it in drive and the engine went wild again. I found the intake gasket to be faulty, so I replaced it and everything went back to normal. One year later, the problem returned. Starting rpm, was 2,500-2,700 and returned to 900-1,100rpm in 30 seconds. I was upset and replaced the intake gasket again, but found that there was nothing wrong with that one. Thoughts? Thanks for any ideas, on what I should do next.

Check for a vacuum leak. Don't rule out the PCV system. Check that PCV hose for cracks.

Thoroughly clean throttle body and ensure you concentrate on the Idle air control
Also test the tps throttle position sensor. Instructions are on our site somewhere, saturnfans.com , sixthsphere.com. and a bunch of other places.

I have checked all the vacuum lines, but haven't removed the big hose, near the firewall, that goes to the brake booster. I checked the PCV, removed and cleaned the throttle body and the idle air control valve. I will have to find out how to check the throttle position sensor, but there isn't a code for the TPS. I do have a small emission leak code P0442. The gas cap seal, appears to be a problem, but I haven't replaced it yet.

Remember that the real time conditions for setting a TPS code on a 2000 s car are not necessarily the same as on a 2007 Vue, etc. The code has the same meaning, but the actual operating criteria, all of which must be met, isn't the same.

ECTS will fall open circuit. Based on how the circuit is wired, the PCM infers from its measurement that the temperature is -40 all the time. You would think this would throw a code for out of range ects measurement. It doesn't. Why? I'm assuming because -40 is within the valid range of ambient temperatures. Never bothered to look it up.

Pay a few extra bucks and get the OEM gas cap if you can. Also, very gently clean the mating surface on the top of the fill pipe with some emory cloth, being sure to block the filler opening so that none of that gets down into the tank.

Have you done a spray check with carb cleaner all over the vacuum lines or is it just a visual inspection? Not implying you missed anything but some of the cracks can be mighty small and if they are on the other side you may not find them.

I just ordered a new gas cap and will clean the filler tube opening. I failed to mention that I had replaced the air filter, spark plugs and coolant temperature sensor, before the first intake gasket change. This only made the rpm, go even higher. How do you test the TPS?

What did you replace the ects with (brand)?
Are you running the stock NGK plugs? If not, what is in there?

ECTS came from NAPA and the plugs are Autolite. The stock plugs were supposed to be changed at 66,000 miles, but Mom didn't change them. I changed them at 82,000 miles, but hadn't found the leaking intake gasket yet. After that was changed, it ran great for 3,000 miles. Now, crazy rpm again.

I am still looking for my fast idle problems. Had a PO442 code and found the gas cap was bad, so put on a new cap. Before I cleared the code, I noticed a PO122 code, I hadn't seen before. I started the engine and it went to 2,200 rpm and back down to 900 rpm, with 3 repeat starts. The other ones were 1400 and down to 1000, 1400 and down to 900 and the last one was 2,500 and down to1000. This is starting to sound like the TPS. Do you agree?

Yes. Clean the throttle body very well, keeping the engine from stalling by working the throttle from under the hood. Make sure you clean the spring of the throttle assembly as crud can get in there and hamper the movement.

Disconnect the throttle position sensor connector at the throttle body and inspect for corrosion on both the connector and the receiving pins on the sensor itself. I have seen a goofy YouTube video where the guy pulled off the connector, then gently repositioned each socket of the connector because apparently they were not all making good contact. I believe he shifted them all slightly to the left but that was probably just for his car. So make sure they are lined up and clean.

I found a TPS testing post. It ends up in the post that the TPS is not the problem but the troubleshooting steps are there. Post #2 .OldNuc (RIP) knew his S cars.

https://www.saturnfans.com/forums/sh...d.php?t=169810

Do not use an aftermarket TPS if you replace. They are universally panned by the Saturn community as they are of inferior quality and fail quickly.

This used to happen with my mid-90s S cars from time to time but seemed to come and go on its own and when it didn't a good throttle body cleaning took care of it.

Sorry for the delay in responding I'm looking for a job