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ZUKIWORLD Discussion Forum => Technical Discussion - Beginner / Repair => Topic started by: 91 ragtop on July 08, 2025, 07:39:34 PM

Title: What causes high idle besides vacuum leaks ?
Post by: 91 ragtop on July 08, 2025, 07:39:34 PM

My 91 8 valve has a very high idle (around 2500 rpms) and I can't find any leaks or cracked hoses anywhere. Is there some other component that I should be looking at for a cure ?

Ken.............

Title: Re: What causes high idle besides vacuum leaks ?
Post by: fordem on July 09, 2025, 06:35:28 AM

On a fuel injected engine, high idle is caused by excessive air flow - the trick is to find where the air is getting in.  It can be the throttle plate open more than it should be, or air leaking into the intake, which is your so called "vacuum leak" - PCV valve & hose, brake booster, literally anything connecting on the manifold side of the throttle plate.  There's also I believe a throttle opener on those motors that holds the throttle plate open for the first 5 seconds or so after startup.

Title: Re: What causes high idle besides vacuum leaks ?
Post by: 91 ragtop on July 16, 2025, 08:27:54 PM

Thanks for the info. I'll see what I can figure out.


Ken..........