[info] uaEFI

[alant]

Hello, doing bike EFI retrofit using uaEFI. Tried to use stock VR sensor (I added digital hall sensor to camshaft for phase). Stock trigger wheel is 6mm thick/wide with 4 short 1 long teeth. After several attempts to get 24 teeth trigger wheel from 8mm mild steel on cnc laser best result was taken and post processed on lathe. It was not possible to find such speed/power config on laser so each tooth is perfect. Tried stock sensor and the best wheel I could cut on lathe. Lathe is vector VFD controlled with hall sensor for rpm measurements. 100rpm was 300mv p-p sine, 2200rpm was 24V p-p, and I suppose it will be ~130V p-p at 12000 rpm (hard limit of engine).

Oscilloscope showed clean sine BUT due to few tooth having slightly variable shape some sines are bit phase shifted as seen on video.

So I have some questions:

1. Should I limit voltage via some voltage divider to not burn uaEFI circuits with 130V sine input? Should I increase gap with VR so voltage is lower everywhere? If gap increased 100rpm will be not even 300mv p-p will uaEFI catch that at all to start up engine?

2. Can camshaft sensor send trig signal at some weird angle before TDC of some cylinder? say 137.67 deg BTDC #3? can it be entered into config or I need to have it as close as possible to 0.0deg TDC of some cylinder to make things happen? I will not use missed tooth on trigger wheel on crank, is it ok?

3. What with phase drift of sines? Does uaEFI calculates time between two tooth to use as input for derivate/integral calculations in engine math model to get idea of accelaration after combustion of each cyli der to check for misfire and/or balance them(cylinders) out via spark advance and/or injection tweak? Are there any theoretical/practical numbers of accepted phase drift when internal digital filters can coupe with trigger wheel tooth position deviations? Seems like there is some IC in input for VR, does it filter/normalize/average signals?

[AndreyB]

Max9924 datasheet? Do not worry about 130v on VR

Yes, Totally configurable

3. I think you are overthinking it a bit, with non linear revolution we dk not need that much precision

[alant]

Max9924 datasheet? Do not worry about 130v on VR

Maybe I read it bad but is says VR inputs (IN+-) are 0 to VCC and VCC is up to 6V...

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Just to check twice 300mv p-p is enough for built-in IC to reliably get position and start the engine? I'm not familiar with VR specifics thats why asking...

3. I think you are overthinking it a bit, with non linear revolution we dk not need that much precision

I'm worried about possible misfires or extreme ignition advance. Absolute phase shift according to oscilloscope is 1/13 of period i.e. ~7.7% and in persistance mode I can see that it is like 1 tooth going too advance and 2 teeth retarded and the rest are too close to distinguish (one bold line). Given I have 24 teeth total (360/24=15deg per tooth) and maximum deviation is 7.7% I have 15*0.077=~1.15deg of error max in positioning using raw signal. Are there some algorithms involved in firmware that do some digital filtering on assumption that tooth-to-tooth transition can not be faster than some mechanically achievable acceleration?

[AndreyB]

discord time?