engine speed and AT

[Ed Kellock]

Sounds to me like, in relation to activating a window switch, your
alternator is bogging the engine because it's compensating for a heavy load.
It may feel like a vibration if you have worn motor mounts.  Normally, one
window shouldn't produce a load enough to do this.  Does the window move as
it should or is it slow?  If you do more than one window at a time, what
happens to engine idle?  

I often roll up all four windows at a time manually with the switches using
both hands.  When I do this there is a very obvious reduction in idle speed.
Your issue sounds somewhat similar.

Ed

> -----Original Message-----
> From: quattro-bounces at audifans.com 
> [mailto:quattro-bounces at audifans.com] On Behalf Of Kent McLean
> Sent: Sunday, February 15, 2009 6:34 AM
> To: quattro at audifans.com
> Subject: Re: engine speed and AT
> 
> 
> Snoopy wrote:
> > Hi. Does my car have any kind of engine speed increase/regulation, 
> > when the car is not moving, transmission is in "D", and brakes are 
> > applied?
> > 
> > Recently I noticed a very slight engine "shake" under conditions 
> > mentioned above. It can be increased for example by pushing window 
> > button, then engine visibly drops ~100rpm and starts 
> shaking like it 
> > was working on 4 cylinders. Normal idle (transmission in P or N) is 
> > fine.
> 
> Not that I'm aware of. The engine does have various sensors, 
> to adjust the idle. But "normally" the idle should be steady.
> 
> My guess -- an oxygen sensor. If it goes bad, the idle will 
> "hunt", slowly rising and lowering, not quite steady.  If you 
> hit the window switch, the electrical load of the window 
> motor puts a load on the alternator, which slows the engine 
> since the O2 sensor is dying. Again, just a guess.
> 
> -- 
> Kent McLean
> '99 A4 Avant, V6 Tiptronic
> '91 200 TQA #3, with mods
> gone: '91 200 TQA x2, '94 100 S Avant, '89 200 TQ
> 
> _______________________________________________
> quattro mailing list
> quattro at audifans.com http://www.audifans.com/mailman/listinfo/quattro
> ---
> Watch this space for ads :)
> No virus found in this incoming message.
> Checked by AVG - www.avg.com 
> Version: 8.0.237 / Virus Database: 270.10.23/1953 - Release 
> Date: 02/14/09 18:01:00
>