View Full Version : Idle problem!?!?! :(

- January 3rd, 2003, 08:33 PM
Hello everyone.. I am new to the board. About six months ago I flew to Florida to purchase my 1992 Dodge Stealth RT. I had everything checked out at the Mitsu dealership and they said everything was perfect. When I got the car there was a clutch problem.. which I paid out of my ass to fix. Recently this idle problem started. It started out by going below 1000 rmp to die out unless I kept giving it gas. Soon after that it stopped dieing out and started jumping from 3000 back down.. back up again constantly. It doesn't jump anymore.. basically it stays inbetween 2000 and 3000 rpm's. I am about to have the problem diagnosted at the dealership. Any suggestions to what the problem is? Also there is some sort of a cooling problem. It will overheat unless it is totally completely full with coolant.. otherwise its fine.. whats the deal with that? Thanks a lot for any suggestions!


- January 3rd, 2003, 09:52 PM
Try to have the o2 sensor replaced. It may be tired only.

- January 9th, 2003, 06:44 PM
OK took it to Mitsubishi for a diagnostic. They said the problem was the Idle Air (Speed) Control motor $336 for the part..$426 with labor. Does anybody know a little more about that. Where I could possibly get the part cheaper? Is it hard to replace? Any info would be greatly appreciated. Thanks.

- January 9th, 2003, 07:49 PM
"The IAC, Idle Air Control (you will also see it called ISC) is a DC controlled stepper motor. The ECM uses it to vary idle speed. AC, electrical load, power steering etc will cause the ECM to change the step count. You may need to reset base idle after an IAC change."


"I thought I had a problem with mine, so I took it apart and cleaned it. Turned out the problem was bad O2 sensors and a dirty throttle body and plenum. After new O2's and a thorough TB cleaning (and Seafoam treatment) my idle is stronger than ever. I suspect a lot of problems people have with a bad idle speed are misdiagnosed as the IAC motor. It's very expensive to replace and I'd try everything else I could think of before I bought a new one. The manual has a procedure to test the IAC motor."

"If you take out the IAC (bit of a PITA to get to the bottom screw) you can clean it with carb cleaner. I just cleaned mine two days ago and it fixed the problem I was having (car would shut off after I started it). Just pull it out - it'll be black and nasty looking. Take the carb cleaner and spray some on a rag or on the end of the IAC and rub it for a bit. It should clean it right up."

"Get a new Idle Control Servo. That WILL fix it. No question. Call Tall Mitsubishi and ask for part MD628053. Tell them you are a 3Si member and they will put it to your door in two days for ~$250. It's not cheap, but that is the solution. The ICS on my VR4 went out. It would work fine until the engine got warmed up and then my idle would just wack out on me. I swapped it with the one in my base coupe. It acted fine in the base coupe for a few days then it totally crapped out regardless of the operating temp. I ordered one from Tall Mitsubishi and within 15 minutes of it arriving the car was idling like a champ."

This is what I found. I will try to find a link to instructions.

- January 9th, 2003, 08:14 PM
Thank you so much for the info! So you are saying it is relatively easy to remove and replace the IAC? Also you were talking about getting a new Idle Control Servo.. Same thing right? Any instructions or a link would be great.

- January 10th, 2003, 02:51 PM
Just time consuming to change out. IAC and servo = same thing.

I am trying to find detailed instructions for you. Keep checking back.

marty fawley
- March 25th, 2003, 09:21 PM
have a 93 stealth with same problem what fixed the problem??

- March 26th, 2003, 08:14 AM
Yeah. Did the problem get fixed?

- May 8th, 2003, 07:47 AM
i have a 1994 dodge stealth with a very similar problem.

i got it about 2 months ago and it would normall idle around 800 rpm. i had a bat battery - and it kept dying, so i just replaced the batterey 2 days ago.

But heres the deal. It used to idle around 800 rpm all the time. but now what happens is when i start the car, it will idle down and die unless i keep giving it gas. but after driving it a bit it dosent die, it will idle at between 2000 - 3000 RPM which is way too high.

im taking it to my local mechanic in like 30 mins, so if he gets it fixed ill tell you guys what it was. ( hopefully its not that IAC unit becuase i dont have an extra $400 :( )

- May 9th, 2003, 07:22 AM
Welp, thats what it was. IAC..... that SUCKS. the bill with labor is going to be $450.

- May 9th, 2003, 12:04 PM
Find a used one and replace it yourself. Not that hard.

- June 30th, 2003, 11:50 PM
could have just bought an O-Ring for $0.25. That was my fix. The O-Ring on the IAC tends to melt after a while, and needs to be replaced. You could have saved a nice chunck of change by doing that first. Use the www.3si.org message boards for more info. They're great on that one.