efi Megasquirt Cranking Pulse Width

[mike472]

I have my car almost starting and I thought the cranking injection pulse width might be off from what they have as default settings. Besides almost starting I'm getting a backfire every 20-30 seconds. Anyone have a screen shot of what percentage pulse width vs temp they are using?. I tried going up but wasn't sure how much. Ended up flooding it a couple of times. Hard to tell if it's too much or too little. Any other adjustments people made during startup would be helpful. I went down the checklist in the mega manual and they said this usually needs adjusting to get the car to start. The after start enrichment settings and priming pulse settings you used would be helpful too.

[Harv]

Backfire at starting could be too lean.

John

[jimk]

If it starts and dies, the cranking pulse is ok, but the after start is not.  Increase after start by 10-15% and it should be better.  If it still dies, give it more.  The after start and warm up are very difficult to hit on and are done following the low speed tuning on a hot engine.  So you have one try each day on the cold start and your luck should improve after 4-5 tries.

After 20-30seconds of running if it has stumbling and backfiring, quit messing with the after start settings and switch to making adjustment to the warm-up settings.  If you diddle with the fuel table after it is heated up (above 140F) then all the cold settings will be off and it's try again tomorrow.

Edited June 1, 2014 by jimk

[TobyB]

Jim, you make it sound just like a carb...

heh...

 

t

[jimk]

Jim, you make it sound just like a carb...

heh...

 

t

After setting up 6 different ECUs on my car and helping several others, -----

[mike472]

If it starts and dies, the cranking pulse is ok, but the after start is not.  Increase after start by 10-15% and it should be better.  If it still dies, give it more.  The after start and warm up are very difficult to hit on and are done following the low speed tuning on a hot engine.  So you have one try each day on the cold start and your luck should improve after 4-5 tries.

After 20-30seconds of running if it has stumbling and backfiring, quit messing with the after start settings and switch to making adjustment to the warm-up settings.  If you diddle with the fuel table after it is heated up (above 140F) then all the cold settings will be off and it's try again tomorrow.

Jim,

 

Are you adjusting the After start Enrichment taper or the After start enrichment percentage or both?  Thanks for the tips.

[jimk]

Jim,

 

Are you adjusting the After start Enrichment taper or the After start enrichment percentage or both?  Thanks for the tips.

Can't help you there.  I have never used Megasquirt.  On all the ECUs I've  used, they taper and depending on your preference the time over which the taper occurs is your preference, but set both the percentage and taper time..  Following the after start taper, the warmup is supposed to keep things in tow.

Edited June 1, 2014 by jimk