Author Topic: How do i set the base idle? (Read 4151 times)

Screaming M42 · « **on:** December 28, 2008, 11:58:09 PM »

My car wont pass smog for anything. the hydrocarbons are ridiculously high.

tonight, i just changed out what appears to be the original 130k mile o2 sensor. hopefully that will. help. i also replaced all the vacuum hoses. what a difference! i also rebuilt the head, new rod bearings all new seals, oil pan, front/rear main seals. car drives like a dream now. the car did have a blown head gasket when i bought it.

however, the idle still searches. it hovers around 900, which i found to be odd. so i shut the car off, and disconnected the ICV. started it up and it idles at 1500!! i looked at the throttle body and it seems pretty obvious what to do mechanically. but is there a certain procedure i need to follow?

roundel318 · « **Reply #1 on:** December 29, 2008, 12:24:58 PM »

Have you cleaned out your ICV?
Are you certain its not backwards?
I presume your new vacuum hoses for this are new too?
How is your TPS?

Screaming M42 · « **Reply #2 on:** December 29, 2008, 01:40:32 PM »

I have changed all the vacuum hoses, including the ICV and im pretty darn sure (ok, ilooked at it and at pictures of others and its correct) its not backwards. i have not cleaned it. i did the tap test and it responded beautifully.

i have not checked the TPS. how do i go about doing that?

also, i am taking the car to get a new cat installed today.

roundel318 · « **Reply #3 on:** December 29, 2008, 01:50:53 PM »

This thread has a TPS rehab article....
http://www.m42club.com/forums/showthread.php?t=7553

Screaming M42 · « **Reply #4 on:** January 01, 2009, 11:13:37 AM »

the new cat did it!!! it passed smog! with 813 of 815 allowed NO (PPM)

the last year of my life hasnt been a waste..

tjts1 · « **Reply #5 on:** January 01, 2009, 02:33:53 PM »

For future refference, make sure the engine is at full operating temp before smogging the car. I had a shop smog my car with the engine dead cold. It passed HC with 814 out of 815 max.

nuvolarossa · « **Reply #6 on:** January 02, 2009, 03:43:55 AM »

ok, and the idle is still high?
The other day I was trying to wire a piggyback ecu and I inverted the wires on the throttle body potentiometer. The result: idle at 1300-1500revs and ecu error stored

So check the throttle body potentiometer with a multimeter, here is how it should be:

Screaming M42 · « **Reply #7 on:** January 02, 2009, 08:27:47 PM »

tjts1, the car was extremely hot. i made an appointment at the smog place. took it through a canyon, got the engine really hot and stuck it on the rollers. still barely passed. i will worry about it again in 2 years haha.

oh wow! thank you, nuvolarossa, for the chart. i will work on that tomorrow and let you know if it works.

roundel318 · « **Reply #8 on:** January 02, 2009, 10:15:29 PM »

good that cat got you lined out.
a friend of mine had a plugged cat in his saab, threw errors and ran like ass