Monday, October 10, 2011

Working on a reliable start

There's only a few variables that can be changed for starting and a majority of them I've been able to copy from the OEM ECU.  Spark advance and dwell are easy.  Priming pulsewidth is relatively easy.  What's been kicking my arse is the cranking PW.  In order to make some sense of when it starts and when it doesn't start, I've been logging each start with the CLT temp, and cranking pulsewidth and putting it in the "Yes" or "No" category if it starts on the first try.

EDIT:  At the time the graph was discouraging because it made it look like starting was a 50-50 affair.  In retrospect, it really was a 50-50 affair because the cam signal wasn't working.  If the motor was in the right phase it started and ran great, if it was in the wrong phase it just didn't start...  It was 50-50.  When it did start, it ran full-sequential which made me think the cam signal was fine.

It was never a starting problem, it was a comparator threshold voltage problem.

EDIT, Dec 2011.  My remaining starting issue was caused by the fact that my starting circuit transistor was losing biasing under low-battery conditions, mainly when it was cold.  Since I re-build that little circuit it's started 100% of the time on the first crank!

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