Fuel Pressure Drop - has anyone successfully implemented ADM FPCM on a '14 Chevy SS

[Mach Schnell!]

Schpenxel- is the manifold boost patch the preferred approach? I did some searching after your message the other day and I was unable to find the patch or any instructions of how to implement it. Is there a link to both? Thanks.

[schpenxel]

Should be under the OS menu. It's called manifold vacuum boost or something like that. Have to do a write entire to enable it.

I've never used the SC options so not sure what differences there are vs this way

Obviously fuel delivery issues are #1

[2SS Link]

So my issue ended up being as follows:

My tuner put one of the ID injector data tables (offset v. Volts) into a injecter offset v. voltage modifier. schpenxel found that most lS3 motors have that table set to 1. Because I have varying voltage (not sure why) when the voltage would rise, the engine would go fat (9.9:1) and when voltage would lower the motor would go lean. Whatever the voltage was when the engine was tuned was where everything was set. so when it goes up or down from whatever that was, the injectors would take or add fuel.

I ended up quick fixing by modifying that table to near 1 but it needs to retuned with the entire table set to 1.

[Mach Schnell!]

Should be under the OS menu. It's called manifold vacuum boost or something like that. Have to do a write entire to enable it.

I've never used the SC options so not sure what differences there are vs this way

Obviously fuel delivery issues are #1

Thanks. I am now running the "supercharger fitted" option so am retuning from there. Temporarily running MAF-only tune until I have time to learn the VVE tuning here soon.

[GHuggins]

I tested "Supercharger Fitted" setting at WOT today, albeit carefully with spark advance limited to 10 degrees. Bottom line is that with that parameter enabled, then "Injector Delta Pressure" is approx. equal to "Fuel Pressure SAE" minus MAP boost signal. Of course the "Fuel Pressure SAE" signal drops just the same as before. I have attached (1st) screenshot of my tune file settings on engine/torque management/supercharger tab. I also attached (2nd) screenshot of quick WOT test this morning with time stamp marked at max rpm 2nd gear: SAE Fuel Pressure 41.4 psi, Injector Delta Pressure 34.1 psi, "MAP Stock Boost" (the integrated 3-bar MAP that the PCM sees) 7.9 psi, my secondary MAP sensor 7.3 psi. IFR (Injector Flow Rate), the alarmed red gauge, reads 62.3 lb/hr and IDC (Injector Duty Cycle) 76.6%. AFR 4% too rich Vs 11.4 target.

Compare that to WOT run today with supercharger NOT fitted setting - (3rd) screenshot attached. SAE Fuel Pressure (same) 41.4 psi, Inj Delta Press 43.5 psi (wrong), IFR 68 lb/hr (same), Inj Duty Cycle 70.6. AFR ~ 2% rich. Higher MAF signal than "superchargerfitted" tune run.

So the "supercharger fitted" setting works to reference boost, but of course does nothing to compensate the inadequate fuel pressure at high flow rate. And since I have my tune roughly dialed in for the non-MAP-referenced Inj Delta Pressure, changing to a method that references MAP under boost, such as by using this "supercharger fitted" setting, would require some tweaking.Attachment 62060Attachment 62061Attachment 62062

This is interesting - I was always lead to believe that albeit the switch was enabled - it wouldn't actually do anything because the physical internals of the ecm's were different - thus - no outputs...

[Mach Schnell!]

I finally swapped out the factory FPCM with the ADM-programmed FPCM, which allows setting 3 fuel pressure setpoints that are selected based on fuel flow rate (no 400kPa upper limit). My understanding is that this FPCM has the same functionality as the ZL1's. [My car, a 2014 Chevy SS LS3 with Whipple @8psi, supposedly comes with the ZL1 fuel pump but NOT the ZL1 FPCM]. I have attached 3 screenshots from hptuners log. (1) File "20160803 tune01L before 3-bar factory map, delta-pressure injector flow control and ADM FPCM" was my starting point that still used factory stock 1.2 bar MAP sensor, (2) "20160903 tune04D after 3-bar factory MAP and delta-press Injector flow control, before ADM FPCM" with the proper ZL1 3-bar MAP sensor and "supercharger fitted" option selected such that "Injector Delta Pressure" now reads proper pressure drop across injector, and (3) "20160909 tune05G1 after 3-bar factory MAP, delta-press Injector flow control, ADM FPCM" after new FPCM and proper programming. In each case I retuned (MAF-only, using LTFT closed loop for part throttle, WB AFR open loop for WOT). On the display, the upper-left large round gauge is aftermarket MAP, to the right of it is factory MAP (1.2-bar in pic 1, 3-bar in pics 2 and 3) both measuring manifold pressure below sc intercooler brick, and directly below those gauges are SAE fuel pressure and injector delta pressure. Case 1 and case 2 fuel pressure setpoint is fixed at 400kPa (58psi), while in case 3 w/ new FPCM fuel pressure is set at 400kPa for "low" flow, 415 kPa for "normal" flow and 460 kPa for "high" flow. FPCM voltage ("fuel system min voltage" setting was 14.5V in case 1,2, and 15.5V in case 3. In previous tests running case 1 conditions, FPCM voltage selection didn't have significant effect on fuel pressure drop.

