DIYPNP cold start strange problem
 

Hi,
I'm trying to iron out my last few megasquirt issues on my '95 1.6.

When starting from cold with coolant temp less than about 10 degrees c (50 farenheight) the car instantly stalls due to too much fuel. At that temp I need around 8ms cranking, and then once running just over 2ms. What happens is that once started the injectors are running 4ms which instantly stalls the engine. The only way I can prevent the stall is with throttle opening. I have ase zeroed out so i'm pretty sure thats not the problem.

I think this started either when I fitted a trigger wheel to the crank pully or uprgaded the firmware to grant slenders latest firmware.

So I'm using a DIYPNP with pre3.3alpha5 gslender v2.8, with sequential injection. A crank posistion sensor, and the oem cam position sensor.

I have attached a log and my tune. Thanks for any help.

Just a few observations, I might be off but:

1. You have 0.0 priming pulse everywhere. Maybe set it to 5.0 for all temps or something.
2. Your ASE Enrichment Percentage is 0.0 across the board, this could be why it dies immediately after starting. Try something like 40 at -39, down to 30 at 91
3. Your ASE taper is 0.0 again, set it to a flat 500 across the board for now


Try making those changes & let us know what happens.

Thanks for the reply

ASE makes the problem worse as it adds fuel just after starting. The problem is that the pulsewidths are almost double what they should be after starting, its like i need negative ASE at cold temps.

your dead times are too fast at 13.2v, if you have stock 95 injectors, you need to use like 1.1 or 1.2.

You have Additional Banks 2-3-4 active, I dont believe you need to do that. Just use additional drivers for the seq. fuel, no need to have banks active.

You have VE Fuel trims on and two of the 4 tables are apparently adding a little extra fuel. This is the first I've seen these tables on the MS2 firmware, kinda neat.

Your req fuel is set to 3.0, so I'm assuming you have 1000cc injectors...I dont even think ID1000cc have a deadtime of 0.5ms at 13.2v, and if you were idling at 3ms of pw, I'd assume that to be like 12.0:1 AFR, not 15.0:1.

And that probably explains why your VE Fuel table has such high values...

and agian, explains your lack of need for the ASE and warmup tables.

Braineack

I have bosch ev14 550cc injectors, the dead times in my tune are the ones that were given to me on the injector specification sheet.

I've added extra fuel in cylinders 3 and 4 in an attempt to compensate for the fact that i'm still using the stock coolant routing and no dual feed fuel rail. The amount added is complete guesswork to be honest.

The required fuel is set low with VE numbers high so that I can get more resolution, so each increment on the VE table makes a finer change.

Is the transition from craking fuel to running fuel normally tapered or does it just jump from one to the other? Is there a way change this transition time?

I've played lots with cranking rpm but the best I can get it is with cranking rpm at 400.

good luck.

It goes:
crankingPW -> ASE/ASE-taper -> Warmup Enrichment -> Normal Operation


That's the RPM threshold that the ecu uses to determine if it's cranking:
if (rpm < 400) { cranking = true }

why thankyou