dmtnt

Car is an '02 Z06 with only an intake and LS1Edit tuning. What I've done so far is scale the IFR table by 85% to get my ltrim's negative, raised the threshold for COT, and scaled PE vs. RPM by 98%. Haven't dyno'd with a wideband yet, but WOT my O2's read between .880-.890 as they should. However at WOT at top RPM's, my injector duty cycle is showing 100%! I know the rule is above 80% its time to upgrade, but I find it difficult to believe that I need bigger injectors on an almost stock car. I have long tube headers on the way and don't want to make matters worse. I get some knock retard, but always at mid-RPMs and 1/2-3/4 throttle, none whatsoever at WOT and high RPM's. I've double-checked for air intake leaks, etc to make sure that isn't the culprit and there aren't any.

Should I try returning to stock tune and check the IDC? Stupidly, I didn't log any WOT with the stock tune. If I do opt for bigger injectors should I go 30# or 32#? Since I had to reduce IFR by 15% to get the ltrim's negative, increasing the injector size by 15% would yield a 32# injector (stock Z06 is 28#).

I'm just really confused because guys are making big hp with stock injectors and my mods don't warrant it yet. Maybe I have fuel pressure issues?? Anything else I should check?

Thanks!

ataylors

iTrader: (2)

when in doubt put it back to stock and start from there. You shouldnt need injectors.

Team ZR-1

You DO need the larger injectors and simple math shows the stock ones are at 100% duty cycle by 354 HP.
I have tuned well over 250 C5s and time and time again when the SVO 30s were installed all the knock issues and lower PE/WOT timing were tuned out.
Ask yourself why the C5R uses 44 lb injectors and your engine only has 28 lbs.
The using larger injectors when tuned correctly and you end up with better performance, smoother running engine and better gas mileage.

Your peaking 100% duty cycle yet tuning them to go richer when they cannot flow any more.

dmtnt

Thank you Team ZR-1, I was hoping you'd chime in here. I've ordered SVO 30#'s and will adjust the IFR accordingly (I know they are actually 36.12# at 58psi). Do you suggest any modifications to the injector offset table? Most threads say no.

Team ZR-1

No leave the offset voltage alone, it works just fine with just adjusting the injector flow table. I've monitored SVO 30's put in 3 years ago and they still are fine
You also get a biproduct in using the larger injector for the stock injector had to have longer On times ( pulse width) and thus the injector coil was on longer, more current draw on PCM, coil heating up injector and more load on PCM hardware supplying the circuit to the injectors.