[s-cars] Stumble at 4000 rpm

chris chambers fastscirocco_2000 at yahoo.com
Thu Oct 18 12:18:16 PDT 2007


I believe you are expereiencing the over boost fuel pump shot off.
It either has a boost leak or thinks it has a boost leak.

Potential causes:

1. torn turbo hose, usually the infamous michelin man hose between the
xover pipe and intercooler

2. bad maf

3. dirty connections on the maf or maf cable

I had the exat same problem a few years back, my cause was #3
dirty contacts on the MAF cable which I cleaned with electrical contact
cleaner. I was dumbfounded on the problem which lasted for almost a
year until I stumbled across this:


and read this paragraph:

"I have run across a couple of 20V Turbo cars which had a 2224 code
stored inside the ECU and were getting the overboost fuel pump cutout,
even though the boost was only going up to 1.0-1.2 bar. 

In the first case this would occur only when the throttle was quickly
floored, and would not happen if the throttle was gradually opened all
the way. In the first case, it ended up being a defective MAF sensor.
In the other case it was only a poor connection at the MAF sensor. 

Try using some contact cleaner on the MAF connector and terminals, and
see if the overboost problem is eliminated. "



--- audijim at comcast.net wrote:

> I have a little problem that some of you may know what it is right
> from the start. If I am cruising at 3000 rpm and then give it full
> throttle, it will fall on it's face at 4000 rpm until I lift off a
> little, then when I give it full throttle again, it will power
> through 4000 rpm again like normal. Idle/Full throttle switch bad?
> Fuel problem? It sounds like it bogged down until I lift off.... I
> have zero time to T/S this so I thought I would ask the list.
> Thanks guys,
> Jim
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list

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