89 929 Surging @ idle

06-18-2007, 11:26 PM
After about 4 mins of operation the engine starts to surge between 1800 - 2200 RPM. It does not ever go back to it's normal idle of 800 RPM. When I remove one of the hoses that runs from the left hand valve cover to the intake plenum the surging stops, but the idle is still at 2000. Any ideas?

04-30-2008, 08:15 PM
Check the idle control valve try to clean it good before replacing.

hellah fresh
10-23-2008, 09:03 AM
I have the same problem on my 89 929. When i first start the car it idles really high. After about a minute or 2 the idle starts to serge going up and down non stop. I went thru 3 idle valves. Any other solutions?

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