Modding Vy Factory LPG

[Nathen]

I am messing about wit a VY factory LPG PCM. I would like to figure out how to get the PCM to issue the code over the Bus to switch the Cluster from LPG to Petrol and via versa.
What I have discovered so Far
PVM Pin out (easy Bit) for LPG
X2 Pin F16 Power on all the time
X1 pin A3 PCM output. Grounds to turn on the tank Valve and Regulator Valve
X3 Pin E16 PCM Output to Fuel control valve. Looks like this is just pulses off and on to control the vacuum on the regulator. The FCV is the same valve that is used for the evaporative canister control.
X3 pin F4in a switched input to swap between LPG and Petrol.
The PCM is not special. I flashed the Bin into a PCM I got from the wreckers and it worked perfectly.
The PCM issues a code to the Custer to change fro LPG fuel gauge ect to Petrol. See the 59(petrol) or 5A (LPG)in at the end of the string below

17:16:01.296 Rx'd Frame = 41, 68, 12, 0, 0, 0, 33, 33, 0, 0, 70, F0, 15, 0, 0, 11, 0, 0, 0, 0, 0, 59,
17:16:00.875 Rx'd Frame = 41, 68, 12, 0, 0, 0, 33, 33, 0, 0, 70, F0, 15, 0, 0, 10, 0, 0, 0, 0, 0, 5A,
The ignition map has been identified by others in the BIN
What I think I Know.
The PCM turns the petrol injectors off (not the fuel Pump) when on LPG (Im still working on confirming this)
The PCM adds petrol when starting cold
The PCM adds petrol under hard acceleration/Possibly High RPM

I have compared "cleared" Bins to identify the extra data for the LPG control, But that is where I become stuck.
I will be adding injected LPG using the old tank. So my ideal end point would be using the PCM input to control the cluster for LPG level, Tank valves and ignition map. The petrol Injector circuit would stay live because I understand this how the LPG injectors are driven with the aid of a software box

To start I would like to identify the extra maps in the PCM. There must be something for the FCV, Petrol injector under the conditions described above
I would appreciate any help with the best way to identify maps in the PCM.
Thanks

[yoda69]

What you’ve got is fairly right.
There is an extra wire from the LPG fuel sender to the instrument cluster that needs to be fitted and the instrument cluster reconfigured to recognise the the message from the PCM identifying what fuel it is running over the ALDL. messages.
When running on LPG the fuel pump will be disabled unless required, ie. cold start and high speed &lad running (VSR-valve seat recession protection)
There are no LPG injectors on the VY, it is an old school system dumping gas into the intake between the MAF and throttlebody. This is why traction control can not be used on gas.
There are separate maps for spark when running on petrol and lpg, and also some control for the FCV.

If you’re running injected gas you’ll need to keep the vehicle think it is running on petrol or you’ll get no signal to the injectors. This is where the injector module is needed to convince the PCM everything is ok.

Hope this helps.

[Nathen]

Thanks I had sussed the clusters out including the extra wire and setting the hex in table 6 to enable the LPG fuel input. I have a donor VY with Lpg that was running quite happily until some A888888 decide to try and drive in my lane.
I just want to move away from the Carburetor style because they restrict the engine to much.
So I have a whole system to mess with. What I am really interested in is decoding the PCM a bit more, In particular the ADL messaging from the PCM.
So any advice on locating maps, or pointers to information on this subject would be appreciated.

[pman92]

The BCM sends out chatter request messages to all modules that then respond with data every 128ms. Message 0x40 is PCM request.
The PCM responds with a message 0x41. This contains a heap of engine data, coolant temperature, warning light status etc. The cluster reads this and usesit to operate the temperature gauge and engine warning lights.

I beleive part of that message 0x41 packet is fuel type (petrol/lpg). Is it possible the cluster turns the lpg light on from that data instead of a seperate wire?

If so you would have to have the PCM thinking it's on LPG to send the correct data to bring the LPG light on. But in that case it would also disable fuel injectors

[Nathen]

Thanks you have put another part of the puzzle together for me. I had worked out that the 59 and 5A on the end of the message was petrol and LPG. I did this by listening to the messages and seeing what the consistent difference was when i switched between petrol and LPG. I had tried to spoof the cluster but had been unsuccessful. I would have to read the BCM message and spoof the response. The wire to switch to LPG defiantly goes to the PCM, hence I was hopping to mod the factory bin.

[pman92]

The 59 and 5A you are looking at is the checksum on the end of the packet (5A is one more than 59 in hex)

The different byte is 6 bytes from the end of the packet (10 or 11 in your example in first post)

By trying to spoof the cluster by incorrectly changing the checksum you would of got no result because the cluster would of rejected the data due to invalid checksum.

Try again by changing the 10/11 byte. It is only 1 bit that is changing (the least significant bit). You will probably find this will operate the light as you intend.
YOU WILL HAVE TO RECALCULATE THE CHECKSUM or just send the example packets you found in your first post that already has it recalculated.

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For future reference with ALDL data:
- The first byte is device ID / packet ID (what the packet is)
- The second byte is Datalength (how long its payload is, with an offset of 0x55)
- The very last byte is checksum (it should be calculated from all other bytes in the packet)

You can also search and find the tunerpro ADX files by VL400 for his ALDL logger. They included definitions of the chatter data (Definition of what most of the other stuff is in message 41)

[pman92]

The major problem I see you having is if you tell the PCM it's on LPG, your LPG light and gauge and ignition map and everything will work. BUT it will turn the petrol injectors off. And your injected LPG system probably needs the injector pulse to calculate it's LPG injection pulse?

[Nathen]

Yes you are 100% correct. What I would like to have is at min the factory computer drive the ALDL message to switch the cluster to LPG. Ideally i would like to use the factory spark tables and outputs to switch the system on. However the LPG computer drives the LPG injectors from the petrol injectors so they need to stay operational.