C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

rough idle

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Old Sep 25, 2002 | 12:19 AM
  #1  
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From: Denton Tx.
Default rough idle

does anyone elses car have a rough idle when you first crank it in the morning. I know its not the timing i cant figure out what it is :mad


[Modified by spineshank, 11:19 PM 9/24/2002]
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Old Sep 25, 2002 | 12:22 AM
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Default Re: rough idle (spineshank)

seems to be common here lately

Clean the throttle body and IAC valve (order a Helm Manual from helminc.com)
If that doesnt fix, try a full tune-up.
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Old Sep 25, 2002 | 04:44 AM
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Default Re: rough idle (spineshank)

I've read about some cold-start system problems. You might want to check out the cold-start stuff (I don't have the details handy).
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Old Sep 25, 2002 | 08:57 AM
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Default Re: rough idle (spineshank)

Check your "9th" injector
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Old Sep 25, 2002 | 06:44 PM
  #5  
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Default Re: rough idle (Quik86)

Adding to your list of what to check, Engine Coolant Temp (ECT) sensors can cause poor idle during cold starts. If you have access to a scanner, compare ambient air temp to scanner readout for the ECT. They should be within a couple of degrees. Does the car run better when you step on the gas and try to sustain say 1500 RPM?

Hope your car is fixed soon.

dlmeyers 90 coupe zf6 3 speed shocks
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Old Sep 25, 2002 | 10:38 PM
  #6  
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From: Denton Tx.
Default Re: rough idle (dlmeyers)

yeah it gets better when it gets above 900rpm or after labout 5 minutes of just running and i know its not cause i need a tune up cause i just did one 3 weeks ago
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Old Sep 26, 2002 | 12:37 AM
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Default Re: rough idle (spineshank)

I'm having the same problem. Only in the morning, and it goes away after a couple of minutes.

I took a look at the throttle body and it looks like it's been cleaned recently. Make sure the butterflies are opening and closing properly. Manually open it to WOT and clean behind the butterflies themselves. If it's like mine, there's going to be a lot of nasty buildup behind there. I can't find any throttle body cleaner around here for some reason, but I assume once I find some I can spray it in there to clean things up a bit. The book I have says to use it somewhat sparingly though, because the liquid itself and the junk it washes off has to go somewhere.

I'd appreciate it if you'd let this thread know if you get the problem fixed. Likewise, I'll let you know if it fixes mine. I suppose if it doesn't, I'll check my 9th injector next.
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Old Sep 26, 2002 | 09:28 PM
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From: Denton Tx.
Default Re: rough idle (Tourney3p0)

that didn't help i just did that today and i still got the same results but one thing i did notice is that the idle smooths out sooner now
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