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Old 03-27-2012, 11:24 PM   #15 (permalink)
EcoModding Lurker
Join Date: Mar 2012
Location: Houston
Posts: 46

truck - '06 Chevrolet Silverado WT
90 day: 22.65 mpg (US)
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california98civic - do you have any small logger or scan gauge device able to measure engine knock? A widely used way to tune for gas mileage is to increase advance until knock then back off slightly, but then because you have no access to multiple tuning tables (VE, spark, throttle, pressure, airflow, rpm etc), you'd have to test for knock at WOT to be safe, then back off if it was knocking some at WOT (I thought all 1.6 civics of your year model had knock sensors). Short of that, a few degrees advance won't hurt anything (set back to stock for emissions time), unless it throws a code. If it throws a code after advancing the dizzy while driving, it's likely enriching the AFR and running in open loop (no fuel trims running off O2 sensors) then the adjustment was for nothing. Have you thought about a Hondata tune or do you already have one?

Originally Posted by jakobnev View Post
Actually, the notion of the ECU undoing your changes is a myth, it couldn't possibly, it doesn't even know you have made any! The reason the car must be put in test engine mode is that it fixes the timing to a certain value, in normal mode the timing might be all over the place, making it impossible to adjust meaningfully with a light.
This depends on the vehicle, some vehicles with cam sensors run off spark maps in the ECU and no matter how much the dizzy is turned or what procedure is used, timing won't increase or decrease (it'll just be really out of tune with respect to the degreeing of the cam). Also some vehicles can adjust base/idle timing with the dizzy but won't affect engine under load, depends a lot on the vehicle/ECU/distributor. Honda's are pretty simple.
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