so I always thought that injector constant was

old inj lb / new inj lb x old constant

but when leafy and I were going over the correct way to compute he told me its the other way around

new inj lb / old inj lb x old constant

so i out it in the way he told mt and the figure was 0.26700 instead of 0.11866 I had the right idea right?? also with the bigger fig in there the car runs like it has a cam and on the border of stalling.

trying to figure out why it will not let me write entire on the next thread.

thanks

The constant is a scalar to the calculation of duty cycle. Because you're duty cycle must decrease with increased fuel flow, if in the calculation of duty cycle the stock PCM multiplies by this scalar (this is the way Megasquirt does it), then your formula is correct, If on the other hand the PCM divides by this scalar, then Leafy would be correct. I don't use HPTuners, so I can't give a definitive answer.

Just as an example, if we assume the PCM does scalar multiplication. If you went from a 30lb injector to a 60lb injector and used Leafy's formula, you would be doubling the flowrate and doubling the duty cycle, which means you're commanding 4x the required fuel for a given VE.




I have no signiture

so stock was 24lb and new ones are 36 lb and old constant was 0.17800 whats the new constant???

If it were Megasquirt, it would be 0.11867. Like I said though, I don't use HPTuners, so someone else will have to give you a definite answer. Just going be a simple search though, that seems to be the way HPTuners does it as well. That is...

larger injector = smaller constant




I have no signiture

ok I was getting that number you came up with if......

24 / 36 x 0.17800 equals 0.11867

but was told to do it this way

36 / 24 x 0.17800 equals 0.2xxxxx

which would make sense why its bogging and wanting to stall because its getting 2x the fuel required, make sense???

Makes sense




I have no signiture

thats what i was thinking..

Leafy told you wrong.......

Old injector size/new injector size* Injector Constant = New Injector Constant .....






P&P Tuning
420.5whp / 359.8wtq

Yeah I messed it up in my head and then wrote it out wrong. I should have thought about it for another 5 minutes and realized that the ic needed to be lower.


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yup put in the new constant tonite and everything is fine!!

Which was 0.01186 by the way with the cobalt 33 36 lb injectors!!