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From digest.v4.n790 Mon Jul 1 07:11:27 1996
From: Looi Cheng Hock <lchock at>
Date: Mon, 01 Jul 1996 17:20:57 MYT
Subject: <MISC> Re: Car stutters when transitioning between on/off throttle: FIXED

This Sun, 30 Jun 96 08:45:48 EDT (David Hoerl) wrote:

>I had posted a while ago about the car shaking when driving on local roads,
>particularly when I had to off/on throttle the car: speeds in the 25-35 MPH
>range. We'll, I finally fixed it, and my "fix" may apply to others.

(snipped... re: previous thread)...

>Bottom line: if you have this problem at all, or an older car, look
>at that throttle assembly to see if some IDIOT has played with this adjustment
>that under normal maintenance would NEVER be touched.

Bingo! Like a stalking eagle... gotcha! I mean your most invaluable piece of information. <grin> I immediately went off to check...
Thanks, David...
In my case, I had just about replaced the whole damn lot of sensors, idle control valve, idle position switch... and many other items that really needed replacement. It has be more than a year since! Sure 'nuff, the position of the throttle stop was out by almost an eighth of an inch - reading off from the edge of the plate. Luckily, like you... the dab of yellow paint's still there. The rest is history.
Particular to my case, probably a mechanic, along the line, whilst trying to solve a case of *excessive* air into the system - corrected that by *closing* the throttle plate (butterfly). When I took over possession of the car, I did some checking/servicing and found that the rubber-bellow duct between the air-flow sensor and the throttle plate was way beyond further use, leaking badly around the bottom section - hardly visible from the top.
With that replaced, the fuel-air mixture was upset - being too rich and, unknowingly... adjusted the idle-air bypass valve. That has a very narrow range of adjustment, unable to maintain a smooth transition between idle and take-off all these while. Many thanks again. Your piece of info should go into the FAQ list :)

>David Hoerl
>84 633CSi
>78 320i

  • -- chL00I via DeskTopPC West Malaysia. '84 E23 728i '71 Opel Manta SR
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