silversweetZ

iTrader: (11)

Hey guys, going to the tuner this afternoon. I have a Incon twin turbo setup running SD 80lb injectors with a aeromotive fpr. What is a good fuel pressure to start at? right now I'm at 60psi on a base tune and AFR's are in the high 10's with a twin walbro 255 with the second pump on a 4psi hobbs switch. I keep reading base pressure, is that fuel pressure at idle? Any assistance is appreciated!

silversweetZ

iTrader: (11)

So what I'm gathering is fuel pressure at idle should be 43.5 psi and my FPR should raise the fuel pressure 1 psi for every psi of boost....does this sound correct?

silversweetZ

iTrader: (11)

So I tried adjusting the FPR down to 43psi. Won't go below 58psi. Dual Walbro setup using stock lines with the evap setup as return on stock fuel rails. Can someone chime in and tell me why I can't get it below 58?

Krom

either your regulator or return line wont flow enough fuel back to the tank

silversweetZ

iTrader: (11)

Finally got it figured out, I never pulled the regulator from the fuel bucket. Pulled that and we got it to 43psi. But here's the issue now. It idles super fat at 11.0 with it fully commanded at the lowest pulse width. He suggested to bring the timing down to 13-14 degrees at idle and that got the AFR to 14.7 but I'm wondering if its ok to just leave it at 11?

Setup
2002 5.3 on a 2 bar speed density tune
2002 Z06 cam
Siemen Deka 80lb injectors
twin walbro in tank with 2nd pump on 4psi Hobbs switch.

stevieturbo

Fuel pressure can be whatever you want it to be.

And base pressure is fuel pressure with no vac applied.

As for mixtures after pressure etc has been set, you need the car tuned now.

silversweetZ

iTrader: (11)

Car is at tuner. Were just having a hard time getting the idle AFR correct. With the Siemens Deka 80lb injectors we commanded min pulse width and were still getting 10.8 AFR at idle. But we got it figured out. I appreciate the help!

cmiller8006

iTrader: (1)

As stated make sure the pressure is set with no vacuum on the regulator. I initially did that and set mine to 60 and was really running 68lbs base.

Old Geezer

iTrader: (3)

" But we got it figured out."...And, that is??

kingtal0n

iTrader: (1)

You need to get the idle at least to 14.2:1 if you plan to keep the plugs clean and reliable for a daily driver. any richer than this and they will slowly soot up (cover with black carbon compound) and this goes double for all the parts in your engine, i.e.. your pistons/valves/ports will all slowly fill with a carbon coating due to excessive fuel.

Also, the excess fuel will help "wash" the oil from the cylinder walls. Brief exposure to this situation during WOT is acceptable; prolonged exposure to this situaiton (such as during idle) may result with excessive wear and tear on your engine, and dilute your engine oil with gasoline faster (it will always dilute slowly due to the nature of the engine, but having a rich idle will dramatically speed this process up).

silversweetZ

iTrader: (11)

Retarded timing at 900 RPM and below to 12*. We get a smooth idle at 14.6 AFR.