Friend is updating his E30 racer. Swapped an M30 in, wanted more power this year, freshened it, shaved the head, added a cam, so megasquirt to the rescue.
It's running a magnetic 60+1 crank sensor. Scope the crank sensor at the ecu, it looks like a 2 volt bias voltage, and about a 4 volt pattern when cranking. It won't start, unless it has sat for a few hours. Then, it will light for a second or so, run well, then lose injector pulse. Power supply is a steady 12 v, when it does start, scope shows a good pull down.
The laptop will drive everything just fine in testing.
I thought about clear flood mode, but the tps says 0 to 100%, in the proper scale.
That is at cranking speed, 0 to 14 volt scale.
Any ides?
Further, I got owner to turn the cranking rpm in the ecu down to 200 rpm, and it started, and revved up. Quit when I let it back to idle, and there's no rad currently, so no long running.
Progress, though.
The composite and trigger logs will be your friend at this point. I can't tell from the photo if that's the OE Bosch VR sensor or a Hall sensor, but the output definitely looks more like VR AC voltage. Your description sounds like you are expecting a Hall sensor. Factory trigger wheel is supported in Extra code, so no issue there. You didn't mention what MegaSquirt you're running but it looks like the DIYPNP with Bosch 55-pin. Anything MS2 and up will do all you need for batch fire with wasted spark or even semi-sequential with a cam trigger (guessing that's not included by the blockoff plate). Make sure the trigger offset is set right (about 90* IIRC) and you have the VR electrical input set up and jumpered correctly with requisite bias/pullup/pulldown resistors.
60+1 is a strange pattern, make sure its that and not 60-2
Use tooth logger in the tunerstudio diagnostics tab. Crank and post a picture.
2 volt bias voltage? is the crank sensor grounded to the right place?
My gut feeling is that the cranking pulsewidth just isn't big enough. The cranking RPM is just the point where it switches from fixed cranking pulsewidth to running off of the VE table.
Maybe it's apples to donuts but I found that a good cranking pulsewidth on a rotary would have the engine idling at richer than 10:1 if I had the cranking speed set too high. VE is near 100% when cranking because of how much time there is.
First, it's a BMW, so I don't care.
Bosch 55 pin sounds right.
Yes, 60-2.
No duty cycle at all cranking. It would fire for a moment and die, lab scope shows no injector pulse at all when it won't fire. I got him to drop the cranking rpm setting from 300 to 200, it fired up and ran. I'm not sure why you need that setting, but hey, I'm not the programmer.
I think I am steering him in the right direction, just based off 44 years of fuel injection time. It ran for a while, obviously not really well, but close enough to have a starting point now.
This Saturday will tell the tale.
Cranking rpm is just a threshold that makes it go from crank curve to ve/ase/wue mode and from cranking dwell to running. Its important but usually ok to be a bit off.
Start w tooth log, on 60-2 it should have one tall bar and lots of little. If it looks lile that, gold. Two tall bars swap ignition input setting. That all looks good back to cranking fuel
The spec for the air gap on the crank sensor is 1mm. I suggested he close it up some, so he took it down to less than .5mm, and it fired right up. The lab scope waveform cranking before was 3ish volts, after, about 8.
