[E4ODnut]

I've been working with my old v0.4 board on a simulator experimenting with different settings and checking the results on a digital signal analyzer. I've noticed something that probably isn't an issue in real life, but it would be nice if it could be fixed without too much trouble.
I'm using a 36-1 wheel on a wood router with a VR sensor going through a dual VR conditioner from JB Perf. The set up is for a 4cy, 4 stroke engine, waste spark, paired injectors, 2 squirts alternating. At slow crank speeds I'm getting chattering of the fuel pump relay until the period between teeth is less than about 34.645mS, which is about 48 RPM on a 36-1 tooth wheel. After that everything works beautifully.
A thread from a few years ago about hand cranking caught my attention. As I see it, if the engine is primed and you start the swing about 6 teeth before the missing tooth, you should be able to get the engine to fire on #1 and you're off to the races. If nothing else I think that would be a pretty cool thing to be able to demonstrate.

[PSIG]

If doing something unusual like that, I would simply add a cranking bypass switch to power the FP during start, or a very long priming time. Switch it off during run, so it is ECM-controlled for safety. Chattering is simply a lack of hysteresis at the threshold of minimum cranking speed. Cranking should achieve and maintain higher than threshold.

Older code versions had a Basic Distributor "fixed to trigger" feature similar to trigger-return, that fired spark on crank signal. This generally worked for hand-cranking, push-start or kick-start, as the primed fuel would fire and kick the engine above threshold so everything worked. Alternatives are things such as GM HEI module Bypass or equivalent, allowing spark at any rpm, returning timing control to Speeduino when it was above threshold.

[E4ODnut]

Bypass switch sounds like an easy solution to me. Thanks.

[dazq]

Bypass switch sounds like an easy solution to me. Thanks.

It is not unusual even with OEM to have the crank position of the ignition key to override the fuel pump to run while cranking. Simple to add a relay to do this or even a simple diode if the keyswitch permits it.