Help Tuning W/fuel Pressure

[sweet97]

I have a '93AWD. Equiptment is a 50 trim, 660 inj's, CAI, mandrel exhaust and a GM MAF-Translator. I have a wideband a/f meter, scanmaster. I have it tuned for 20 PSI, no knock and 23 degrees of timing. It is running a bit richer under WOT than is best for optimum power. I do not want to lean it with the translator as that would give me more timing. I have my base fuel pressure set at 40 psi with the vac. line off. How low have you gone with your base fuel pressure? I was going to go to 35 psi with the line off but could I go lower without adverse affects on the aspects of the car's running?
The motor likes a 10.5-10.9:1 a/f and now under WOT it will go to a 10:1 or sometimes lower. I need to run it leaner without adding timing. Suggestions wih my present equiptment please! Mark

 

[trbotaln]

Well you could lean it out and set the base timing lower.

 

[sweet97]

Well, I've got my base timing at 2 degrees now. Since I am in central, N.Y. I will cover the car and wait until spring. I think I will bring the timing back to spec and start from there. On a run today I got my timing at 15 degrees which makes more sense. I did back the fuel pressure to 30 with the line on. Some rich sputter at high rpm's backed up by the wideband reading rich for my motor's liking. I still have to do the fine tuning WOT tning on the MAFT which at 2% increments could be the solution as I can lean it out at 2% instead of the regular 5% increments the MAFT has. At any rate the car is running strong. Do some of you guys with 1g's run with some knock, like 10 counts or zero all the way?
I have a 2.5" ss mandrel exhaust I bought for my EVO and now I need a 3" system so I am selling the 2.5". Does backpressure play into this tunig at all? Mark

 

[BrokenTsi]

im from cny as well. I run with some knock, maybe 5 counts as most. I got pretty much the same setup as you except my 50 trim is comin in the mail soon. I run about 3 btdc with stock fuel pressure. Look into getting a keydiver chip. I just picked up an eprom ecu for my 90 and tuning will be much easier I hope.

 

[sweet97]

Finding a GOOD EPROM ECU is the problem! mark

 

[pneumo]

Here's what I'd do. Check your injector D/C, then lower your base pressure until you are seeing close to 90% to 95% DC while still maintaining your A/F ratio. Don't lower FP so much you have to use over 95% DC because the injectors tend to loose accuracy around that point and above.