Motorcycle EFI question

gametech

Member
Why are motorcycle ECU's invariably Alpha N setups. My Wolf has an IAT and MAP sensor, so why wouldn't the Protune software use SD instead? As far as that goes, why not use a MAF setup on some bikes? I understand the reasoning behind Alpha N on ITB setups, because of possible variance in MAP between individual throttle bodies. On a single throttle body like most American Vtwins, it just seems that SD would be better. This would also allow for a backup Alpha N table in case of MAP failure, just as many cars have. Or, like GM ECU's, you could add a MAF and have SD and Alpha N backups.
 

Jwooky

Well-Known Member
Not sure why, simpler maybe. I convert my MAF cars to SP (speed density).

I would prefer SD also. It would be more accurate, but perhaps real world not a huge diff.

Keep in mind, most still compare to a carb. (see above^^ post)
 

gametech

Member
Not sure why, simpler maybe. I convert my MAF cars to SP (speed density).

I would prefer SD also. It would be more accurate, but perhaps real world not a huge diff.

Keep in mind, most still compare to a carb. (see above^^ post)
I converted my GTO to SD because the turbo exceeded the hard coded MAF limits, but on my dad's whippled Silverado, I left the MAF but converted to a 2bar MAP for full functionality.
 

gametech

Member
I'm currently experimenting with lean cruise for fuel economy, as well as richer settings for lowered engine temps in traffic. The limits of the factory narrowband O2's and the S&S software are impeding progress. I'm thinking of using something like a Megasquirt fuel computer, but the Wolf really doesn't have many hiding spots for extra computer modules. As far as that goes, the V&H exhaust isn't exactly going to hide a wideband O2 bung.
 

BiggJimm

Member
Maf over speed density is definitely better. The name of the game is fuel control thus more power. GM flip flopped over this with corvettes and wound up with MAF. Mega squirt is an awesome company with plenty of solutions.
 

gametech

Member
Actually, GM still uses MAF and SD blending. For fast throttle transitions, the old style MAFs were far to slow for proper tip-in response, but even the newer card styles seem to only have an advantage in the amount of airflow they can read. However, instead of an old style VE table, the newer GM stuff uses a simultaneous multivariable calculation based on several different inputs for the SD part of the tune. This accounts for the possibility of variable intake length/volume, variable exhaust, and variable cam timing, as well as DOD. With the sole exception of individual cylinder trims, motorcycle ECUs are still using late 70's to early 80's style tuning. This need on a front to back air cooled motor for individual fuel and timing trims is what makes it so difficult to find a really advantageous tuning solution. The computer really needs to treat the engine as two separate one cylinder motors. It is also REALLY difficult to find someone who both understands tuning and looks good enough to ride bitch while holding a laptop to datalog. Tuning cars is SO much easier.
 

Jersey Big Mike

100K mile club
I'd also check this site out. This guy made his own EFI computer for several bikes. There are some other arduino projects on the net that might be interesting as well -- do a google search on DIY fuel injector control.
 
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