Dan Hill

I just finished my turbo project and am starting the tuning process now. I have a couple of questions for anyone who has similar setup.

What I have on the car:B16a, T3/T4 new, egt, af gauge, matched 450's, fpr at 48psi, current v-afc setting at rpm of question -38.

1) If I slowly rev to about 1700 rpm, the motor sort of pulses and the af meter jumps from rich to lean with each pulse. What is that? EGT values are around the 1100 F and steady.

2) Off trottle the injectors seem a little harsh and abrupt at less than 1/3 trottle applications. Is there a way to smooth this out?

3) What fuel pressure are you using with the 450 injectors?

Thanks,
Dan

Joseph Davis

1) It's called closed loop... I've seen engines that pulse like that on very light throttle in neutral, 'm guessing that your O2 sensor is a bit lazy and is switching slowly enough that the rich/lean mixture variation ossociated with closed loop is causing the hunting tach.

2) What do you mean the injectors seem harsh off throttle? If you are talking about bucking, it's ignition related.

3) Stock.

Don't run much boost, your ignition timing is jacked forward from stock.

Dan Hill

I have retarted the timing 12 degrees. I don't mean bad off trottle, but it is just a little more off/on than it was before. Sorry it is hard to explain "feel".

Thanks for the O2 sensor tip.

I raised fuel pressure, because it was a little lean at the very top of the rpm band and I was at -28 on the afc. Raising the fuel pressure richened it up smoothed it out.