20 psi zl1 - ve tune - hitting unknown fuel cut around 3500rpm

[hi_rev_theo]

Hi,

I'm working on a 2015 zl1 with a huge blower that gets 20+psi pretty much immediately. Car is on 2 walbro450 pumps, e85, 102mm tb, id1050's. Tuning in ve mode with hptuners custom os activated. Part throttle is dialed in and car starts and runs great in part throttle but whenever I go to do a full throttle pull, I get a fuel cut around 3500rpm. Richened up ve in boost, and car just runs richer before the cut. Spent hours chasing this issue any help is appreciated.

One thing i noticed is the absolute load pid goes crazy spiking up and down right before cut. But I can't figure out whats making it do it.

Tune and log attached

2015 camaro zl1 20psi custom ve os hptuners forum.hpt2015 camaro zl1 tune2 ve 2 pull with cut.hpl

[hi_rev_theo]

forgot to add... car is making 900+ lbs of tq before cut. I haven't touched the tq tables but I logged fuel and ign tq cuts and I'm not seeing them kick in. Car is a 6-speed manual trans

[dingo16123]

I'm not sure what is causing this, but the timing jump looks just as scary as the fuel! Sorry didn't look at the tune file, since I don't have the latest HPT loaded, but could it be jumping to low octane table which may be higher timing? Perhaps you can knock the 0.74g/cyl airmass portion of the table down to 10ish degrees of timing, and kill any spark adders, until you figure out the fueling. FYI for anyone that doesn't want to look at the log, the cursor is right where the cylinder airmass goes bonkers.

hi_rev_theo.JPG

What is going on at 2700ish rpm on the wideband, circled in red? The O2's don't show a jump in AFR like the wideband. Is an exhaust cutout opening or something?

Any reason you aren't logging injector PW?

[jpierro79]

you dont use both the offset vs press vs ignv and the offset vs volts vs map at the same time. Its contradictory. You use one or the other only. Also ive had better success instead of halving the flow rate and doubling the stoich with halving the ivt. youre better of halving the flow rate and using a 2 multiplier on rate multi vs volts. change your bank1 and bank2 to at least the miniumum of 328 i recommend 400 across with headers. Also you really wont succeed with an sd only on a zl1 of that kind of pressure and fuel flow without maf. I own one i know. Set VVE back stock set maf to stock tune VVE till its starts to overshoot then bring MAF to that RPM overshoot means jumps to 11.1 instead of 11.5 but comes right back 11.5. This will solve your issue. VVE on zl1 uses extremely different predicted coefficients and they will not calculate at 20 psi accurate on sd. Thats also why your VVE is choppy. Please see example of a zl1 on 14 psi VVEIMG_0972.jpg.
The zr1 cant even compute 20 psi accurately. Even new lt4 z06 runs Maf. I highly recommend at your level a holley dominator. As the cyldinder 7 and 8 run about .5 lean and cant be compensated for this. Its WAAAAAAYYYYYYY easier to tune too. Put your maf back in equation youll be fine and timing will come back in. Also stop changing every timing chart. Iat chart and ect together your multiplying on top of each other. I highly suggest against ect chart changing for safety reasons. Start adding the charts and multipliers and next thing you know youve added 12 degrees when you wanted 4

[lukearmstrong1990]

disable fast torque exit and max the torque values