S4 high speed miss

["Frank Amoroso" <FAmoroso@svbank.com>]

Calling all q heads!

Hello all,

I am having a problem with a high speed, high load, high boost miss / buck 
that my S4 experiences on occasion.

It is a '93 S4 with 65,000 miles and a Hoppen Stage III RS2 kit. It is very 
strong and runs very  well for the most part, and it is a ton of fun. The 
one problem I do have, however, is a miss under heavy load w/ high boost. I 
get 30 psig max boost in the higher gears and on a continuous incline with 
wide open throttle I can get a rather abrupt miss / stumble, it almost feels 
as if an IC hose has blown. I am off the gas immediately so I don't know if 
it would continue missing. Back on the gas and the boost builds back up 
normally.

Driving solo with less than a quarter tank of gas and the miss does not seem 
to come into play. Several people in the car, full tank of gas, uphill, 5th 
gear, WOT, 25+ psig of boost and the miss comes back.

Major service 5,000 miles ago including the proper F5DPOR plugs. I have 
checked the rubber boots on the ignition coils and they seem good. I have 
yet to hook up a fuel mixture gauge to see if I get a lean condition upon 
miss / buck. The computer seems to back off boost the way my TAP computer 
did (albeit with a max of 30 psig as opposed to 22 psig). Two of us are 
running the same setup (a S6 too) and we both have the problem since 
stepping up to the Stage III setup.

I know the 3B motors running elevated boost levels have had problems and 
that the conjecture has to do with the ignition rotors. How about the AAN 
motor with its distributor-less ignition? Potentially a weak coil on my AAN 
motor? Is there a way to check the coils?

Any suggestions would be greatly appreciated. Is 30 psig (3.04 BAR) just too 
much boost under load? I tried running some octane boost to see if it made a 
difference, but it did not. One would think that if the miss is detonation 
related to the high boost levels that running higher octane would either 
lessen the severity of the miss / buck ar at least its frequency?

TIA,
Frank--

PS I am off the list so please respond directly.