Originally Posted by
cobaltssoverbooster
short answer is yes thats how you interpret the error feedback.
yes you can tune the offsets this way. ive done it a few times against my own recommendations when running unknown injectors with no readily available data on 1:1 regulator systems.
i measure the injector flow of one injector in cc at the desired rail pressure. this gives you cc/seconds. you can then convert this data to cc/min or lb/hr and enter this into the base flow IFR chart.
testing the IFR rate you add 10 % to a tuned in ve table. if the error reports back -15% then you need to remove some trim from the offset table. basically the multiplier is adding too much to the base flow and causing an over-fuel event.
same but in reverse for going -5% after adding 10% fuel to base.
occasionally i got a set that doesnt want to go along with this method and i apply a technique thats probably not going to make people happy but it does work fairly well as a last resort when sending injectors out for flow testing isnt an option.
set the voltage modifier to 0 from 13v to max volt. then upload voltages from a similar injectors flow data for voltages below 13v.
from here i tune the ve in at idle and monitor the system voltage.
i create a histogram that plots afr error against system voltage in the same format as the voltage modifier table.
i start recording the idle and then pull the alternator plug which slowly drops the system voltage since the alternator is now not supplying any charge source. i keep doing this until the system voltage gets to 10v which is where i call it quits so i dont kill system components like say the battery, ignition coils, injector coils. leave the voltage offset data from below 10v as the data you swapped in from a similar set.
the idea behind this is if you tell the ecu the injector flows the IFR rate at fully charged then this is where its going to be when you drive assuming all is well. to do this the voltage multiplier is 0 which means there is no flow offset to the IFR table. Most batteries are 6 cell batteries measuring 12.6 volts at full charge which means each cell is 2.1 volts. if a cell drops then it usually shorts an adjacent one out unless you have a spiral cell battery like an optima which keeps them isolated. if an optima shorts a cell then it drops to a max voltage of roughly 10.5 volts, but for most people the standard battery can take out 2 cells which drops the max voltage output to 8.4. this is why you cant start your car when the battery shits itself. most starters need a bare minimum of 10 volts supply (unloaded, no current flowing) to start a battery because they can drop that source 2 volts or more when loaded by the starter. Since the voltage at failure drops below a safe tune-able spot your going to end up fixing the problem before you ever need to run for a substantial period of time requiring that low voltage offset to be correct. now some may say the voltage does vary at startup when the vehicle sits for long periods of time or just over night. to counter that, calibrating to 10 volts allows the system to micro drain over time and still run accurate enough to allow the charge system to pick back up during run time.
I will mention again that this technique is fairly crude and isn't recommended unless your at the very end of all other options, so dont be like i should do this first then work it out. No! i still recommend sending them out for flow testing first, finding a similar data set to test second, and then last chance this way for a possible hail marry.
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anyways I'm sure not what the injector slopes are for
The Injector data I calculated is for 43.5 psi fuel rail pressure and lowest I could get the regulator to go was 46 psi and I can post my tune if you'd like