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benhoffmann
07-09-2007, 02:32 PM
Can anyone help me..... Ive recently purchased a 1995 2ltr 8v audi cab that has a fustrating problem. most of the time the car has an irratic idle with the needle bouncing around the 1000rpm mark. When i drive the car the power is quite irratic as well, almost feels like a misfire. Unplugging the idle control valve completely cures the problem so on a recomendation from a mechanic if fitted a new one to no avail. I get the feeling mechanics re generally just scratching there heads on this one........please help!!!!!

scotty33
07-09-2007, 11:56 PM
When the isv is unplugged, does the car idle at a low engine speed? Usually a bouncing idle, is a sign that the ISV is struggling to cope. This could be because of something like a vacuum leak, which would be letting unmetered air into the engine making it run rough.
Or the throttle body could be gunged up inside, which reduces the airflow at idle,

clean up with carb cleaner.

A faulty lambda probe can make a car run rich which can affect idle. If you can identify the signal wire, (the heater wires may be white?)

connect a multimeter positive probe into the back of the signal wire connector (with the connector still connected to the loom).

with the engine running and warmed up, the negative probe needs to be earthed,

the signal in Volts should oscillate between approx 0.2 volts- 0.9volts once per second.

if it is slow or not averaging 0.5 v then the lambda probe is probably faulty

andrewaudi
18-09-2007, 10:14 AM
My break pedal goes solid straight away after the engine cuts out, and once approaching a junction where the engine cut out on it's own. I'm guessing that this is a vacuum leak?

It's idle is rough and there are one or two flat spots when it's cold.