[s-cars] Saga continues: Miss not from bad WGFV - Could it be the MAF?

[Walsh, Edward]

I realize this thread is getting old, but WTF,  I need da boost.  The WGFV
is OK, so here is where we, err , I stand:

95 S6 with 83k

- Plug connectors all have 5K ohm resistance
- Plugs are good
- ECU is good
- WGFV is good
- Coil pack is good
- Idle is smooth
- New O2 Sensor
- Turbo is quiet
- Waste Gate is not torn, slides smoothly up and down with no play
- Power is smooth until about 1 bar
- Miss is subtle, but prevents boost from hitting 22-23 (MTM 1+) in all but
gears, boost fluctuates from 17-20.5 in 5th gear
- Miss is worst when accelerating hard on the Hway, after coasting in heavy
vacuum for a while (like slowing for traffic on a 2 lane road, downshifting
from 5th to 4th, then overtaking on the left - big stumbles/brown pants)
- Miss is most apparent when engine is COOL
- Motor will over boost to 28+ PSI if floored at low RPM (<2,500) in 3/4/5
gear.  When boost is that high, the motor makes a different, very rapid
"thumping" noise.  ECU will sometimes bring boost down to safe levels, but
sometimes it won't, and only my right foot prevents a grenade.

Everything in the ignition system checks out.  Boost plumbing seems fine.
Could the MAF be throwing bad values to the ECU under high boost? (I use
paper filters)  Is there a test procedure for the MAF?  Could a bad MAF
cause the mentioned symptoms?

Thanks for any/all advice,

Ed


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