1988 Honda Prelude Idle speed

HOCKEYDUDE515

MEMBER
1988 HONDA PRELUDE
4 CYL
FWD
MANUAL
13,000 MILES

I have a question for you about the idle speed of my car. It actually has to do with when u start it. When started, it runs hits 2,000 rpms and keeps rising until it is at an upwards of 3,200 or more and then in about 5 min. Or less it will slowly decrease and then go to a very low idle so it sounds as if it will quit. A good friend and car fanatic told me that I should check out the vacuum with a meter to check if there is a leak because that can cause the problem. I was wondering what you input on this subject was if he was correct and what u believe the problem could be.

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1 Reply

KHLOW2008

MECHANIC
41,814 POSTS

Hi hockeydude515,

Your friend is correct up to a certain extent.

The cold start valve (Fast Idle Valve) is faulty/incorrectly adjusted/opened too much resulting in the extremely high rpm, 3,200. (Vacumn leakage)

When the engine seems like stalling after warming up, insufficient amount of air is getting into the intake manifold. This is due to clogging of air passages.

I would recommend checking EACV, throttle body and their coolant hoses for clogging.

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