Injector nonlinearity

[51Ford]

I'm stuck for now using too large but well characterized injectors in my 51 flathead ford V8 engine. In the following curves, the red points were recorded at the running voltage (14.2V) and show a dead time of ~0.5 ms for PW greater than ~1.2 ms. My idle PW is just above this, at 1.4 ms, so that's good, but I'm having difficulty tuning the very low load parts of the VE table where is gets into the nonlinear range of the injectors. Increasing dead time to 1 ms helps stabilize tuning these low-load areas but introduces other problems like incorrect warmup enrichment. What I would like to do is modify the code to account for MinEffectivePW (1 ms) and MinLinearPW (1.2 ms), which I know for these injectors, for better fuel control. I have the math worked out:

For PWs greater than DeadTime and less the MinLinearPW:

extraPW = [1 - (PW - DeadTime)/(MinLinearPW - DeadTime)]*(MinEffectivePW - DeadTime)

PW = PW + extraPW

The problem is, beyond looking at the C code and seeing about the right spot to do this around line ~975 in the 3.3.2 code I'm looking at, I'm not sure how to proceed. Any help in how to implement this in the code would be greatly appreciated! For example, how to execute my expression in the correct C format... Best wishes, Ken

dead_times2 by kenhenry_06268, on Flickr

[51Ford]

OK, this may be more trouble than it's worth. I'm switching back to smaller injectors and will look into staged injection to support higher loads/rpms... Ken