LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

high Idle!!??

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Old Apr 6, 2004 | 02:35 PM
  #1  
BLDun's Avatar
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From: Florida
high Idle!!??

You can see below what setup I have. Question is when I come to a stop and push in on the clutch to wait for a light the idle stays at about 1500 to 1800 for about 5 - 10 seconds before is finally comes down to about 1,000 where it usually idles. Any ideas why this happens?? Is it an adjustment of some sort??
Old Apr 6, 2004 | 02:42 PM
  #2  
RedWS6TA's Avatar
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From: Abilene, Texas, USA
i am having the same problem so any help would be great!
Old Apr 6, 2004 | 05:49 PM
  #3  
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From: Abilene, Texas, USA
come on. someone has had to have had this problem before. shoebox, injuneer some please give some advice
Old Apr 6, 2004 | 10:11 PM
  #4  
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I guess you and I are the only ones with this problem so if you ever figure it out let me know!!
Old Apr 7, 2004 | 12:11 AM
  #5  
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From: Spring, TX
Try cleaning the IAC valve (Idle Air Control valve).

It's attached to the bottom of the throttle body. Spray some carb cleaner in it and check for clogged air passages.
Old Apr 7, 2004 | 06:30 AM
  #6  
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Do I need to remove the TB to do this or can I spray cleaner in it without removing???
Old Apr 7, 2004 | 08:07 AM
  #7  
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Check the TPS readings with a scanner.
Old Apr 7, 2004 | 09:35 AM
  #8  
OBE1 95Z28's Avatar
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From: San Diego, CA
Did you clean your TB recently? I've found that my idle will hang after the TB has been cleaned. Dab a Q-Tip in oil and lube the butterfly shaft where it enters the TB housing...cured my hang.
Old Apr 7, 2004 | 09:43 AM
  #9  
Ricardo's Avatar
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It might be a PCM tuning issue. Specifically related to the IAC follower table. Just a thought...
Old Jun 7, 2004 | 06:07 PM
  #10  
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From: Cincinnati, OH
I am having the same problem. I figure it's probably the Idle Air Control Valve but I'm afraid to remove the throttle body to get to it. I bought some deep creep to clean it with, but I've heard that the gasket behind the throttle body easily rips. Is there a write up or anything?
Old Jun 7, 2004 | 07:53 PM
  #11  
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From: LSU -- Geaux Tigers!
For all those who didn't know, our TB gasket is available in Felpro from any autozone, pn 60655 for 2.29
Old Jun 7, 2004 | 10:13 PM
  #12  
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From: Miami Beach, FL
I have a very similar problem, but I have a very high idle when the engine is first started and slowly lowers to about normal or maybe a little high after running about 10 seconds or so. I have replaced TPS and IAC not having a scanner that would allow me to check actual values on these and the fact that it started right after cleaning the throttle body. I am going to try lubricating the throttle plate shaft tomorrow and I will report back. hopefully that cures it. It is really begining to **** me off.
Old Jun 7, 2004 | 10:25 PM
  #13  
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From: Detroit
I have noticed my car doing this as well, but it hasnt really been a bother for me. Would taking the elbow off and spraying the inside of the TB with cleaner do anthing for me? It really doesnt bother me enough for me to go through taking the TB off.
Old Jun 8, 2004 | 09:32 PM
  #14  
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Ok .....I lubed the throttle plate and after starting the car it made no difference, however, it did give me a chance for a second look and listen for vaccum leaks. Low and behold I found the culprit! The rubber hose that connects the metal pipe to the PCV valve was dry rotted and causing a vaccum leak. I could hear it so I pinched the hose a little and the idle came right down to where it should be. That was my story. Hopefully it will prompt some of you to look for similar problems.
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