Anyone else haveing this problem ???
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Joined: Sep 2005
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Anyone else haveing this problem ???
1996 lt1 wont idel down right way. driving along at say 40 mph .. let off gas and it will idle down to about 1200 rpm...and it wil cruse along that that for a long time....
come to a stop and it idles down to 800 rpm... shift to neutral and it seems to idle down like it should. Its almost like a carb with a fast idle/ choke. I have replaced the TPS / IAC / and flue pressure sensor. All cables seem to be working as they should. Really confused on this one.. Thanking you for all you help in advance. R
come to a stop and it idles down to 800 rpm... shift to neutral and it seems to idle down like it should. Its almost like a carb with a fast idle/ choke. I have replaced the TPS / IAC / and flue pressure sensor. All cables seem to be working as they should. Really confused on this one.. Thanking you for all you help in advance. R
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
I think you do have a problem. I am familiar with that scenario on other cars where they do hold the idle higher while in motion. When the car stops the idle reduces. I think this functions might be in regard to emissions. But yours sounds like an aggravated condition.
I don’t have an exact answer to the problem but emissions might be a place to start. Look at sensors EGT, solonoid, etc. Look to see if a code is set, you don’t necessary have to have a SEC light come on to have a code set. Have you had a gas mileage change, O2s?
I don’t have an exact answer to the problem but emissions might be a place to start. Look at sensors EGT, solonoid, etc. Look to see if a code is set, you don’t necessary have to have a SEC light come on to have a code set. Have you had a gas mileage change, O2s?
Last edited by pcolt94; Oct 2, 2008 at 11:20 AM.
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
What kind of trans? Unless it is a manual in neutral, the engine is being driven somewhat by the tranny in coast mode.
1996 lt1 wont idel down right way. driving along at say 40 mph .. let off gas and it will idle down to about 1200 rpm...and it wil cruse along that that for a long time.... come to a stop and it idles down to 800 rpm... shift to neutral and it seems to idle down like it should. Its almost like a carb with a fast idle/ choke. I have replaced the TPS / IAC / and flue pressure sensor. All cables seem to be working as they should. Really confused on this one.. Thanking you for all you help in advance. R
come to a stop and it idles down to 800 rpm... shift to neutral and it seems to idle down like it should. Its almost like a carb with a fast idle/ choke. I have replaced the TPS / IAC / and flue pressure sensor. All cables seem to be working as they should. Really confused on this one.. Thanking you for all you help in advance. R
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Thread Starter
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Joined: Sep 2005
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I think you do have a problem. I am familiar with that scenario on other cars where they do hold the idle higher while in motion. When the car stops the idle reduces. I think this functions might be in regard to emissions. But yours sounds like an aggravated condition.
I don’t have an exact answer to the problem but emissions might be a place to start. Look at sensors EGT, solonoid, etc. Look to see if a code is set, you don’t necessary have to have a SEC light come on to have a code set. Have you had a gas mileage change, O2s?
I don’t have an exact answer to the problem but emissions might be a place to start. Look at sensors EGT, solonoid, etc. Look to see if a code is set, you don’t necessary have to have a SEC light come on to have a code set. Have you had a gas mileage change, O2s?
Melting Slicks
Joined: Jan 2002
Posts: 2,238
Likes: 4
From: Milan
Are you with the lever selector in OD ?
Try with th elever in D
If you let gas at 40 mph you shold feel engine braking -Overrun- .
If In OD It's normal, it's due to iac steps added in motion.
There is a table with steps added vs. speed.
Try with th elever in D
If you let gas at 40 mph you shold feel engine braking -Overrun- .
If In OD It's normal, it's due to iac steps added in motion.
There is a table with steps added vs. speed.
Racer
Joined: Feb 2008
Posts: 269
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From: Victoria British Columbia
Have you checked the voltage from the IAC valve and the TPS? With throttle closed the TPS voltage should be 0v - 0.5v and I cant find the voltage for IAC but it should be between 5 - 45 counts on a scanner. You can pull the IAC out and clean it with contact cleaner, sometimes they get gummed up.
Instructor
Joined: Nov 2006
Posts: 100
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Fast Idle
Just read your post with interest as I had the same problem for about six months, thought I tried everything until I decided to do the throttle bypass mod, although I have also installed a new BBK throttle body as well the problem is now history, mine is a 1996 CE Coupe.
Le Mans Master
Joined: Feb 2003
Posts: 9,087
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From: Chicago IL
I had a 2004 GTO 6spd that did the same thing.
