[s-cars] Potential reason why the "370" software causes pinging
Dave Forgie
forgied at direct.ca
Tue Dec 28 19:30:31 EST 2004
Over the Christmas break, I have been sorting and organizing my over 40
Audi S1, 20V UrQ, S2, RS2, S4 and S6 20Vt magazine articles. In doing
so, I found one that I had not looked at too closely before: The June
1994 issue of Rallye Racing has an article starting on page 50 about an
SMS Tuning S4 Avant that was tuned to 375 PS (Deutsche Industrie Normale
(DIN) horsepower). The article was comparing the result to the RS2
Avant. (The revised top speed for the tuned S4 Avant was 279 kph (173
mph)).
The interesting thing was they quote the compression ratio of the tuned
S4 as being 7.8:1 instead of the normal 9.3:1. Since "rumour" has it
the "370" software provided by some un-named persons is a combination of
SMS Tuning and Lehmann tuning software, it would not surprize me that
part of the reason the "370" software has caused my engine to ping is it
was originally set up for the lower compression ratio. I think the
reason the "370" software does not always cause pinging may have
something to do with altitude (thinner air at higher elevations
resulting in lower air:fuel ratios and less pinging). Since I am at sea
level, the combo of higher than expected compression ratio and denser
air is not good. "Fortunately" I have a VMAP which I have "tuned down"
to 2.8 bar (less boost). However, I do want to cure this problem. It
may involve new software and/or FMIC. (or a move to Denver or Calgary)
;>)
Dave F.
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