Results:
In case 1, at peak hp and indicated 7.7/2.9 psi boost, the SAE fuel pressure drops to 38.4 psi, and the injector delta pressure erroneously reads 43.5 psi due to saturated MAP (and incorrect ECM delta-P calc). In case 2, at peak hp and indicated 8.3/7.7 psi boost, the SAE fuel pressure drops to 40.6 psi, and the injector delta pressure reads 33.8 psi, about right for the boost level. Finally in case 3, at peak hp and indicated 8.3/8.3 psi boost, the SAE fuel pressure drops to 53.2 psi, and the injector delta pressure reads 42.9 psi. 20160803 tune01L before 3-bar factory map, delta-pressure injector flow control and ADM FPCM .jpg20160903 tune04D after 3-bar factory MAP and delta-press Injector flow control, before ADM FPCM.jpg20160909 tune05G1 after 3-bar factory MAP, delta-press Injector flow control, ADM FPCM.jpg

[GHuggins]

So it was better then with the different FPCM or not until you did some other stuff?

[realsquash]

What did you change in the tune between runs 2 and 3?

[Mach Schnell!]

The FPCM was changed last, and it allowed me to increase the fuel pressure, which was my goal. I also wasn't satisfied with the "hokey" way injector duty cycle was selected by ECM without it knowing injector delta-P, due to factory 1.2 bar MAP sensor. For a given target AFR, the actual AFR always increased as rpm and load (flow rate) increased. This first thing I changed was to replace the factory 1.2 bar --> 3 bar MAP sensor so that I wouldn't tune "blindly" and so the fuel injector (delta) pressure drop Vs flow transfer function could be properly utilized. But the ECM algorithm doesn't use the manifold pressure once in boost unless its told. I selected the "supercharger fitted" option which told the ECM to reference MAP both in vacuum and in boost to calculate delta-P across injector and obtain flow rate. So with the proper sensor and "supercharger fitted" option I had to retune (adjust MAF) and AFR was more stable across operating range. I then tried increasing FPCM voltage to drive fuel pump harder but didn't achieve significant difference in fuel pressure. Finally I changed FPCM which allowed me to increase fuel pressure at higher flow rate. There is still a large pressure difference between setpoint and actual fuel pressure, but it is very repeatable, and fuel pressure is 10 psi higher than with stock FPCM and single 400kPa (58psi) setpoint. I had to retune (MAF) for operating over a new, higher pressure portion of the injector fuel pressure Vs flow curve. Overall I am satisfied with the result.

I am at 53 psi SAE fuel pressure at 6K rpm and 66.x% injector duty cycle with kit's 63 lb/hour injectors

[Mach Schnell!]

Realsquash - I had to bump up the MAP curve at lower range (3000-6000Hz, especially at lowest end) and also in 8000-10000Hz range. This was all using LTFT closed loop tuning. The adjustment at high end, over the 10KHz-12kHz range, using wideband AR error @ WOT open loop, was small, about 0.5%.

[realsquash]

Ken - just humor me here - set all the flow modes to 58psi in your tune and go out for a rip, with the new FPCM installed. Then see what the fuel pressure does.

[Mach Schnell!]

Ken - just humor me here - set all the flow modes to 58psi in your tune and go out for a rip, with the new FPCM installed. Then see what the fuel pressure does.

Realsquash - OK I will have to try that. By the way, I originally tried to set up the ADM FPCM like the CTS-V's 3 pressures, with the low flow region at 350kPa setpoint. With my injectors this didn't produce stable operation or repeatable results - so I couldn't calibrate. Moving the low pressure setting back up to 400 kPa (58 psi) fixed that.