Background: I replaced the stock 19lb injectors in my '92 LB9 with Accel 30lb'ers. I then corrected in my bin the injector flow rate and proceeded to tune my VE tables accordingly. This was a year ago.

Ever since the swap, my engine seemed to take just a couple extra cranks to fire, and when it does, you can hear 1 cylinder, then a couple others, then it begins to idle. If I push my gas pedal ever so slightly when I turn it over it corrects all of this and it fires right up as before the swap. Also this happens year-round in all temmperatures.

Now my question. I've taken my Crank Pulse Width Vs. Temp. parameters and increased them 13-14% across the board. However I have a few thoughts about that. First, does the injector flow rate have any influence upon these parameters? I mean should I even need to mess with the Crank Pulse Width Vs. Temp. parameter? Or on the other hand, do I need to significantly lower this parameter because my injectors are so much bigger and the flow rate doesn't correct? Does pushing the pedal even effect the injectors on crank or only once running? Is pushing the pedal adding fuel or simply allowing more air and correcting a rich issue? Do you see what I am trying to get at?

What do you guys know/think? Do I need to add fuel, take out fuel, what?

Thanks!!!!!!!!!

 

Take fuel out.

Crank fuel is a pulse width. If you put larger flowing injectors on there, then they flow more fuel in the same pulse width, which in your case is causing it to almost flood.

I've found that if it "fires" on a few cylinders but just can't run up, it's usually too rich. If no fire, it's too lean, or WAYYYY too stinking rich, but that's very rare. The sound of the firing cylinders can tell you rich or lean with a bit of practice (but typically only necessary at very cold engine). Using the stock calibration (and compensating for injector size) is usually good enough (along with adjusting base timing on the distributor and chip - depending on the engine).

Some ECU masks have a throttle multiplier to the crank PW, and can both enrich at part throttle, and clear flood (go extremely lean) at high throttle. The extra air with cranking with a slightly open throttle can help some (15% more air at most, I'd guess). But it's probably a good sign that it's too rich if it does help significantly.

 

The $8D mask has a crank PW scale value. Best bet is to reduce that by the ratio of the stock injector vs. the new injector flow. That will get the engine real close to the same crank PW's during starting. Dependent upon the engine modifications you may still need to tweak it a little.

L83AD: FDB 13108 ; SCALAR FOR MAX PW

RBob.

 

I agree with RedGold. You are most likely on the rich side at engine crank. Mine would start right up fine cold, but a warm engine would crank longer. I lowered the Pulse Width at specific temps, to help my crank times.

I would keep all the multipliers set=1.0. Then just adjust the crank fuel PW vs coolant table. That way you know exactly what you got for starting PW. Also, if you give it throttle at startup, and you have all those multipliers =1, then you are adding air to help a rich startup condition.

But just a reminder, you may want to decay the PW down after several DRPs, so you dont flood it out.
HTH