Need help with idle problem

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Oct 2, 2014 | 09:25 AM

flynhi

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Le Mans Master

Joined: Aug 2000

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From: Austin TX

Need help with idle problem

My 99 has had an occasional idle/dieing problem that is getting worse.

Over the past couple of years, the engine will die at idle - sometimes when cold, sometimes when hot. Usually it clears up and idles normally after driving a couple of miles.

This has been happening more frequently and yesterday it died nine time while exiting a parking garage. Then it cleared after driving a mile or so.

The car just had a minor tune up by very experienced Corvette mechanics that did not reveal any vacuum leaks. No codes are being shown and no Check Engine Light shows. I cleaned all grounds about a year ago. The ECU has a custom tune that is otherwise great so I don't think it is a MAP problem.

Any ideas as to why this is happening will e welcome.

Thanks

Oct 2, 2014 | 09:57 AM

Corvette_Ed

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From: Phoenix area, AZ

Clean your MAF and TB, and make sure you aren't getting any unmetered air behind the MAF.

Oct 2, 2014 | 10:41 AM

flynhi

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Le Mans Master

Joined: Aug 2000

Posts: 6,273

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From: Austin TX

Thanks Ed
The 99 has been converted to Speed Density so it has no MAF.
TB appears clean. Not shiny clean but not gummy.

Oct 2, 2014 | 11:24 AM

Corvette_Ed

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From: Phoenix area, AZ

Quote:

Originally Posted by flynhi

Thanks Ed
The 99 has been converted to Speed Density so it has no MAF.
TB appears clean. Not shiny clean but not gummy.

Give it a good cleaning anyway. You'd be surprised at how much just a little bit of gunk can change things. If it persists I'd start looking at the vacuum lines.

Oct 2, 2014 | 08:18 PM

flynhi

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Le Mans Master

Joined: Aug 2000

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From: Austin TX

Hi Ed
I cleaned the throttle body as you suggested. It wasn't to bad in front of the blade but filthy behind. Idle is much better now. Thanks for the tip.

Does this mean that the inside of the intake manifold is as dirty as the backside of the throttle body? If so, how do I clean it up?

Thanks again.

Oct 3, 2014 | 08:05 AM

Corvette_Ed

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Quote:

Originally Posted by flynhi

I'm glad that helped. I don't know about the intake; someone with more knowledge than I have will have to answer that question for you. I've never taken my intake off.

Oct 3, 2014 | 12:35 PM

flynhi

Thread Starter

Le Mans Master

Joined: Aug 2000

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From: Austin TX

Would Seafoam clean the inside of the intake manifold?

Oct 3, 2014 | 01:49 PM

Corvette_Ed

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From: Phoenix area, AZ

That's a very good question. Hopefully one of the more knowledgeable members can answer it for us, because I really don't know. I've never seen an intake off of the engine so I don't know how things flow inside of one.