engine idles fast then slow fast then slow, Plugs turn suty black

Asked by mamie7 Apr 17, 2008 at 03:28 PM about the 1992 Volkswagen Cabriolet

Question type: Maintenance & Repair

Enine runs fast an steady for a few seconds, then runs rough for a few seconds, back and forth.

Then after a minute or cuts off. I pull the plugs and they are sutt black, put clean plugs in and it starts right up again.

I rerplaced the Ignition coil, and fuel regulator, which works off of vacume and is attached to fuel rail.

Originally the car would run fine for much of the time, and run slugish for a few seconds and recorver, but now it does it all the time.

papa answered 16 years ago

try throtle position sensor or collent tempure sinsor.

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83,795

littlehorn answered 16 years ago

Might also try a new fuel pump or fuel filter, or perhaps injectors are bad. Sounds like too much fuel not burning off, check your timing advance as well.

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