Wot to lean, can I tweak pe enrich to fix this?

[04colyZQ8]

My ltft are on average -.08 to -3.9 not to bad, idle, mid range it pulls good feels good, idles so smooth!

My commanded pe for gas, and alcohol are set at 12.3:1 from 1200-3500rpm and from 12.8:1 from 3600-5500 rpm. And 12.98:1 from 5500-6600rpm

Yesterday my wide band read close to those numbers, and truck felt good no knock! Today it ran 13.3-13.5:1 and knock retard real bad!! What gives?

I can tweak my upper maf hz, but then mid and part throttle will suffer!

Is it bad to scew my pe on purpose? So maybe run a graph for pe biased on commander afr, verses wide band error?

[SultanHassanMasTuning]

check your fuel pressure

[04colyZQ8]

How? Mechanical gauge? There isn't any fuel pressure sensor on this truck. Not sure I like the idea of a gauge pooping through the good at 120mph?

[5FDP]

Yes, with a mechanical gauge. Get a long enough hose and tape it to the windshield.

You don't have to be going 120mph to see a fuel pressure drop. If it goes from 58 psi to 50 or lower in a quick pull, you know you have a problem.

[boostbuick]

yea as 5FDP said check fuel pressure or regulator sounds like its loosing it upper rpms and when u restart it the open loop is doing some changes until up to operating temp but id get the fuel system fixed to run more cfm and keep the 58 psi for good running engine let up know what u find out

[mcfarlnd]

Is it a NNBS 07+(non-classic) truck??? If so, you definitely have a pressure sensor.