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Bizarre Idle Posted by Justin VanAbrahams [Email] ![]() ![]() |
What the heck is going on here?
Yesterday, unprovoked, my '86 900S started idling at 1600rpm. The only change was spark plugs, from Beru Silverstones to NGK BCP6ES. The change was for emissions... Anyway, cold idle is rock-solid and perfect at 900rpm. After warming up, idle creeps up to 1600rpm and won't go back.
There are no vacuum leaks, everything is well in spec. I switched the AIC out with one from my '88 9kt so I've ruled out some sort of spontaneous component failure. The AMM is a couple weeks old (rebuilt) as is the O2 sensor. I can't think of anything else involved here that could cause problems.
Unplugging the AIC with the car running does not change the idle, leading me to believe it's just open. Unplugging the NTC sensor with the car idling at 900rpm causes it to immediately jump up to 1600rpm - strange coincidence or failed NTC? I've not yet tried unplugging it while the car is idling high to see if it jumps higher.
Any ideas? The car is a little overdue for a smog check and I gotta fix it this weekend! I'm running out of ideas...
-Justin
posted by 66.123.9...
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