idle surge

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idle surge

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Corvette Forum >> Corvette Models >> Corvette C4 Forum >> idle surge

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idle surge - 9/11/2008 10:11:56 AM

scooterman

Posts: 63
Joined: 4/16/2007
Status: offline

Please help! My 94 has developed a surge at idle after warmup. the tach will jump iraticaly, and idle up for a second, then normal and back and forth like that. I replaced the iac but to no avail. I have a slight oil leak from the intake ( i think) but no vaccum leaks that i can find. any ideas?

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black 94

Post #: 1

RE: idle surge - 9/11/2008 11:28:25 AM

LeesVette

Posts: 576
Joined: 3/24/2006
Status: offline

I know you say you don''t have any vacuum leaks but thats sure what it sounds like.

(in reply to scooterman)

Post #: 2

RE: idle surge - 9/11/2008 2:35:49 PM

firedragon78

Posts: 13
Joined: 9/2/2008
Status: offline

Check your fuel pressure.Could be a bad fuel pressure regulator or pump.Just a thought!

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T.R. LB,N.J.

(in reply to LeesVette)

Post #: 3

RE: idle surge - 9/12/2008 12:40:12 PM

mech259

Posts: 1760
Joined: 1/22/2006
From: Lumberton, Texas
Status: offline

Injector orings leaking vacuum @ intake will cause that problem to. Try spraying carb spray arounf intake gaskets and injector orings where the injectors go into the intake. Other than that, would have to see scan tool data to properly diagnose your problem. Have you checked codes yet?

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L.B.
ASE Master Certified
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1986 C4
1969 RS Z28 Camaro
1970 Chevelle SS 396 (under construction)

(in reply to scooterman)

Post #: 4

RE: idle surge - 9/12/2008 6:21:06 PM

scooterman

Posts: 63
Joined: 4/16/2007
Status: offline

won''t set a code. sprayed carb cleaner around injectors earlier- and intake- no effect at all. I also replaced ect (figured it couldn''t hurt) It did this a couple of times a year ago and went away as fast as it showed up. now it''s constant

(in reply to mech259)

Post #: 5

RE: idle surge - 9/13/2008 1:14:37 PM

cwb

Posts: 1508
Joined: 5/13/2007
From: eastern NC
Status: offline

quote:

ORIGINAL: scooterman

won''''''''''''''''''''''''''''''''t set a code. sprayed carb cleaner around injectors earlier- and intake- no effect at all. I also replaced ect (figured it couldn''''''''''''''''''''''''''''''''t hurt) It did this a couple of times a year ago and went away as fast as it showed up. now it''''''''''''''''''''''''''''''''s constant

How do you know it didn''t have an effect?

Did you put a brick on the gas pedal? Block the throttle body arm?

What did you do, before you sprayed the carb cleaner, to increase the idle to a STEADY idle, WHICH YOU HAVE TO DO, so that you know when the carb cleaner has hit the leak that you have???

I suggest you do it again, and spray JUST A LITTLE AT A TIME, and wait for the spray to dissipate, before hitting another TINY spot. ...

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Don''t know nuthin''; ain''t never got paid for wrenchin''...
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Post #: 6

RE: idle surge - 9/13/2008 8:27:28 PM

JoeVetteman

Posts: 260
Joined: 11/18/2006
Status: offline

Maybe you don''t have correct fuel pressure?? Correct injector pulse?? I tell ya,sometimes when our cars have even a slight problem it seems it will either solve itself or a miraculous intervention may be in order,LOL!!! Good luck,and tell us what happens,ok???? Joe

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Post #: 7

RE: idle surge - 9/14/2008 9:55:57 AM

scooterman

Posts: 63
Joined: 4/16/2007
Status: offline

will do!! i am going to look for a leak again, and test fuel pressure. i''ll post the results as they happen

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black 94

(in reply to JoeVetteman)

Post #: 8