[Diy_efi] Out of the blue high idle

[TomQ]

I unplugged the connector of the IAC (the new one) and it still revs to
high. Does the TBI only adjust the idle through the IAC?

-TomQ

-----Original Message-----
From: TomQ [mailto:zippy at tomquinn.com]
Sent: Wednesday, July 02, 2003 6:31 PM
To: 'List for general do-it-yourself EFI talk'
Subject: RE: [Diy_efi] Out of the blue high idle


Ok I replaced the TPS and the IAC and it didn't fix the problem. What was
interesting is when I drove it to the store to pick up the parts the idle
seems to have fixed itself after the motor warmed up a bit (say 15 minutes
of driving). If I let it cool all the way down (say 2 hours) the problem
comes back. More ideas? Any parameters I should check with ALDL?

-TomQ


When the TPS fails, the new carbon track becomes the "auto zero" point. You
then end up with a high idle when the throttle is at rest. Replace your TPS.

Lyndon

> Hi all,
>
> I have been running a GM '747 TBI system on my motor (4.2L I6) now for
about
> two years and it has worked great with no problems at all. All of a sudden
a
> few days ago when I started it up it started to idle way up at around 2500
> instead of 800. First thing I thought was maybe there is a leak in the
> intake somewhere. I looked it over the intake trac but didn't see anything
> with holes or cracks in it. I did replace two intake caps that looked
> questionable but that did not fix the problem. I am now getting an error
21,
> throttle position sensor too high. I am looking for advice on how I should
> start to tackle this problem.
>
> TomQ



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