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Old 08-05-2008, 04:42 PM
 
Location: in my mind
2,745 posts, read 12,851,069 times
Reputation: 1590

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I am sorry, not sure how else to describe it. When in park and the engine on, the engine "revs" and drops, revs and drops, a rhythmic idling.... once in drive it stops.

It's also overheating but I don't know if this is related.

1988 Honda Prelude, just purchased back in April. Anyone know anything about this?
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Old 08-05-2008, 05:13 PM
 
Location: Phoenix metro
20,005 posts, read 67,942,110 times
Reputation: 10048
Well, the overheating wont be related I dont think. Ill ask my brother, he had the same problem on his 1990 Si. I believe it was a quick-fix. Id guess a vacuum leak, but Im not sure if that causes rythmic idling problems or not.
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Old 08-05-2008, 06:24 PM
 
Location: Middleton, Wisconsin
4,229 posts, read 15,065,444 times
Reputation: 2279
Blown valve?
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Old 08-05-2008, 06:57 PM
 
Location: Floribama
13,483 posts, read 29,425,055 times
Reputation: 11884
Check the Idle Air Control Valve (IAC), sometimes they get clogged with carbon buildup.
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Old 08-06-2008, 04:18 AM
 
Location: Incognito
7,001 posts, read 18,161,748 times
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Quote:
Originally Posted by southernnaturelover View Post
Check the Idle Air Control Valve (IAC), sometimes they get clogged with carbon buildup.


I was going to suggest this! lol
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Old 08-06-2008, 05:35 AM
Status: "be kind." (set 22 days ago)
 
2,673 posts, read 3,880,201 times
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My son has a 96 Toyota Forerunner. When you start the car the engine 'revs' until he puts the car in gear. Is this IAC valve something a novice can check or do we need to take the car in? If so - how do you clean the carbon buildup? Thanks!
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Old 08-06-2008, 06:17 AM
 
Location: Incognito
7,001 posts, read 18,161,748 times
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If I were you I'd buy a Haynes or Chilton repair manual and do it yourself. It's not a complicated job so pretty much anybody with somewhat basic mechanical skills can do it.
I don't think it can be cleaned but I could be wrong, it is best if you just replace it with a new one.
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Old 08-06-2008, 09:04 AM
 
Location: Floribama
13,483 posts, read 29,425,055 times
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I replaced the one in my old '87 Trans Am myself, but it was easy to get to. When I removed it I couldn't believe what I saw, the 21 years worth of crud on there was amazing. I have heard of some people cleaning them with carb cleaner, but it's a cheap part so I recommend replacing it. I think I paid $23 for it at Auto Zone.
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Old 08-06-2008, 06:49 PM
 
Location: Eastern Washington
13,388 posts, read 42,701,155 times
Reputation: 11465
Do you have a Check Engine Light? Any good manual on the car will say how to read the code, or Pep Boys etc. will usually read it for you.

This probably is the IAC, generally they are not hard to change.
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Old 01-14-2013, 06:55 AM
 
Location: Detroit, MI/St. David, AZ
205 posts, read 417,315 times
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Default by request

More than likely on a prelude it is indeed an Idle Air Control valve (IAC). Could also be a vacuum leak such as from the intake gaskets or vacuum lines. This will also cause surging. And if it surges while driving at speed then a stuck EGR could be the culprit.

Last edited by observer53; 03-28-2013 at 10:39 AM..
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