Custom made Multech 62lb Injectors
#43
11 Second Truck Club
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The dead times (latency) on the custom set and the OEM 8.1 Marine injectors are almost identical so I should be able to just change the IFR.
Inj... 6v.. 7v.. 8v... 9v.. 10v.. 11v. 12v. 13v. 14v. 15v. 16v 17v
OEM 1.39 1.10 0.90 0.85 0.85 0.78 0.76 0.71 0.61 0.51 0.41 0.31
Cust 1.41 1.14 0.96 0.90 0.82 0.76 0.75 0.69 0.63 0.55 0.46 0.35
Inj... 6v.. 7v.. 8v... 9v.. 10v.. 11v. 12v. 13v. 14v. 15v. 16v 17v
OEM 1.39 1.10 0.90 0.85 0.85 0.78 0.76 0.71 0.61 0.51 0.41 0.31
Cust 1.41 1.14 0.96 0.90 0.82 0.76 0.75 0.69 0.63 0.55 0.46 0.35
I know a few people using them w/o making any changes to that...only IFR...
#44
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I don't think you can just pop-in the Motos and change the IFR and run good. Without the correct Battery Offset Voltage(dead times) the PCM will always be off. That is why a lot of people can get their idle right but not part throttle or vice versa.
Ex:
Lets say your PCM needs to pulse the OEM injector 10ms (milliseconds) to get an A/F of 14.5:1 but because the injector takes 1ms to open once voltage is applied by the PCM then your injectors effective pulse is actually 9ms (10-1=9). Lets say that is your tune for half throttle. Now if the PCM required 50% less fuel at idle then it needs to pulse the injector 5.5 ms (not 5 ms which is half of 10) because it knows that it takes 1 ms for the injector to open and takes that into account. So to get 4.5 ms (50% less fuel) it takes 5.5 - 1 = 4.5ms. That is your idle tune.
If you change to injectors that have a 2ms dead time then the PCM would always be off because it has been programmed with a 1ms dead time. You can scale the larger injectors down, change your min/max pw and adjust your VE table on the dyno but then you go somewhere else with different atmospheric conditions ie. barometric pressure, temperature etc. the PCM will either over or under correct.
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