Injector Duty Cycle PID

[roastin300]

I am trying to chase down why I am running lean under WOT. In open loop, MAF de-activated, PE turned off, tuning the VE table only, I have richened it up to a point where it wont go below ~ 14.5-15:1 (PLX Wideband) at peak load @ ~4800RPM. Any increase in VE Table in this area makes no difference now.

How accurate is the Injector Duty Cycle PID that is in HPTuners? I looked and it shows over 100% duty cycle where it starts to run lean.

Could it really be maxing out the stock 28 lb/hr injectors? Mods are stock LS1 longblock, 1 5/8 in shorty headers, full exhaust, LS6 intake manifold, ported TB, big 4 in intake plumbing, 85mm MAF. Thanks guys!

[danieloneil01]

Post a tune and log.

[roastin300]

Here it is. I am targeting 13:1 in open loop for all cells, which for gasoline with an assumed stoich of ~14.7, Equivalence Ratio = 1.13, and lambda = 0.885. Thanks

[gagliano7]

http://www.hptuners.com/forum/showth...682#post109682

[jim2092]

Isn't 4800 rpms too high with the PE turned off?

[johnm545]

If you're maxing out the stock injectors on a stock LS1 you have low fuel pressure. Pressure will be sagging under load. 126% VE just doesn't happen on a stocker unfortunatly!

It's fine to disable PE if you've set up the open loop fuel/air table properly for a rich mixture accross the board while tuning (which you have).

Tune looks good otherwise. Log would be good to see.

[roastin300]

Ya the only reason it is 126% is because anything added in over about 100-105% was making no difference on my AFR under WOT. I am thinking the fuel pressure is dropping as well. Time to put a gage on the rail and set it on the windsheild and see. I have a Walbro ready to roll if needed.

[Bill@HPTuners]

max net engine tq. This table can affect fuel pressure as stated in the scroll over help, might start there

[vannatta20]

I had the exact same problem! When you turned off the maf the pcm goes on the secondary table and you are only tuning the primary which will do nothing. Tune the secondary then match it the to primary when you are finished.

[JamesLinder]

If the last two posts did not work, then check your fuel filter; they can become so plugged up that they eventually
ruin your fuel pump. The best way to check fuel pressure is to put a pressure gauge on the fuel rail with a tube long
enough rubber tube to place the gauge near the windshield or lay it inside the car with you and see what happens to
fuel pressure as you drive the car and take the RPM to redline. If pressure drops below 55 psig then your fuel supply
to the fuel rail is not keeping up with what your injectors are trying to deliver. Stock injectors should be fine for your
set up. With MAF unplugged it is indeed true that the PCM uses the secondary table when their is one and an error
code results, however if MAF frequency for an error is set to a value that prevents it from settingan error code when
MAF is unplugged, then not sure if it uses the secondary VE table or not.