aram

iTrader: (7)

I for some reason am having problems with high injector duty cycle on my car and I know I shouldn't be.

All I have is a stock 2000 LS1 in my RX7 with:

JBA Shorties
4L60E w/ TCI 4000 Stall
Gutted stock cats
Custom 2.5 to 3" Y w/ 3" Catback
Custom CAI tube
Ported Stock TB
LS6 Intake
ASP Pulley
2001 Fuel Injectors (28.8 #)
2001 PCM
Walbro 255 LPH Fuel Pump Rewired with heavy gauge wire directly to pump
Stock Corvette Regulator at 58 psi constant, fuel pressure doesn't drop
-6 Line return and feed
Stock Cam, Stock unported heads

I get about 95% DC at WOT at 6000 rpm with the new injectors (before had 26# stock injectors). Before I was seeing 99% DC at WOT. The pulsewidths are 19.5 or so IIRC. I was hoping the new injectors would drop the DC to at least 8x % DC. I don't see any KR at WOT and the O2's stay fine. I wanted to eventually run a 75-100 hp dry shot or add a pretty big cam but don't feel comfortable with the duty cycles so high.

I only dynoed 302 RWHP recently on a dynojet dyno (unlocked through IRS).

I don't understand how the DC can be so high.. the air fuel ratio wasn't that rich.. low 12's on the dyno. My friend even leaned out the PE enrichment to pull the WOT air fuel down because it was running too rich on a stock tune.

I have heard of 400rwhp through stock injectors and I'm not even close.. in a M6 the car might dyno 340 or so but that still isn't close. I know I can get bigger injectors and it looks like I will but I just don't see why I need to without the power required for them.

Forced370GTO

first of all, why are you running that low of an a/f ratio? you realize it will be richer on the street then on the dyno right? i would have tuned my a/f at WOT to be somewhere near 13.0/1... just my .02

aram

iTrader: (7)

I know the air fuel is rich right now but that is with us leaning the car out already off the stock tune where it was commanding 11.x:1.. we changed the commanded AFR to 12.6 or so I believe. Also remember that my car has a raceweight of less than 2900 #'s so the load is not as great as a 3700 # raceweight fbody does so the air fuel doesn't change as much. It still shouldn't be maxing the injectors like it is though.

aram

iTrader: (7)

I just bought 12 stock GTP injectors that are supposedly ~39.5 # injectors at 58psi so those should help.

Bombguy99z28

God doesn't like RX-7s, didn't you know?

SRPerformance

Did you reset the IFR (above) in the PCM when you changed the injectors?

to something like: 28.15047 28.5845129.20456 30.7547 31.12673 31.62278 31.99481 32.18082 32.36684 32.67687 32.86288 33.23492 33.79297 34.35101 35.09508 35.90115 36.76923

Bombguy99z28

Yeah, IFR was changed.

FYI, I don't know about you, but I wouldn't run 13.0 AFR if I was planning to do a 100 dry shot. But hey, if you do that with your engine thats your business.

SRPerformance

With 28lbs injectors they max out after 350rwhp but I have seen them go over 400rwhp. Are your fuel filters blocked, were the injectors second hand?

SRPerformance

re-reading the thread, if you are getting DC off 95% with 28lbs than that would be right as at above 350rwhp they will go 100%.

aram

iTrader: (7)

That sucks. I always thought they were good for more. I only dyno'd around 300rwhp but it was unlocked through a 4000 stall and IRS so it probably would look a lot healthier through a T56.

I don't think there is any fuel restriction.. i got the injectors as take offs from a car and they were low mileage and were good when pulled. The fuel system is a little bit healthier than a stock LS1 fuel system. I just replaced the fuel filter/regulator/pump (walbro 255) about 3000 miles ago.

I guess I'll try out the GTP injectors and see what they will do.