Autosport Labs

Can someone help me understand the fuel level that my MK3 is reading. E46 M3, 63L/16.6gal tank. When reading the CAN via the BMW INPA software it shows 57 liters(says gallon though). The RC is showing a value of 28. I'm wondering if it's reporting only one of the level senders. The M3 has two senders due to the saddle type fuel tank. I attached the INPA screen if anyone wants to help me figure this out. I may just be out of luck with monitoring the fuel level. I was hoping this worked show we could monitor fuel level via the telemetry during endurance races (not sure that's even possible yet).

Thanks in advance.

BK wrote:Can someone help me understand the fuel level that my MK3 is reading. E46 M3, 63L/16.6gal tank. When reading the CAN via the BMW INPA software it shows 57 liters(says gallon though). The RC is showing a value of 28. I'm wondering if it's reporting only one of the level senders. The M3 has two senders due to the saddle type fuel tank. I attached the INPA screen if anyone wants to help me figure this out. I may just be out of luck with monitoring the fuel level. I was hoping this worked show we could monitor fuel level via the telemetry during endurance races (not sure that's even possible yet).

Thanks in advance.

I don't know anything about the specific RCP E46 CAN Mapping or how it was derived. However I suspect the mapping is reverse engineered and a mistake was made in the value mapping equation. Take this suggestion with the appropriate caution.

I notice that the RCP reading (of 28) is almost exactly 1/2 of the INAP tank reading (of 57). Also the RCP value is not very close to either of the individual (left/right) INAP sensor values. This leads me to suspect that the RCP mapping is incorrect and need to be multiplied by a factor of two.

This could be verified by looking at the reported RCP values at different tank levels to see if its consistently off by a factor of two.

John
Schumacher Taxi #189

Good observation. I was wondering if the RC was averaging the two 'lever type sensor' values. I'll have to monitor it and then make up a formula to compensate for the readings.

Thanks.

BK - were you successful in resolving this? I have a non-M E46 and the preset decodes to 28L with a full tank for me too, hoping there is an answer out there somewhere for this item.

jwads wrote:BK - were you successful in resolving this? I have a non-M E46 and the preset decodes to 28L with a full tank for me too, hoping there is an answer out there somewhere for this item.

I ended up adding to the fuel level can mapping a formula multiplying by 2, and then applying the L to G conversion. It logically should work but I have not tested enough different fuel levels to be sure.

Has anyone confirmed that this is working? (ie just multiplying the Fuel Level channel by 2 to correct it?)

I tested it and it seems to work but I will compare against my IBUS readout some more and feedback.