Thread: Engine Oscillates RPM from 400 to 800 RPM
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Old 05-12-2008, 02:10 PM
scn101 scn101 is offline
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Default Engine Oscillates RPM from 400 to 800 RPM
'98 Jetta 2.0L ABA engine. Normally runs fine and steady at 800 RPM. However when it it hot outside (>90F) and you're idling with a high demand on the alternator (AC blower motor on high, also tried with read defroster and no AC, same effect) the engine will start to oscillate in RPM eventually going as low as 400 RPM. Turn down the electrical loads (AC blower motor on low) and it evens out to 800 RPM.

No DTC trouble codes present.

Any ideas on where to start looking? Thanks.
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