With some pcm tuning can you keep an AFPR's settings where you want them. Say if i leaned the car out to 37 psi's, Ive heard the computer will reset itself to its factory settings. Is there anyway to stop this?

 

http://www.bryantperformance.com/396_calibration.html

This is good reading, plus good links. The pcm well relearn, changing fuel pressure is a temp fix. Some use injector constant, others use maf calibration, to change fuel deliverly. In open loop the pcm is always going to try to get 14.7/1 afr, you make your adjustments to keep your blm's as close to 128 as possible. The blm's affect afr in pe mode.

 

Just to make sure you understand.... the PCM can not change the fuel pressure. If you set it at 37psi, it will stay at 37psi. What the PCM does is increase the BLM's to produce a longer pulse width. If effect, the injector flows less in a given period of time, because the fuel pressure has been reduced, and the PCM keeps the injector open longer to keep the total fuel flow per pulse constant.

You do NOT want to tune the engine with an AFPR. You want to enter the correct injector constant (and that is determine, in part by the actual fuel pressure) and offsets. That allows the PCM to operate in closed loop with minimal BLM changes. Then use the PE tables to adjust the target A/F ratio at WOT.

There is really no reason to use an AFPR unless you want to increase the pressure to squeeze a few extra HP out of a set of max'd out injectors. And that's not really a good idea either... just get larger injectors.

 

Last post was correct. The pcm will compensate for a condition that is either richer or leaner than desired, based on desired afr. The same person that created that theory must have been the same one that thought that dry nitrous was a good idea, and that the fuel gods would save your motor.

The higher fuel pressure is useful for slightly increasing effective injector size, and/or increasing fuel atomization via higher pressure-oem has been raising their fuel pressures a bit over the last 10 years for that reason. Hope this helps ya.

jim