98 NB dwell settings with stock coilpacks
 

Hi,

I mentioned this in passing in my other thread but I think there's more to it than I realised.

What are the 'correct' cranking and running dwell settings for a 98 (99) NB with the stock ignitors? I am using a TC4427 with the inputs connected to the D14 and D16 outputs.

The default cranking dwell in the DIYAutoTune basemap is 8ms but at that setting it just backfires and hangs the starter up like there is way too much advance. If I change the dwell to 3ms it will start but is very hard to start. once started it runs relatively OK.

Are these dwell settings atypical for the stock coilpacks on the NB? Is something screwy about my setup?

Cheers.

Make sure the spark outputs are at 0V with the key on and engine off, not 5V.

Yep, 0v with key on but engine not running.

LEDs flash as expected when the coils are firing.

This is the ignition driver circuit I'm using:

https://www.miataturbo.net/attachmen...ine=1466528784

One thing I've just realised... I'm using 10 ohm resistors in place of 15s there (it was what I had, and I assumed the function of the resistors is just to limit inrush current to the mosfet gate inside the coils).

Also I'm using a TC4424 instead of a TC4427... supposed to be functionally the same but have a higher output current ability.

Could that have anything to do with it?

Cheers.

I've set the cranking dwell to 6ms. Now starts on the button. Not sure why it doesn't like 8 still, perhaps I have weird coilpacks.