Could someone please explain the need for different maps for Cyl1 and Cyl2?

MBJST

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Apr 15, 2017
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Baraboo, WI
I've been reviewing the maps via FlashTune and see, at some RPMs and throttle openings, a rather noticeable difference between the maps for Cyl1 and Cyl2. I suspect either a cooling thing because of the cam chain on the side, or (what I really suspect) because this is a big bang engine. Am I out to lunch or is there something else? Has anyone ever balanced them out?

Sorry if this has been covered before. I searched but didn't have any luck finding anything.

Thanks
 

yoyo

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I didn't realise that was done on the S10, when I had a Strom having 2 each cylinder mapped was common due to different lengths of header pipe.

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Checkswrecks

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Could be any number of differences, and the designers probably couldn't tell you either. This is the kind of fine tuning that is done on a dyno, when taking a prototype is being developed for production.
 

blitz11

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Without seeing the mapping differences, this is only speculation, but one cylinder might be set up rich to reduce NOx emissions, and one might be set up lean to reduce COx emissions. With two O2 sensors (one for each cylinder), when in closed loop control, each cylinder can be controlled independently, allowing this optimization of emissions.

My 1992 volvo does this in a different way. With one O2 sensor in closed loop control, it runs rich for a few seconds, then it runs lean for a few seconds, as a means to balance NOx and COx emissions. Pretty good idea - i wish i had thought of it. When you go WOT, it is configured to run pretty rich.
 

ace50

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Another possible reason for the difference is, it is a 270° engine.
Maybe to smooth it out a little???
I do wonder what it would be like with similar maps....
 
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