I can buy the argument that running rich does cool the combustion temperature. When the fuel/air ratio is correct, the combustion occurs in the combustion chamber, very rapidly, almost a detonation. If the mixture is too rich, the burn won't happen as quickly or as fully and the rest of the combustion will take place in the exhaust manifold as the gas expands (high EGT's). I'm not a combustion engineer or an engine mechanic, just a theory.

What I can say is that my car has been much happier since tuning the ALDA. I wound up a full 3 turns CW. Just about 1/4 turn CCW from fully CW. No smoke, good power, smooth running, and the fuel consumption has gone down significantly. Currently a little over 280 miles on 1/2 tank of fuel.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)