[V8] Intermittent High Idle Speed

[radek@istar.ca]

Do you live in the rust belt?  It could be a sticking accelerator shaft.  It sits in two
bearings 
that can get rusty.  With the engine off, move the throttle and then release, 
listening for a "click" from the TPS.  Does the shaft return to the "click" position 
quickly and easily?  If not, you probably have to replace one of the bearings, a $20 item.
 
I posted a procedure some time ago and should still have the part number 
if you need it.
Good luck.

Radek
91 V8Q 5-sp.
88 90Q
 
> Message: 5
> Date: Wed, 2 Nov 2005 20:27:56 -0600
> From: "Carol, Dave, and Zach Weiss" <cdzweiss at charter.net>
> Subject: [V8] Intermittent High Idle Speed
> To: "V8 List" <v8 at audifans.com>
> Message-ID: <000501c5e01e$33ef7920$b302a8c0 at default>
> Content-Type: text/plain;	charset="us-ascii"
> 
> For those that love a puzzle--  ;)
> 
>  
> 
> When coming to a stop, clutch in, engine speed occasionally catches
> somewhere between 2000 and 3200 rpm (usually closer to the low end).  "Idle"
> is rock solid at those times, just high.  Revving the engine has no
> effect-engine returns to whatever speed it's seemingly trying to idle at (at
> the time).  Turning the car off returns the idle to normal.  The engine runs
> well other than this-plenty of power, no misses, etc.
> 
>  
> 
> I let my mechanic look at it, and he at first thought it was the accelerator
> cable.  I didn't see how that would explain the off/on reset, and sure
> enough, although there was a definite hitch in the cable, the problem is
> still there after replacement.
> 
>  
> 
> Now he says it's a combination of engine speed sensor (he got an
> intermittent code, although I don't know which one) and a slow ISV.
> 
>  
> 
> Seems like speed sensor or slow ISV would cause idle to be erratic.
> Sticking ISV or throttle plate should cause code 2231 idle adaptation out of
> range.  Could this be the idle switch (but if so, wouldn't it cause a 2121)?
> If not, is it likely an ECU problem?
> 
>  
> 
> Recently rebuilt top end eliminated excessive oil consumption.  Ned's chip
> has been installed for years.  Only other problem has been an occasional
> miss on lift throttle that disappeared after a new O2 sensor, long ago.
> 
>  
> 
> Dave Weiss
> 
> '91 5-speed