[V8] engine surging at idle, jerk when decelerating - TPS troubleshooting

Tue Feb 10 20:13:05 EST 2004

Actually it really isn't that hard to adjust.  Mechanically all you need
to adjust is where the shift linkage is mounted to the transmission.  If
you jack the car up and look for the accordion looking boot that
protects the shift linkage, there should be two allen bolts attaching it
to the mounting plate on the end of the accordion boot that is in the
middle of the linkage.  If you loosen the allens you should be able to
seat the shifter correctly.  Just a tip, there should already be
circular marks from where the allens were for 6+ years.  Try to make
sure you adjust it according to those markings.

Shawn Head

-----Original Message-----
From: v8-bounces at audifans.com [mailto:v8-bounces at audifans.com] On Behalf
Of Jeremy Ward
Sent: Tuesday, February 10, 2004 2:20 PM
To: kyle leatherwood; v8 at audifans.com
Subject: RE: [V8] engine surging at idle,jerk when decelerating - TPS
troubleshooting

The park/reverse is a fairly common one.  It causes a starter motor lock
out, and won't start until you jiggle it into park.  Mine seems to only
have this problem when my wife wants to borrow it. :-)

I think you are right about the transmission shop not quite getting the
multifunction switch lined up exactly...  There is probably a procedure
for adjustment found in the manual, which can be purchased on CD from
www.rb.com 

Will the transmission shop honor fixing it under warranty for a new
owner?  Will the PO be willing to take it back in under his warranty for
you?  I am guessing this switch is located on the top of the
transmission and is a bear to get to...

Good luck,

- Jeremy

-----Original Message-----
From: kyle leatherwood [mailto:kyle_leatherwood at hotmail.com] 
Sent: Tuesday, February 10, 2004 11:08 AM
To: Jeremy Ward; v8 at audifans.com
Subject: RE: [V8] engine surging at idle, jerk when decelerating - TPS
troubleshooting

Jeremy,

My tranny has not gone into limp mode without lighting up all of the
lights 
on the dash, however I have noticed that the shift lever seems to be out
of 
adjustment because sometimes when I put the selector into park it
sometimes 
shows it as being in reverse.  If I cut it off with it showing it is in 
reverse, the tranny is in limp mode the next time I start it up.  Also, 
sometimes if I am in drive the lights show me as being in 3rd.  The
previous 
owner had the tranny pulled because the flywheel ring gear got chewed
due to 
the infamous fuel pressure regulator problem and I do not believe they
got 
the selector lever adjusted properly.  What to you think? I'll take a
look 
at the throttle linkage tonight.  Thanks for the help.

Kyle

90 V8 Quattro
90 Audi 80
85 Jaguar XJS
71 MG Midget
69 MGB

>From: "Jeremy Ward" <jward at mti-interactive.com>
>To: "kyle leatherwood" <kyle_leatherwood at hotmail.com>,<v8 at audifans.com>
>Subject: RE: [V8] engine surging at idle, jerk when decelerating - TPS 
>troubleshooting
>Date: Tue, 10 Feb 2004 10:25:49 -0800
>
>Sounds like the Throttle Position Sensor to me, specifically the Idle
>Switch.  The computer didn't realize you took your foot off the gas and
>didn't compensate; this made for a rough transition from lots of fuel
to
>no fuel.  Did your transmission go into limp mode (stuck in 3rd gear)
>with out lighting up all of your PRND321 lights?  This is what happened
>to me...
>
>The TPS is located on the front of the engine and attaches to the post
>that comes out the front to the throttle body.  There are 2 Phillips
>screws that hold the TPS through the slotted mounting brackets to the
>throttle body housing.  These are adjustable (to a certain extent) so
>you might get lucky with loosening these screws, rotating the TPS to a
>better position, and re-tightening the screws.  You will get a 'click'
>sound then the idle switch makes contact at the 'foot off the
>accelerator' position.  There is a little lever on the front of the
>throttle body that you can use to open and close the butterfly valves,
>thus simulating a foot on the gas pedal.  In my case, no matter how far
>over I had the TPS adjusted, I didn't get the 'click' unless I pressed
>the leaver down to the 'even more closed' position.
>
>2 things were attributing to my problem.  1) The transmission shop
>buggered up (bent) the throttle linkage (you have to take the air cover
>and air box off to see it) that goes to the cruise control vacuum
>diaphragm. 2) The PO had installed a K&N air filter and either
>under/over oiled the thing...  My TB butterfly valves were so filthy
>with oil and dirt, that the valves wouldn't close all the way on their
>own.  I removed the TB (6 Allen bolts) and cleaned it real well with TB
>cleaner.
>
>You can verify your problem by pulling the engine codes.  You can use a
>laptop, Palm Pilot, or a current-limited LED.  Instructions can be
found
>for the latter here (very easy to do):
>http://www.sjmautotechnik.com/ecufv8.html
>
>After re-reading your post, I have my money on bent linkage, which
would
>not only cause the idle switch problem, but also a high idle.  Oh yeah,
>and if you need it, a TPS can be found at AutoZone for $67 (or twice as
>much from the stealership); they will tell you it is a 'Wells' part,
but
>mine was a Bosch OEM in a Wells bag...
>
>Welcome to the brotherhood of penniless frustrated V8 nuts.  ;-)
>
>Regards,
>
>- Jeremy
>
>
>-----Original Message-----
>From: kyle leatherwood [mailto:kyle_leatherwood at hotmail.com]
>Sent: Tuesday, February 10, 2004 3:35 AM
>To: v8 at audifans.com
>Subject: [V8] engine surging at idle, jerk when decellerating
>
>Hello,
>
>Kyle Leathewood here.  I just purchased a 1990 V8 Quattro and it does a
>surging at idle, as well as idles high.  The surging is as if you are
>pressing the gas pedal a considerable bit (1000 RPM to 1500 RPM) and it
>sometimes does it when you are slowing down after driving.  Along with
>this
>surging, it does a sort of jerk when you let up off of the gas pedal,
>almost
>as if you are lightly tapping the brake each time.  It gets quite
>annoying.
>
>I am told the surging and high idle could be due to a recall on the
>throttle
>linkage bushing not allowing the throttle to go back to full stop,
>however
>the jerking has got me stumped.  Any suggestions would be greatly
>appreciated.
>
>Thanks,
>
>Kyle
>
>90 V8 Quattro
>90 Audi 80
>85 Jaguar XJS
>71 MG Midget
>69 MGB
>
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