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Re: V8 surge problems

Majewskier@aol.com wrote:
>
> My '90 V8 "surges",  for lack of a more exact term.  At part throttle. ie.
> when cruising at a steady highway speed, I can definitely notice a somewhat
> cyclic increase/decrease  in engine output. These cycles are about a second
> long...+-+-+-+-+-.   The effect is subtle enough that it doesn't show up on
> the tach or speedo, but wife and I have noticed it by seat of the pants. 
> 
> Since writing the above, I am wondering if I am experiencing a bad Ox sensor
> and if I am noticing the lambda? rich/lean feedback loop?  The car only has
> thirty some thousand miles, but it is over five years old. It has had all
> dealer related service performed before I purchased it, including the 30K
> tune.  Could that expensive little Bosch piece be failing already?
> 
> Also, I am also paranoid about the Seattle-area (m)ethanol gas from Nov to
> Feb.  Especially because of this, I plan on changing the fuel filter soon,
> since is not part of any dealer service, but I think these two things are
> coincidental.

Today I took my 90 V8 to the dealer for a repair, it is also due for 
its 90K service so I asked about the Ox sensor because I have 
noticed the same exact symptoms that you have described.  They 
explained that a bad Ox sensor would cause surging only at idle.  
Therefore, this could not be the cause of the problem.  I tend to 
believe them, because have you ever heard of a dealer *not* wanting 
to perform a service!  They explained that this problem is inherent 
to the V8 and something that they have narrowed down to a 
transmission software problem.  Since my car has the original 
transmission software, possibly that could help?  Eliot might shed 
some light on that.  Also, if someone with a 5 speed V8 has 
experience this then the transmission software theory could be 
eliminated.  Oh well, it is only a minor distraction during driving.  
Now about the seatbelt retractor...... that's another story!

Randall C. Markarian

1990 V8 Quattro