2nd Generation Specific 1986-1992 Discussion

Inconsistant Idle

Old 03-01-2005, 06:37 PM
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when the car is cold and starts up after a long period of rest, it'll idle great - 900 rpms. after it warms up the idle will jump to about 1200 rpms or slightly higher or lower - not really a predictable number. i can however, lower the idle to maybe 950 rpms by keeping my foot on the brake and letting the clutch pedal out so it forces itself back down. but when i drive again and let it idle...same thing.

my only thought right now is a bad bac valve or i need to reset the tps
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Old 03-01-2005, 08:50 PM
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reset the tps, have a look at the thermowax too. mine does the same thing cause my radiator is so gigantic that it cools off enough to pop the thermowax back on occasionally
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Old 03-01-2005, 10:35 PM
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the thermomax might be the cause...although i have had my koyo for about 18 months now and its the first time its happened

thermowax is near the TB correct?
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Old 03-01-2005, 10:59 PM
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I have had those problems on my cars always. It comes and goes. Normally it is striking the right balance between the TPS and the hard idle screw on the TB.

Turn the hard idle as low as it will go almost and then adjust the TPS to ensure it has 1 volt at idle. You might have to continue the process until you get the right balance. My car used to do that and I did not have the thermowax or anything on it at all.
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Old 03-02-2005, 10:57 AM
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Make certain TPS is good and set properly, and check the inner seal on the BAC for any air leakage.
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