[Biturbos4] Detecting "limp" mode?

Joel Liggins quickaudi at gmail.com
Thu Mar 13 19:11:57 PDT 2008


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 heartily suggest pressure testing your system and also pressure testing
the wastegate lines.  If you can find someone who has heard a boost leak
before, especially from the wastegate lines, that'll help a lot.

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?

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

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

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.
Plots helps on the above.


-----Original Message-----

On Wed, Mar 12, 2008 at 8:53 PM, Joel Liggins <quickaudi at gmail.com> wrote:

>  Last time you cleaned/oiled your Bailey DVs?

Uh, never. They've been in there about 18 months or so, maybe 15,000 miles
on them. What's the recommended maintence interval and procedure for these?

>  Have you pressure tested for boost leaks (Samco doesn't mean you 
> haven't  blown a hose off)

I have not done an explicit pressure test, but the fact that I observed this
behavior prior to the installation of all the Samco hoses and that there was
no change following the install pretty much says that there isn't a leak
from one of those hoses. (The host install was done about 2500 miles back.)

Now of course there could be a leak somewhere else, in some vaccum lines or
other control plumbing...

>  What maintenance have you performed in the last 60k miles? (spark 
> plugs, air  filter, clean throttle body, fuel injector cleaner, etc.)

Spark plugs, timing belt, water pump, intake hoses, air filter, etc. (the
"full monty") about 2500 miles ago. The boost issues predated the service
and appear to have been unaffected by the service. I ran a bottle of Techron
prior to the service.

>  Limp mode doesn't necessarily mean you'll get a CEL.

Good to know. Is there a particular measuring block in VAG-COM which will
indicate whether the ECU is in "limp" mode?

>  Have you found any codes via VAGCOM?

Just a couple of mis-fires.

>  How many miles on your car?  Some seem to have had wastegate line 
> issues...

About 83,000.

>  Are your EGTs stock?

Stock and still original.

2001.5 S4 Avant 6spd

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