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Re: High Idle 86 900T Posted by Cmyles [Email] (#1126) [Profile/Gallery] (more from Cmyles) on Sat, 25 Apr 2020 20:43:38 In Reply to: Re: High Idle 86 900T, RS [Profile/Gallery] , Sat, 25 Apr 2020 16:18:20 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Sounds like a vacuum leak to me. One method to locate the leak is to one at a time pop the vacuum lines off of the various intake manifold nipples and place a finger over the nipple quickly then see if the idle drops to normal. Do the nipples on the intake manifold and the steel nipples on the throttle body too. The big hoses like the brake booster hose or the large hose from the charcoal canister develop cracks so are likely culprits. If none of the hoses seem like they are leaking then you can look for a vacuum leak by pointing an unlit propane torch around the areas where a leak is possible. That would be primarily the intake manifold gasket joint. You can also spray carb cleaner on that joint but the propane is a more effective test. If that gasket is leaking you'll get an immediate change in the idle speed. Inspect the Idle air valve hose (the one that connects to the throttle body behind the throttle plate) for cracks or holes too.
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