Im sure you all know me by now. I have a 99 LD9 with the M45 and lately Ive been trying to tune the fuel as efficient as I can with the fmu; but im running into a few problems (HPT will come later).
I got my wideband (LC1) installed and thankfully it was flawless. I started the car, waited for the 02 sensor to warm up and got a reading of 9.7 to 1. Once the car was fully warmed up it read about 10 to 10.2. Now I also have the Cartech BEGI FMU and after I turned the onset screw counter clockwise for about to complete rotations (which I presume changes my idle air pressure; correct me if im wrong) nothing changed on the reading. So Im kinda skeptic, do I need to get an AFR? I thought the BEGI 2025 could control the Air/Fuel at idle.
I didnt get a chance to see the reading in boost because my labtop died but hopefully ill have it tomorrow and share with you guys.
The Wideband is the Innovative LC1
My injectors are 310CC; would the injectors alone make the car idle at 9.7 or does my fmu control that to with the onset screw. Im aware that the needle valve on the BEGI controls fuel in boost but dont really understand the function of the onset if its not to control idle pressure.
To set the FMU base pressure (at 0psi) or atmospheric pressure) follow this:
Quote:
The first adjustment is of fuel pressure is at the atmospheric pressure point, and can best be done at idle. To simulate passing through the zero point, the vacuum line must be removed from the our FPR. The FPR then sees atmospheric pressure as a signal, same as zero on the boost gauge. Control of the fuel pressure at the zero point is by the Allen screw in the center of the FPR. Clockwise on the screw will raise the pressure. Once adjusted, plug the vacuum line back onto the FPR and observe the fuel pressure drop to the stock figure. A suggested pressure for starters is 48 to 50 psi.
Please understand, this will vary from engine to engine, and is not a magic number. The “magic” number is whatever pressure your vehicle requires to pass thru the boost onset without the lean flat spot. It is not unusual to see pressure anywhere from 40 psi to 55 psi. Use whatever works best.
from what we figured out, stock is 60psi @ 0psi, and 43psi @ (-20vac)
his injectors are 310cc / 240 cc so we want 75% of stock fuel pressure
60psi x 75% = 45psi @ 0psi
43psi x 75% = 31psi @ (-20vac)
So you want you Begi set to 45psi @ 0 psi (vacumm signal unplugged)
then you need to adjust the rate of rise (3:1 4:1 5:1 6:1) whichever you need for running boost.
if you were to use 5:1 (5psi fuel pressure for 1 psi boost) at 5psi boost pressure you will increase 5x5 = 25psi total fuel pressure.
(base @ 0psi) + (gain from fmu @ 5psi) = WOT @ 5psi boost pressure
45psi + 25psi - 70psi fuel pressure at 5 psi boost.
keep in mind the second number can be changed by adjusting the needle valve in or out. Make sure you get it tuned with a wideband on a dyno, and you are good to go. 12:1 is as lean as you want to go, some will say 11.5:1 is the magic number on 2.4 Ld9 engines.
About that rich running at idle you need the pressure in your rail to be 31psi with your injectors to obtain "stock like" values.
HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED
Thanks for walking me through it on msn bro...gotta get that AFPR asap, but at least im a bit more confident in boost with the wideband. For now we got the fuel pressure reading 43 without the signal line plugged in and 0psi when its plugged.
The AFR like that is 9.8 at idle. Since it only deals with base line I'll just leave it like that till I get the AFPR and lower it to 70% of the stock FPR.
