[Biturbos4] Detecting "limp" mode?

Chris Newbold chris at newbold.org
Thu Mar 13 13:10:26 PDT 2008

On Tue, Mar 11, 2008 at 1:15 AM, j y <jimnetpa at yahoo.com> wrote:

> Are you chipped? - If you are chipped there is a MUCH greater chance of your
> S4 going into limp mode from overboost than if you are not.

Stock, no chip.

> Yes, ambient temperature, fuel quality, and fuel pressure have an impact on
> boost capacity. Are you still using the stock fuel pressure regulator and
> what grade of gasoline are you using?

Stock fuel pressure regulator. I always run on 93 octane.

> Also, when was the last time you changed spark plugs? Newer plugs give your
> S4 a cleaner burn (hotter flash-point during ignition). How are your
> injectors? Maybe an injector is sticking under boost. If so, try a fuel
> injector cleaner - never hurts.

Spark plugs have about 2500 miles (brand new!); I ran a bottle of
Techron just prior to that service. Neither of these appear to have
affected the observed behavior.

2001.5 S4 Avant 6spd

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