Gavin Posted February 8, 2007 Share Posted February 8, 2007 Since I upgraded to the ZXT dizzy for my trigger, I have had a very strange cranking problem. The car will always start fine with a Cranking RPM (under general settings) of arround 70-90 RPM - Less if I have a low battery and more if its well charged, but it will not start out of that range. It does not appear to be using my cranking PW with the RPM set like this, but instead I guess is pulling them from the VE table. If I try to set it higher, like the normal 200 RPM, it violently backfires. I find that the engine is not fussy about its starting parameters, almost never flooding at times when it really should have and under a wide range of ignition advancement in the cranking area of the table - right now that area is set to 0 advance while I finally try to sort this out. Here are my ignition settings: So, what could be causing the misfire? And why on earth would it need to be at this particular cranking RPM in order to start?? Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted February 8, 2007 Share Posted February 8, 2007 It looks like the problem is that you're running a trigger angle of 70 degrees, but you've set the cranking trigger to Trigger Rise. When you have this setting, if the RPM signal is below the cranking RPM threshold, Megasquirt completely ignores the trigger offset and fires the coil as soon as you get an input from the ignition trigger. So your crank timing will be way off. Change that to Calculated. Quote Link to comment Share on other sites More sharing options...
Gavin Posted February 8, 2007 Author Share Posted February 8, 2007 Niice. I'll go try that. Quote Link to comment Share on other sites More sharing options...
Gavin Posted February 9, 2007 Author Share Posted February 9, 2007 Did the trick. But its behaving very strangely now. Should I have to reset my base timing? Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted February 9, 2007 Share Posted February 9, 2007 You may very well have to adjust the base timing a bit with the new distributor. Quote Link to comment Share on other sites More sharing options...
Gavin Posted February 28, 2007 Author Share Posted February 28, 2007 Thaught I should report back- Yes my timing was out of wack. Fixing this actually helped my throttle response a huge amount as well as cranking, as is used to hesitate for a moment when I got on the throttle (assumed it was an enrichment problem before). Quote Link to comment Share on other sites More sharing options...
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