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idle issue


faze23
11-25-2008, 09:59 PM
ok so my 96 eclipse started not holding idle. it would die at idle occasionally and you had to hold the gas when you started it or sat at a red light. i talked it over with my mechanic and he reccomended starting with the iac. i changed it this weekend and it worked fine untill today and it started dieing at idle again. it hasnt thrown a cel and doesnt do it consistantly. also, when the battery is disconnected for a short period of time and then reconnected, it runs fine for a few days. any ideas where to go next?

faze23
11-25-2008, 10:01 PM
sorry wrong forum......

SilvrEclipse
11-25-2008, 10:45 PM
Moved.

The IAC would be my first guess. Check the resistence in the iac motor to make sure your new one hasn't gone bad already. That will rule that problem out. Maybe clean the TB, the front o2 sensor could have an effect on your idle as well. However it should throw a cel if it was bad.

Scrapper
11-25-2008, 11:01 PM
i would have to say tps or real small vaccum leak. or you may want to get some cleaner for the housing and maf. don't use carb cleaner use the real cleaner you use for that it's made for that and autozone or advanced have it. even any store that sell automotive products. add sea foam also.

SilvrEclipse
11-26-2008, 10:11 AM
He has a gs, 420a motor so no maf. A vac leak would cause it to idle high not die out.

faze23
11-26-2008, 10:19 AM
how would i go about checking the resistance in the iac?

SilvrEclipse
11-26-2008, 10:32 AM
Volt meter. I would suggest you invest in a shop manual for your car. That was one of the first things I bought and it helps out a lot as far as things like this. Its only like $10 at advance or something. The manual will tell you what the resistence is suppose to be.

faze23
11-28-2008, 05:05 PM
i stopped in at the local mitsubishi dealership to ask some of their techs about what path i should follow on my idle issue. they advised me to clean the throttle body and computer grounds. if neither, they think my computers fried..... this is gonna be a long weekend, ill keep ya posted

SilvrEclipse
11-28-2008, 06:43 PM
I wouldn't be jumping to conclusions about the ECU being bad. While its possible that could be the problem I would be betting on a problem somewhere else. Most of the time when ECUs go out that make the car do random things, not just screw up the idle.

faze23
11-29-2008, 10:36 AM
i need to check the grounds tonight, that could explain why the cel codes arent being held and when the battery is unhooked and then put back in it runs fine for a few days.... need more time off from work:popcorn:

faze23
12-02-2008, 04:07 PM
so far ive replaced the iac, cleaned the throttle body, and replaced a cracked vacuum hose.... still not holding idle. im goin to a friends shop 2nite to have it hooked up to a scanner, hopefully its somethin small and stupid ive overlooked:bricks1:

faze23
12-03-2008, 09:07 PM
had my mechanic scan it, turns out the o2 sensor was reading 0.5 constantly....

faze23
12-05-2008, 03:39 PM
front o2 sensor seems to have fixed the idle
thanx silvreclipse, you called it.

david-b
12-05-2008, 04:32 PM
i need to check the grounds tonight, that could explain why the cel codes arent being held and when the battery is unhooked and then put back in it runs fine for a few days.... need more time off from work:popcorn:

Glad to hear it's fixed.
However, I need to clarify the above quote. When you disconnect the battery, the ECU is reset, erasing all saved codes and resetting all settings back to normal. Like you said, the O2 was bad and the car ran fine with just the reset. It's running tests on it's self and I heard it takes about 50 miles or 2 hours of continual driving (or idle) in before the car starts making the adjustments and running in an open loop. When it's first connected though, it's running on how the car was programmed to run, not running based on it's surroundings. That's also why it's technically good to reset the car each time you add any mp-worthy mod. Hope that makes sense.

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