[s-cars] Go. No go. And; go.

[chris chambers]

I'd also recommend checking to see if the fuel pump's inlet is plugged.
I seem to recall Posto having a similiar issue and  he discovered the
inlet tube on his fuel pump was partially plugged.

Changing the pump isn't hard, well now that I know how to release it anyway.

Billy boy, if you decide to swap pumps give me a call and I'll tell 
you about my swap.

HTH
Chris


--- On Thu, 4/9/09, Brett Dikeman <brett.dikeman at gmail.com> wrote:

> From: Brett Dikeman <brett.dikeman at gmail.com>
> Subject: Re: [s-cars] Go. No go. And; go.
> To: "Bill Mahoney" <wmahoney at disk.com>
> Cc: s-car-list at audifans.com
> Date: Thursday, April 9, 2009, 9:17 AM
> On Wed, Apr 8, 2009 at 11:07 AM, Bill Mahoney
> <wmahoney at disk.com> wrote:
> > Maybe O2 sensor?
> 
> Motronic is open-loop during startup and for a few minutes
> until the
> O2 sensor warms up.  Also, O2 sensors rarely go
> "bad"; their response
> time just increases with contamination.  If the sensor was
> disconnected or had a bad connection, you would see a check
> engine
> light or have a fault code.
> 
> Aside from major fuel/ignition problems (ie coilpack
> failure, fuel
> pump relay/pump failure, pressure regulator, etc)- what
> would affect
> startup mixture and idle speed would be the ECU coolant
> temp sensor,
> MAF sensor, idle stabilization valve, and...drumroll
> please...intake
> system leak.  The ISV obviously wouldn't affect
> acceleration, but the
> ECU temp sensor and MAF sensor sure would...and sudden
> stumbling under
> acceleration.  Because of the ease of checking, it is worth
> it to
> check the vacuum line to the FPR; if it fails or becomes
> disconnected,
> the engine will run very rich at idle.  You'll also
> eventually get a
> CEL on this, because the ECU will try to compensate for the
> rich
> running.
> 
> Murphy's law is that it will be the pump if I say this,
> but- there are
> a number of other things you need to be checking out before
> you commit
> to a major job like replacing the fuel pump. At the very
> least, pull
> codes using VAG-COM (blink codes don't cover
> intermittent fault codes)
> *AND* check the first memory block to see if values are
> within norms
> (but note that there are very specific conditions for the
> ranges given
> in the Bentley- mostly around running time, coolant temp,
> battery
> voltage.)
> 
> Start with the easiest stuff to test, even if the
> likelyhood is low.
> If you need to do a boost pressure test, raid the
> tupperware drawer; 1
> cup rubbermaid containers (the kind with the tan covers)
> are a
> near-perfect fit for the hose off the MAF.  Just be REAL
> careful not
> to over-pressurize the system more than .5 bar above normal
> boost
> levels.
> 
> Really, your first stop should be here:
> http://www.sjmautotechnik.com/trouble_shooting/20vboost.html
> 
> Brett
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