[s-cars] Inconsistent Boost / Power Loss

[Sean Douglas]

I'm trying to diagnose a boost and/or power loss problem. I've been
running the MTM stage 1 software with 3 bar pressure sensor for about 6
weeks now. Before I did the MTM, I replaced all spark plugs and
connectors and made sure the spark plugs were torqued.

In the last 2 days, I've noticed a drop in performance, but only
sometimes. When it occurs, the power is down and the kick in the pants
is gone. I haven't determined a definitive trend (hot/cold), but when
cold, it seems fine and when hot/warm the problem sometimes occurs. I
don't have a boost gauge (its on the list), so I can't compare boost
levels.

Today I replaced the stock BPV (710A) with a 710N thinking this may be
the problem, but it didn't help. The boost hoses (turbo to x-over and
x-over to intercooler) are new (stock). The intercooler to intake
manifold hose is original, but looks good. I haven't fully inspected the
hoses yet for any tears or leaks. I checked the hose connection at the
ECU and its tight (clamped). The moisture trap is next to the ECU and
the connections are tight.

My hunch is a faulty power output stage, ignition coil or knock sensor.
I haven't pulled any codes yet, but I plan to use a VAG 1552 to do this.

Any words of wisdom would be appreciated.

Thanks,

Sean

Sean Douglas
1997 Audi S6
1990 Audi 90Q20V
Surrey, BC
Canada