I've got an LT1 with 75lb injectors, a small cam (214/210), and a FAST system. Currently it's idling waaay rich, so that my plugs are fouling ridiculously fast. I just had a shop try and tune it, but they said they leaned it out as far as the computer would let them and it was still running way rich. Now granted this shop doesn't know a ton about tuning (don't have too many options around here, unfortunately).

I don't know much about tuning really either, anyone have any ideas of what might be going on? Does it sound like I might have a bad O2 or bad somethign else? Are my injectors just too big?

I've got to get this car to Vegas (~400mi) for a proper tune, but I need the plugs to last for the trip down.

 

Good god those are huge injectors, maybe they are too large.

 

They are way to big! Do you have any data logs? If so what is the duty cycle running?

 

What type of injectors are they - pintle, disk, ball & seat? Assuming they are they low impedance injectors? Which of your "signature" cars are you talking about? If its the one making 385rwHP, you would be fine with 36#/HR injectors. 75's seems like overkill. Have you programmed the correct flow constant and the correct offsets? Does the flow constant reflect the actual fuel pressure?

I run 78's making 800 HP with a 300shot of dry N2O, and the duty cycle is only 70%.

 

I'm not sure what type they are, how can I tell? These injectors are on the Formula, it's built for around 600rwhp with the turbo (We'll see what she actually makes). I've thought about swapping in the 42lb'ers off the Camaro just for the drive down.

As far as the injector constants, here's the interesting thing: The FAST system has one setting to enter in the size of the injector. I bought the car more or less already built and it had a little time in the hands of a tuner. The injector setting was set at 58ish (don't recall the exact number), which confused me so I tried setting it at 75 but I had to set the boxes in the VE table (it's a SD setup) to around 75-80 at idle to get the A/F reading under 15.

Not sure if I'm giving y'all enough to go on here, I'll see if I can get some datalogs soon. Anyways, I really appreciate the input.