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Dwell and spark duration MX5 NA


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doing a bit of research on the stock 1.6L MX5 1989 NA

seems the standard ECU has 5ms dwell and 8ms cranking dwell.

stock spark duration is 0.5sec


G4+ mx5 map has it set at 3.5ms dwell and increasing with decreasing battery voltage, and  a1 sec spark duration.

I cant see anywhere for a cranking dwell input (unless during cranking assumption is battery voltage will drop below 12V?)


do you recommend to change the values to the stock numbers?

car is basically stock apart from intake and G4+


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The spark duration setting doesnt matter in your case, it is only important on engines where you have limited charge time - like a V8 with a single coil/distributor.  With 4 cyl wasted spark you arent going to run out of cycle time until you get to about 10000RPM.

I have no idea where the dwell time table data in our base map came from but it seems to work fine for most users, even boosted.  If you are sure about the accuracy of your data then you have the ability to adjust that table however you like. Right click on it and choose "axis setup".  You can add an X axis to get the "cranking dwell" increase.  You could set up a table something like below.  This would give you 8ms below 300RPM.  5ms at normal run voltages above 400RPM.


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