pcmhacking.net

Hi guys
P59 7603 with lean cruise ON (without patch -just oem settings for 7603)
In attempt to tune lean cruise I found that if I press accel fast -AFR drops to lean +1+2 to 'normal' mixture for 0.1-0.5 sec
If I drive with 14.7AFR -it goes to 16-16.5 and back to 14.7 and not feels at all as a problem
But if I drives at lean condition 17AFR and trying to overtake -it drops to 18.5 or lower(sometimes engine trying to die) and start misfiring badly
Where can I increase enrichment by TPS ?

There are transient fueling tables that accomplish what carbs did with accelerator pumps, but they usually only need to be altered if you have some sort of aftermarket intake manifold. Most of the time transient fueling issues are caused by your main VE and MAF tables being wrong, which is also often a byproduct of the fuel injector data being wrong. Also, this isn't really the best forum for engine tuning questions.

Accel enrichment is handled by some MAF scalars that offset how fast to smooth rapid MAF movement[Maf reacts much faster and need smoothing so fuel don`t jump back and forth]. Need to dig out exact tables.

Ve tables might not have accel enrich at all.

I dont think anyone looked into details about it. Which OS your running.

P59 '7603 is OSID 12587603

kur4o wrote: ↑Mon Mar 31, 2025 9:00 pm Accel enrichment is handled by some MAF scalars that offset how fast to smooth rapid MAF movement[Maf reacts much faster and need smoothing so fuel don`t jump back and forth]. Need to dig out exact tables.

I think that it should be faster than MAF readings cuz as far as I understand when maf shows exact numbers AFR restores to normal
Problem with over leaning only lasts less than 0.5 sec if throttle was pressed fast enough

gametech wrote: ↑Mon Mar 31, 2025 1:15 pm There are transient fueling tables that accomplish what carbs did with accelerator pumps, but they usually only need to be altered if you have some sort of aftermarket intake manifold. Most of the time transient fueling issues are caused by your main VE and MAF tables being wrong, which is also often a byproduct of the fuel injector data being wrong. Also, this isn't really the best forum for engine tuning questions.

Maybe
But at least there are bunch of experienced guys that navigates thru tables much much better than me
I only need to know where is/are needed parameters to adjust em to rich enough that if I press gas pedal quick my AFR goes to reach not lean
I changed ignition sys to MSD 6AL(capacitor discharge ignition) -looks like it handles better 17+ afr mixture (engine now not trying to die with 19-20 AFR and restores target AFR quickly)

There is no "pump shot" or "acceleration enrichment" table like an aftermarket ECU would have. The factory computers use a series of tables that are all interconnected in order to calculate how much fuel to add. The calculations are completely based off the idea that your base fueling is correct. What you think is a simple question is anything but simple. Read up on the Hptuners forum for more info. It is free to join even if you don't have their product. Just be aware that most Tunerpro XDFs will list more tables than Hptuners has made available, and some of the table names may differ.

There is 18 zones dynamic air fuel scalars, that adjust MAF reading, much more complex with lots of variables.

There is also some tables that define the zones boundaries.

There is also maf and SD blending with some percentage weight.

Basic theory is MAF jumps 10g/s. The air didn`t enterered cylinders yet, pcm scales down the 10g/s increase in increments over a defined period of time, so fuel is done like this 100g/s to 110g/s change is done in 20ms increment by 1g/s.

These scalars usually define how fast and step size being used per different conditions.

There is vaguely any description how to tune it, so without some RAM logging of specific data, it is impossible to really figure the math logic flow.

gametech wrote: ↑Thu Apr 03, 2025 3:00 pm The calculations are completely based off the idea that your base fueling is correct.

The only difference I have from stock -delete restriction inside throttle (delete added metal onto throttle blade)
But it not helps -95kPA at full throttle

V8fan wrote: ↑Sun Mar 30, 2025 7:55 pm Hi guys
P59 7603 with lean cruise ON (without patch -just oem settings for 7603)
In attempt to tune lean cruise I found that if I press accel fast -AFR drops to lean +1+2 to 'normal' mixture for 0.1-0.5 sec
If I drive with 14.7AFR -it goes to 16-16.5 and back to 14.7 and not feels at all as a problem
But if I drives at lean condition 17AFR and trying to overtake -it drops to 18.5 or lower(sometimes engine trying to die) and start misfiring badly
Where can I increase enrichment by TPS ?

The only way that I'm aware of turning on lean cruise on the 7603 OS is through the patch. You can change all the settings in the lean cruise parameters, but it will not do anything unless the patch is used. If you figured out a different way of turning it on, would you mind sharing how and posting your tune file?