Rising and falling throttle at idle.

[John Sherrow]

I would suspect the ISV not a vacuum leak.

Engine vacuum is pulling air past the ISV rasing the idle till fuel cutoff
that's why the idle cycles.

I suppose you're using the heat also now that fall is here. The climate
control boosts the idle to compensate for compressor load. You might be able
to back the idle screw down aways to stop the problem. But likely the ISV is
shot.

----- Original Message ----- 
From: "Robert Beatty" <beattyr2003 at earthlink.net>
To: <quattro at audifans.com>
Sent: Tuesday, October 12, 2004 7:04 PM
Subject: Rising and falling throttle at idle.


> 89 200TQ thats suddenly started acting slightly odd.  At idle I get a fast
> idle of about 1400 rpm and then once the motor is warmed up, it cycles
> between 1200 and 1600 rpm, cycling about every 2 seconds or so.  I believe
> its a vacuum leak, but I haven't been able to find it yet.  I've checked
all
> the connections, looked over the lines and havent seen anything obvious.
>
> Anyone have any experience with this particular leak and remember where it
> was?  If not, how about some ideas on how to find a vacuum leak thats
being
> difficult without pulling every single line off the motor and inspecting
it?
>
> Thanks,
>
> Rob
>
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