Help, do I need bigger injectors?
Thread Starter
Teching In
Joined: Nov 2002
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From: South Florida
Help, do I need bigger injectors? 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!
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!
TECH Resident
Joined: Jan 2002
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From: USA
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.
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.
Thread Starter
Teching In
Joined: Nov 2002
Posts: 46
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From: South Florida
Originally Posted by Team ZR-1
You DO need the larger injectors and simple math shows the stock ones are at 100% duty cycle by 354 HP.
TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
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.
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.
