Idle Problems
Thread Starter
Instructor
Joined: Sep 2000
Posts: 142
Likes: 0
From: Apple Valley MN
Idle Problems
At full temp, my '93 idles at 12-1500 rpm's. I kick it down and the idle drops to about 750. Next stop light and I push in the clutch, 12-1500 rpm's again. Kick it down, 750. Any idea why I have to kick it down to get it to drop below 1000 rpm's? IAC?
Thanks!
Thanks!
Safety Car
Joined: Apr 2002
Posts: 4,732
Likes: 2
From: Yes .....VA
Re: Idle Problems (bob_ev)
Throttle Position Sensor?....I may be way off here.. but on my 91 I had a similar problem and was throwing a code 22.....my sensor was unplugged...plugged it back in and all was well. :)
Advanced
Joined: May 2002
Posts: 61
Likes: 0
From: Seaford NY
Re: Idle Problems (vette5)
I was in a similar position with my '86. I got some great advice from another forum member (Rich. B) who said it may be the throttle body sticking or having bad bushings.
In my humble opinion, I would go to a parking lot and juice the gas until it sticks, then put into neutral, set the parking brake, and pop the hood.
If the idler is not touching the idle set screw then it's a mechanical binding and not an IAC of TPS issue. If this is the case then the bindpoints are
1: The throttle cable
2: The throttle body
3: Cruise Control cables.
I hope this helps,
--Jeff
In my humble opinion, I would go to a parking lot and juice the gas until it sticks, then put into neutral, set the parking brake, and pop the hood.
If the idler is not touching the idle set screw then it's a mechanical binding and not an IAC of TPS issue. If this is the case then the bindpoints are
1: The throttle cable
2: The throttle body
3: Cruise Control cables.
I hope this helps,
--Jeff
Thread Starter
Instructor
Joined: Sep 2000
Posts: 142
Likes: 0
From: Apple Valley MN
Re: Idle Problems (advcomputer)
It seems more mechanical. The screw is not touching. If I push it with my finger, it goes back and the idle drops down to 750. I wasn't sure if there was anything by design that was keeping it from coming all the way back. The car only has 33k miles on it so the throttle body bearings should not be worn out. I cleaned the throttle body and it seems not to be binding.
Maybe cable related? OR maybe the spring is weak?
I'll check out the cables for any binding.
Thanks for the ideas!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Idle Problems (bob_ev)
It may be binding in the linkage or throttle plates but my first bet would be the IAC.
If you don't detect any linkage binding and the TPS resistance reading increases uniformly as you slowly increase the thorttle position, pull the IAC motor and clean it's bore. Then reset min. idle speed.
If you don't detect any linkage binding and the TPS resistance reading increases uniformly as you slowly increase the thorttle position, pull the IAC motor and clean it's bore. Then reset min. idle speed.
Advanced
Joined: May 2002
Posts: 61
Likes: 0
From: Seaford NY
Re: Idle Problems (65Z01)
I forgot to mention one other "bind point" that I believe is possible.
The TPS is connected to the same "shaft" as the throttle plates. I would assume if their was an issue with the TPS binding that it would cause the same issue.
Mine has gotten so bad that I can duplicate it at will. I can be sitting in the car at idle. Juice the gas to 2100 and keep it their for 5-10 seconds the just back off the gas and it will hang at 1200, 1400 or even 1700 RPM.
--Jeff
The TPS is connected to the same "shaft" as the throttle plates. I would assume if their was an issue with the TPS binding that it would cause the same issue.
Mine has gotten so bad that I can duplicate it at will. I can be sitting in the car at idle. Juice the gas to 2100 and keep it their for 5-10 seconds the just back off the gas and it will hang at 1200, 1400 or even 1700 RPM.
--Jeff
Burning Brakes
Joined: May 2001
Posts: 1,036
Likes: 0
From: Plant City Fl
Re: Idle Problems (bob_ev)
Just had the same problem with my 88, 38,000 miles Turned out to be the throttle cable was sticking. A little graphite lubricant on the cable, and all is well. Hope this helps. :yesnod:
7th Gear
Joined: May 2002
Posts: 7
Likes: 0
From: Crescent PA
Re: Idle Problems (Bob88Convertible)
Had simular problem on my 87. Usually at 40,000 miles the throttle plates on the back side get carboned up also the lower IAC Coolent cover inside gets carboned up. Remove air cleaner cover and open fully the Butterfly valve ck for carbon on the back plates. If carboned up remove t/b and use a good carborator cleaner. If you remove t/b clean the intake chamber with a long cleaning brush and clean the MAS solonoid valve in the rear. You will need a gasket kit--the six screws that hold the IAC coolent cover are usually corroded may have to be ordered. One last thing remove the IAC valve before cleaning.
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