blackztpi

I've been working with ion from madz28.com on a tune and nothing has worked as far as fixing my problem. here's the deal. (all problems have loccured on setup listed below).
if you floor it through a couple gears and then push in the clutch or pop the trans in neutral, it will idle at 2k rpm and nothing will bring it down. if you shut the car off and restart it, it continues to idle again at 2k rpm. it takes a couple minutes of more to fully come down off of high idle and return to normal. if driving normally, the idle still comes up to about 1700 rpm and then comes down to normal after 5-15 seconds. Even if you are traveling at 1500 rpm, the engine will return to 1700rpm or so if you kick in the clutch. ??
i do not have a bad IAC and the throttle body is not sticking open. i have the throttle body set screw set as low as it will go without making the rpm too low to operate.
Ion from madz28 tunes says there is nothing more he can do in the tune to help this cause. I'm really lost on what else to look into...has anyone else had this kind of problem? when i first got the car going after the engine rebuild, it drove like a dream. i never had any high idle problems until i floored it for the first time. ???

Injuneer

Have you done a scan to see how the PCM is trying to move the IAC valve? As RPM increases, the IAC counts increase. As you slow down, the PCM should drop the IAC counts and the IAC should close to bring the RPM down. If for some reason the IAC was slow at closing down, it might explain the problem. Have you checked for dirt on the IAC pintle? How did you determine the IAC is not "bad"?

blackztpi

i have'nt had access to a scan tool good enoguh to give me live data readings. i intend to find one or buy one here soon. as for the IAC, i took apart and cleaned the stock IAC thuroughly, thinking this may be the problem. i continued to do the same thing. i was getting a little more resistance from the IAC on the ohmmeter than the book stated so i replaced it with a new one i got from autozone. The problem still remains. where would i look in the scan tool to get live readings from the IAC circuit? I don't recall being able to find those tables easily on the Tech 2 scan tool.

blackztpi

If for some reason the IAC was slow at closing down, it might explain the problem. Have you checked for dirt on the IAC pintle? How did you determine the IAC is not "bad"?[/QUOTE]

also, the car does NOT gradually fall in rpm until it hits normal idle. it will, for example, stay at 1700rpm for 10 seconds straight or so and then all the sudden drop from 1700rpm to regular idle. The dropping process only is about 2-4 seconds until it hits normal idle. it's like it's triggered or something. And i the IAC was doing something wrong, why would WOT trigger it? like i said before, i never had idle problems until i floored it for the first time. thanks for the info.

blackztpi

Bump?

blackztpi

I've had suggestions of a possible vaccum leak... any thoughts?

blackztpi

injuneer, what do you think i can look for as far as vaccum leaks or iac faults??? thanks

dr97z

I would get it on the scanner and check the TPS voltage before doing anything else. I had the same problem except with an automatic and it only did it at WOT runs and would mess with the tranny and wouldn't idle down for nothing. TPS was bad, night and day difference after changing it out. Just a suggestion though.

crAzy95z28

go clean ur IAC sensor along with ur TB. not a hard job, just about 30 min of your time.

I did this to mine and my high idle went down.

blackztpi

sounds good, but i have a new IAC, throttle body is already cleaned, and the tps is also new as of late last year

OBE1 95Z28

I had an issue with my rpms hanging after cleaning my TB. The blades looked closed to me when the rpms would hang. I ended up dabbing some oil on the butterfly rod where it meets the body of the TB and the problem was solved.

EVERESTZ28

i used to have a similar problem, was my TB it apears all right, it stop at the screw when returned but if you pushed it hard with the hand it moved a little but enougth to down the rpms, i added a point of cold solder and fixed it.

blackztpi

i don't think itsthe TB. i wound the return spring one extra time so it definately closes

OBE1 95Z28

I thought mine was closed too! Easy enough to try to lubricate the rod. I just used a Qtip to dab some oil on the rod and exercised the butterflies open and closed a few times.

blackztpi

its not the TB. when it was idling high, i manually pushed it with my fingers. nothing changed