Tuning question

[doommachine]

OK, so I have recently installed an AFPR.. and I have been attempting to tune the car at idle (the car drives almost the same, actually slightly better/not as rich when cold). My base fuel pressure is 38 psi.

Anyway, I am having a weird issue that I am having difficulty working out - there is a point where the car is happy to idle at 8-900 rpm, however that point is nearly too rich for the 02 sensor (between 980-1000mv). The timing at idle is set to 6 degrees, when it was set to 10 there was visible black smoke from the exhaust. It is MUCH happier at 6 degrees.

However, it is still way richer than it used to be. Theres a point when I start leaning it out that the idle goes up to 1500 rpm, and is stable, if I take it down another point it starts pulsing horribly up and down between 12-1500 rpm, then it stalls. I can't lower the idle any further, the idle screw is all the way in, and I have cleaned the throttle body.

I guess my question is what should I be aiming for, should I be looking for vacuum leaks post throttle body and try to get the idle down from when it goes up to 1500rpm, or is it more likely to be a fuel delivery issue, ie the fuel pressure is too low/high to get accurate injection at idle. I'm running evo8 injectors.

 

[Jayz-1]

What computer do you have for making the adjustments?
Is it a wide band oxy? or the narrowband stock item?

Fuel pressure is fine for idel, as long as you can lower the injector pulse to get the mixtures right with the bigger injsctors.

Thank you
Jason

 

[doommachine]

I have a haltech E6K. The injectors aren't particularly huge, so I dunno, I guess I'm thinking that there is some sort of vacuum leak, the car does feel like it bogs down when I add enough fuel to make the idle lower... where could it be leaking post throttle body? I guess I'll check all the vacuum lines etc.