stock engine with megasquirt

[Pl3wA]

Quick question guys. Would a stock engine have trouble starting if the megasquirt ecu was tuned for a motor with .144 mls headgasket and 70lb injectors?
I would imagine there would be complications as there is probably a change in the timing and fuel amount etc to make up for the extra space and fuel in the cylinders.
Cuz that would be a pretty stupid fuck up if you axe me

[GunMetalGrey]

It wouldn't be the headgasket that would cause issues, it would be the injector size.
You could try to adjust Req. Fuel and just watch AFR's to make sure it doesn't run lean, timing will be off a bit I am sure but I cannot imagine it would be off too much.

[Pl3wA]

Then what could it be? Its a little too late haha since i let the engine seize but for a week i was adjusting the fuel with no effect.
Now im going to rebuild a b28 nv and try again!

Edit:
Also for a relatively old engine with a leak in the system the small dofference might have made all the difference

[nando]

all you would have to do is change the required fuel. it would definitely need tuned but it should start and hold an idle.

[Q5Quint]

As long as the pulsed minimum opening time for your injector is small enough for idle then you should be ok.

Are 70lbers hitting a 1ms pulse width at idle? That may be as small as they can possibly go.

I am getting like 1.25ms for 17lbers and 1.0ms for 70lbers.... but my math is old and likely wrong.

Random internet article so take with salt:
"Injectors should not be operated below 1.5-2.0msec PW’s due to the non-linear portion of the curve. At extremely low PW’s, the injector’s coil does not have time to reach its magnetic potential, thus the opening and closing action of the injector becomes erratic."

[nando]

it depends on the injectors. the siemens deka 60lb injectors are extremely fast, for example, and idle very well. it's also better if you use fewer squirts per cycle, or sequential injection. 2/alt or 1 simultaneous would be the first choice after sequential.

[ForcedFirebird]

If the calibration was for 70lb and you have 17, there's no way there would be enough fuel for it to start - not even close.

Nice thing about MS, though, is you can just go in the settings and change the inj size providing the previous tuner set the 70lb value while tuning. I accidentally tuned a car with 19lb injectors with the 14.5lb still set in the parameters - took me a few minutes to realize why it was barely starting and running very lean in another car when both engines were identical (except inj size).

So, in short, the car barley started and ran with 17lb inj in place of 19lb, can;t imagine you would even register an AFR when going from 70lb to 17lb.