High idle

[nickvash0104]

I just went out this morning to reset my ignition timing - found out that it was set to 5? instead of the normal 10? - and after resetting it, it was idling at ~1600 -- way too high. It was a solid 1600, but even after warming up, it still rested ~1000, 300 off from the standard 700. ISC? MAF? IAT Sensor? Or something I'm totally missing... I cleaned my ISC about 2 months ago, tested my MAF 1 month ago as well as my IAT sensor. O2 sensor is ~3 months old.

I couldn't find anything in the TSRM that dealt with a high idle; only rough / erratic, but mine is smooth. Ideas?

[rnoswal]

There should be an air screw on the front side of the intake manifold just right over the butterfly. Try screwing it in some and see if that helps. You might have knocked off a vacuum hose, but that amount of timing sounds like just a turn or so on that air screw should do it for you.


Russ

[suprra_girl]

did you do the ign timing with the diagnostic pins connected?

yea i would try vacuum leaks.... do you have an aftermarket boost gauge?

get some carby cleaner and spray around the intake and vacuum areas and see if your idle changes

if it does... you've found your leak

[nickvash0104]

Actually, I've got an NA No turbo here...

I'm fairly certain I have a leak somewhere along my intake as it's starting to crack around the lip of the angle tube - I'm still looking for a replacement aftermarket solution, but for NAs, there seems to be very little that has just the tube.

[suprra_girl]

ahhh k i'll reword it... if you had an aftermarket vacuum gauge you could see what your vacuum is at idle and you'd know straight away if you had a leak

if you have any cracks in piping between the afm and throttle body or intake manifold leaks or vacuum leaks this will screw with your idle

[rnoswal]

A possiblity until you find another tube is to put some silicone on the cracks. That will seal them up, plus remember the vacuum hose under the tbe that connects to the power steering pump. It is just a bit easier not being turbo charged in finding a leak, but there are a lot of vacuum hoses to check, so the spray is the easiest way to check it out. Even an open EGR valve will mess with the idle.


Russ

[nickvash0104]

I'd adjusted the screw - you're talking about the one near the throttle body, right? I adjusted it to the lowest RPM position and it's still idling too high (I knew it was the lowest RPM position because the other direction revved the engine higher)

[WiseAssJester]

The cams still stock? On a larger motor a massive cam will bump the idle up. My 350 has to idle at about 11-1200 after warming up to keep the lope from the cam from killing it.

[nickvash0104]

Yep, still stock - only thing that isn't stock in regards to engine parts is the air filter.

[rnoswal]

If you have that idle adjuster screw all the way in then you have either an air leak or the ISC is not functioning. You can hear the ISC clicking when you turn the A/C on and off, it should do a little clicking, but that still won't guarantee that it is working. If the computer senses that the car is always cold then it will keep the idle up too, there is a sensor for that too. Still sounds like a vacuum leak though. Make sure that the screw you were playing with seats in all the way too. Sometimes all the carbon build up won't allow it to seat when screwed in all the way. Also, if all else has been checked, the brake booster could be leaking air. Just pinch off the hose to it to check that one out.


Keep trying!

Russ