GM gen 4 FPCM dump request OS 23482558

[hjtrbo]

Hi all, wondering if anyone has a full read of a gm fuel pump control module?
FSCM F, FSCM, 2015+ Camaro Z28/SS/ZL1
OS 23482558
The bin I have only has the cal & diag segments present starting at 0x7c0000. Any help is appreciated.

[kur4o]

I have an idea how to get a full dump, but it will require a module, factory flash, patched OS, and some time figuring addresses.
Hope CPU is ppc or we are doomed.

[hjtrbo]

The S/W I'm using only writes the cal & diag segments. No reading is supported. The attached bin does not disassemble with the processor option set to powerpc BE 32bit.

[kur4o]

Code: Select all

@7f5062
00 78 00 00- 00 78 FF FF
00 79 00 00- 00 79 FF FF 
00 7A C0 00- 00 7A DF FF 
00 7A E0 00- 00 7B 7F FF 
00 7D 00 00- 00 7F 43 FF 
00 7F 50 00- 00 7F 7F FF

This is the OS part, Try bruteforcing diss out of it using all known cpus

[hjtrbo]

Thanks, getting some hits on HCS-12X:BE:24:default. Fingers crossed

[Tre-Cool]

hj have you got access to a real module.

pretty sure i got a module on the shelf in the workshop.. somewhere...

[hjtrbo]

The only module I have is in the car. Good news, the processor settings mentioned above have decompiled it cleanly.

Next target is trying to locate where the fuel pressure broadcast packet is formed and work back from there. This stupid module is modelling the fuel line pressure drop. Fine for standard cars but no good for modified. The reported pressure drops off quite a bit as rpm increases. I know that's bullshit as i've got twin staged 460's in the fuel bucket which is plenty for my power level. A mechanical gauge reads as expected and logging fuel pressure sensor volts and applying the transform reads the same as the mechanical gauge. I'm hoping to find a switch I can flick to turn off fuel line pressure drop modelling.

The reason for wanting to turn off the fuel line pressure drop modelling is to have accurate fuel pressure reported to the ecm. Currently my pressure delta IFR table is flatlined. That is normal for most people on a referenced FPR return setup, however I want to enter the IFR's as per the injector data. By doing this, if the secondary pump goes bad, blocking filter or any other thing the ecm will see the lower rail pressure and compensate accordingly. My canbus gauge will alarm to low fuel pressure / high duty cycle early into a pull so I'm made aware of a problem and can back out before the afr's go lean.

[kur4o]

some files to get you started.


https://www.nxp.com/design/design-cente ... :CW-HCS12X

[hjtrbo]

Found it. There is a pressure droop vs fuel flow compensation table at address 0x7c2cd2. When overlaid with previous datalogs there is an extremely strong corelation. At full fuel flow its trimming 7.5psi off the reported signal. I'll zero out the table and see what it does.

[Tre-Cool]

why the hell would they have that in there if it has an actual sensor to monitor pressure.

Coincidentally i had a VF GTS on the dyno yesterday fuel pressure went from 58psi upto 4k rpm all the way to 38psi by 6800rpm.
Has Cam & 14psi so i'm believing that it's out of pump, I dont think they are as good as a single 450 TI pump?