- Sat Jun 19, 2021 2:41 am
Looking at original pulse to PRW2 ignitor, ignitor goes on (input high 10.5v) and coil starts charging, ignitor turns off (input low) and coil fires.
I have speeduino set to Spark Outputs Triggers = Going Low
I have the ignition output jumpered to 12v on speeduino
I never have scoped the speeduino output to the ignitor. I am guessing the way I have it set to have a similar pulse to the original output, but probably a near 12v peak voltage and slightly shorter dwell. I analyzed the original ecu and system before installing speeduino, so I did not have a lot of trial and error, it just seemed to follow my calculations.
I probably have much more than 1000 miles on it, and lots of run time in the driveway. Everything seemed to be running cool and correctly as far as the ignitor/coil were concerned, I did check temps.
Curious about the long dwell time of the Nissan original system, I did reduce dwell until I was getting misfires. These times were under 3ms but I forget exactly. I know around 3ms dwell is recommended for most and this seemed to work ok. I compromised at 3.5ms running dwell, as I didnt want any possible misfires during initial tuning.
I have built and tuned many other efi systems in the past, and had access to all the data I needed before I set this up, so I dont believe that I prematurely abused this 4424.
I am very surprised I didnt melt any traces on the board, smoke the 4424 completely or the ignitor, or coil. Like I said when this didnt start (the only time I have had a failed start on the speeduino btw), I had the key on for 15minutes or more at a time trying to find the problem.
Once I found ignitor was too hot too touch, I quickly disconnected it. I then checked speeduino and found the LED lit, and the 4424 too hot to touch.
Is there very little failure rate of the 4424 under normal conditions? Maybe I got a bad chip
Does too little of dwell for the ignitor and coil cause excessive current or problems in any way? I wouldnt think so but am looking for ideas
Perhaps I had a weird startup glitch, where speeduino reset or my crank triggers were in an odd or reverberating condition? I would think overdwell protection would protect this but maybe something strange happened.
I am going to buy some more 4424 as backup, and familiarize myself with re-configuring the ignition output pin in the code in the meantime if I fry my last one. I should be able to look at datasheet and cut a bad leg off a half-dead 4424 correct?
I appreciate the help, thanks!