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Old 02-13-2014, 10:45 PM   #28 (permalink)
ever_green
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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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Now that the throttle has been tuned to perfection, I have moved on to other things like tuning fuel and timing. I have already increased part throttle timing without issues and now have been looking at idle timing. I was wondering what effects ignition timing has at idle and coasting on fuel economy? I have read lower timing during fuel-cutoff/coasting means less engine breaking. If so this is a good thing for fuel economy purposes? My current timing is set at 15* at idle and up to 30* when coasting at speed. For some reason the manual (5-speed) ECU calls for only 9* of timing at low RPM idle. Why the difference?


Idle Ignition Timing Table

as for fuel I have not been able to induce lean burn. Lowering values above 0 simply just sends the car to open loop. However I have managed to replace it with leaner numbers. This is how the fuel map looks like:


closed loop fueling table. To calculate AFR subtract from 14.7. Ie. -0.1 means 14.6:1 AFR. I simply replaced all values at lower RPMs with 0 to run at 14.7.
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