Engine stalls when returning to idle.
Thread Starter
12 Second Club
Joined: Nov 2005
Posts: 407
Likes: 1
From: Rockwall, TX
Engine stalls when returning to idle. OK here's the setup:
2002 SS Camaro/A4
48K miles (I'm the original owner)
Rarely driven (cruising, race track and back ~1000 miles a year)
Other than the following, the car is bone stock:
MT Drag radials
K&N air filter
3400 RPM TQ Converter
Transmission cooler
If the car is in gear it is having trouble maintaining idle. It will idle all day long at ~600 RPM but if you blip the throttle anywhere above 1200 RPM and let go it will drop to 400 or so before climbing back up. The voltage drops when RPM goes below 500. Sometimes it fluctuates several times. Sometimes it stalls completely, usually in parking lots at low speed.
I have sprayed the TB with cleaner. I pulled the IAC motor and cleaned the dirt off of it and the hole in the TB. I removed cleaned and reinstalled the MAF sensor. I just had the computer checked and there are no stored codes.
Thanks in advance for your help.
2002 SS Camaro/A4
48K miles (I'm the original owner)
Rarely driven (cruising, race track and back ~1000 miles a year)
Other than the following, the car is bone stock:
MT Drag radials
K&N air filter
3400 RPM TQ Converter
Transmission cooler
If the car is in gear it is having trouble maintaining idle. It will idle all day long at ~600 RPM but if you blip the throttle anywhere above 1200 RPM and let go it will drop to 400 or so before climbing back up. The voltage drops when RPM goes below 500. Sometimes it fluctuates several times. Sometimes it stalls completely, usually in parking lots at low speed.
I have sprayed the TB with cleaner. I pulled the IAC motor and cleaned the dirt off of it and the hole in the TB. I removed cleaned and reinstalled the MAF sensor. I just had the computer checked and there are no stored codes.
Thanks in advance for your help.
Teching In
Joined: May 2009
Posts: 4
Likes: 0
This sounds stupid and rhudemental but the same thing happened to my car (2002 Stock Z28) My battery cables were loose on the battery. I know it is simple but it fixed mine and they didn't seem wiggly loose either the were pretty snug. I pulled upward on the positive side and it fixed it so I removed them both and cleaned them and reinstalled and has been good ever since.
Worth a shot and cheap fix?!?!?!?
Worth a shot and cheap fix?!?!?!?
Thread Starter
12 Second Club
Joined: Nov 2005
Posts: 407
Likes: 1
From: Rockwall, TX
I'll take a look at the battery cables. The car is 7 years old; they may need to be replaced. The factory battery leaked and was replaced with an optima red top about 4 years ago.
If that's not it, is there a way to test the IAC motor? I hate buying a new part hoping that's the fix.
If that's not it, is there a way to test the IAC motor? I hate buying a new part hoping that's the fix.
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Thread Starter
12 Second Club
Joined: Nov 2005
Posts: 407
Likes: 1
From: Rockwall, TX
The car starts like a dream. I keep the battery hooked up to a maintenance charger when it's going to sit any longer than a week.
I had the battery and alternator checked yesterday when I had the PCM scanned, and the guy didn't find anything out of the ordinary.
I tried tightening the cables last night. They were both tight. The positive cable does have some discoloration (corosion) on the insulation but not the terminals. Is there a good place other than the stealership to get a direct replacement? I can build one, I just like the factory look.
I had the battery and alternator checked yesterday when I had the PCM scanned, and the guy didn't find anything out of the ordinary.
I tried tightening the cables last night. They were both tight. The positive cable does have some discoloration (corosion) on the insulation but not the terminals. Is there a good place other than the stealership to get a direct replacement? I can build one, I just like the factory look.
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Thread Starter
12 Second Club
Joined: Nov 2005
Posts: 407
Likes: 1
From: Rockwall, TX
The IAC is mounted on the throttle body. It acts like the idle bleed screw on a carburator, only the computer makes constant adjustments to it. It has a plunger that moves in and out to adjust the ammount of air allowed into the throttle body and therefore idle speed. It's the reason idle can not be adjusted without a computer tune.
Ive been having the exact same problem, esp in stop and go traffic the car would idle anywhere from 400-1000rpms and has stalled a few times. Do you have a part # for the IAC? Thanks in advance!
