[Biturbos4] Detecting "limp" mode?

Long, Scott G A1C USAF AFMC 88 SFS/S4W Scott.Long2 at WPAFB.AF.MIL
Fri Mar 14 06:11:23 PDT 2008

I would also suggest the coil packs.  You said the plugs are newer so
that would mean they aren't getting good spark from the packs.  Also
like mentioned look at those amplifiers on the airbox.  I don't know
what the part #'s are or the cost on those items though.

Scott G. Long

-----Original Message-----
From: biturbos4-bounces at diablo.audifans.com
[mailto:biturbos4-bounces at diablo.audifans.com] On Behalf Of Chris
Sent: Thursday, March 13, 2008 11:10 PM
To: quickaudi at gmail.com
Cc: biturbos4 at diablo.audifans.com
Subject: Re: [Biturbos4] Detecting "limp" mode?

On Thu, Mar 13, 2008 at 10:11 PM, Joel Liggins <quickaudi at gmail.com>

>  Bailey DVs have to be serviced between 15k and 25k miles.  I believe 
> you can  find the procedure on their website.  Probably not causing 
> the issue, but  couldn't hurt to try.

I'll check it out; good to know that this needs to be done.

>  If you've had the "random multiple misfires" code, then something 
> definitely  isn't right.  Those just don't randomly appear.  Is that 
> the code you had,  or was it a specific bank/cylinder?

Both, actually. I've got the "random, multiple" code as well as a
cylinder-specific code.

I can imagine how to troubleshoot the cylinder-specific misfires (swap
coil packs, etc.) Any tips on how to go hunting for the
"random-multiple" issue?

>  Random thought: have you checked the brake booster hose that plugs 
> into the  accordian hose?  Caused me to run rich and have misfires

I'll give it a look in the morning.

>  Are your oxygen sensors stock as well?  (i.e., not been replaced)

Yup; all four are still original. I'm actually surprised that at least
one hasn't gone so far off the map as to trigger a CEL by now....

>  As for a measuring block in vagcom, if you do a 3rd gear WOT run and 
> log  block 003, you might see a throttle cut condition (throttle plate

> should be  100% from 4k rpm on), or if you log block 115, you can 
> monitor boost  pressure, both requested and actual.

The specified-vs-actual boost graph is pretty much the only one I know
to try. I did a couple of 2nd-3rd gear pulls tonight and the results
didn't look too ratty. Little spikes when lifting and the occasional one
when jumping on the throttle at low RPM. It looked like the ECU pretty
much got the boost it asked for-- no major discrepancy between the
specified level and the actual.

I guess this says that, if there is an issue, it's causing the ECU to
hold back rather than a problem achieving the boost the ECU asked for...

Thanks for the suggestions.

2001.5 S4 Avant 6spd
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