Ignition timing for Hydrogen based fuel

[Wiz007]

Hi guys,

I am totally new here and have no past experience with tuning so please bear with me. What I want to do is to set the ignition timing to 20 degrees ATDC. The reason I want to do this is to be able to use hydrogen based fuel like the output of an electrolyser cell. I looked at the demo version of VCM suite and it has many windows to set the timing advance and retard. But here I do not need to advance or retard (at least initially) but set static ignition timing to 20 degrees after the piston cross the top position. Because hydrogen burns so fast, the spark has to occur after TDC. Does the VCM editor allows to set the ignition timing in such a way? Can I also turn off the fuel injectors via some settings in VCM? because the hydrogen will be just mixed with air at the engine air intake so no need to use the injectors. My goal is to power the electrolyser with a separate battery and use the output gas as fuel and potentially get few hours of drive time. The power to the electrolyser (and hence the amount of H2) can be pwm controlled based on the accelerator position and engine load, which I think can be easily read from the j1939 CAN bus. Thanks in advance.

[Montecarlodrag]

The editor lets you change the timing advance for all the existing tables in the PCM's calibration.
However, some PCMs have a limit on how much the timing can be retarded. Which year/model is your PCM/ECU?

[Wiz007]

Thanks so much for your reply. Well I was going to buy a used car to do the experiments. Can you recommend some make & model that are the easiest to work with and allow unorthodox ignition timing?

[Wiz007]

Is there a document that list step by step instruction to reflash the spark tables using VCM? don't want to brick the ECU in my 15 suburban. Also, is there a way to test the new tables without reflashing the ECU?

[MikeOD]

You're not going to brick the ECM if you just flash "calibration only". No numbers you put in the tables could brick it.