Idle Issue
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 34
Likes: 0
Idle Issue
1985. The Idle seems to take a long time to come down to 580 rpm's. After starting the car, cold, it stay's around 980 rpm's for about 3 min before it starts to come down, then it take's another 2 min to drop to 580. When the car is at operating temp and you come to a stop it takes a while to come down to 580 unlike a normal running engine that immediately returns to idle. I've replaced the IAC, O2 sensor, adj the TPS (5.4v) and cheaned the throttle body. I've also replaced most of the vacuum hoses.
It's driving me crazy!
It's driving me crazy!
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Check the throttle body to ensure that it is returning to the "closed" position and not hanging up internally....a sloppy throttle body shaft bushing (usally the throttle cable side bushing gets most of the wear & tear) can cause issues such as what your describing. Other than that you have a vacuum leak some where else most likely.
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
Depends on what " a while" is. It is normal for the idle to be about 950 or so when you come to a stop and take 10 or 15 seconds to drop to about 600. This is on my 96 LT4 with 6 speed.
What you are describing on cold start is normal. At least on my car.
Last edited by MK 82; Nov 18, 2009 at 11:42 AM.
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 34
Likes: 0
Thanks for the reply's. The next step for me was replacing the throttle body. It's just that they're not cheap and I hate to spend the money if it's not the problem. But I'm not going to know if it is the problem until I replace it.
Thanks
Thanks
Advanced
Joined: Dec 2006
Posts: 53
Likes: 0
From: Newton KS
If that were the case, the idle would never drop to normal.
Depends on what " a while" is. It is normal for the idle to be about 950 or so when you come to a stop and take 10 or 15 seconds to drop to about 600. This is on my 96 LT4 with 6 speed.
What you are describing on cold start is normal. At least on my car.
Depends on what " a while" is. It is normal for the idle to be about 950 or so when you come to a stop and take 10 or 15 seconds to drop to about 600. This is on my 96 LT4 with 6 speed.
What you are describing on cold start is normal. At least on my car.
Cold start idle speed is based on coolant temperature, yours sounds about right.When I would come to a stop sign in my 85 (4+3) the idle would be about 1100 RPM's until I came to a complete stop and then it would drop down. This is how it is programmed - or was programmed. I spent the time and money to tune (reprogram) the car myself.
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 34
Likes: 0
Yes, I'm sure that there's something going on. I didn't mention that when the idle is around 800-1000 there's also a shudder which leads me towards injectors, but that's another issue, I don't believe the two are related.
85 Gold
85 Gold
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