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Old 05-20-2015, 03:50 PM   #1 (permalink)
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Join Date: May 2011
Location: Toronto
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gueff - '19 Mercedes Benz A250 4MATIC AMG
90 day: 30.55 mpg (US)
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Lean Burn in my Subaru - need help


I solved the previous issue of higher fuel consumption with lean burn at highway speeds. The problem was too little valve lift (similar to insight vtec crossover). I just had to initiate the high lift cam lobe sooner (at highway speeds).

Now i'm commanding about ~16.5 AFR between 25-55% engine load (highway loads). As soon as one climbs above 55% load the ecu will inject extra fuel to purge the excess NOx from the 1 CAT I have (~13.9:1 AFR). It will also do the same once you let off the throttle. I know Hondas can go even leaner and I'm contemplating doing this as well...but i'm not sure how lean and also what sort of ignition timing they run and the consequences? I'm doing about 39-47* IGN depending on load at said speeds (10:1 compression head and a Honda-like pentroof chamber).

Last edited by ever_green; 05-21-2015 at 01:17 PM..
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