[In Development] VT - VY Ecotec / L67 Spark Cut Rev Limiter

[The1]

Nice work!

I had some code to add to enhanced mod but never got time to finish it or test, I took out code for LPG they put in VY I think to help stop backfiring, they didn't set it to 0 but a very low value maybe 600usec.

[Chr0m3]

Nice work!

I had some code to add to enhanced mod but never got time to finish it or test, I took out code for LPG they put in VY I think to help stop backfiring, they didn't set it to 0 but a very low value maybe 600usec.

Cheers, if it's the code I'm thinking about that you mentioned, they do set it to 0 but there are overall min and max values that act as a boundary of sorts, that and the 3x ref is directly related to that limit as well, it's a bit odd I still have yet to work this out.

[JCSuperina]

Hey Chr0m3 when do you think we are gonna be able to access a prototype for the N/A VY bin?

[Chr0m3]

Hey Chr0m3 when do you think we are gonna be able to access a prototype for the N/A VY bin?

Hey, no ETA yet, still a lot I need to look at and test that and time, I don't have a lot of it currently.

[vlad01]

That's interesting. I'm not familiar with the newer Delcos, but I know a bit about the 424 in the VR and now that had some limitations in these regards where as the older 808 family had much higher rpm and map limits compared to the later 424. 9600 vs I think 8k?

The one thing that always perplexed me is 11p/424 has a 255km road speed fuel cut limit that can't be increased or disabled. No such thing exists on the 808/12p.

[Chr0m3]

That's interesting. I'm not familiar with the newer Delcos, but I know a bit about the 424 in the VR and now that had some limitations in these regards where as the older 808 family had much higher rpm and map limits compared to the later 424. 9600 vs I think 8k?

The one thing that always perplexed me is 11p/424 has a 255km road speed fuel cut limit that can't be increased or disabled. No such thing exists on the 808/12p.

Interesting, I know these ECUs can only rev to about 6400-6500 before the burn time gets too excessive (calculation overflows) and causes "misfires" I've actually created a thread and written about how I overcome that limit here. In regards to the speed cut, could it not be patched out entirely? (I'm not familiar with those ECUs), I patched out speed cut for free room to add code related to spark cut in these ECUs.

[vlad01]

Hmm that seems a pretty low rpm to have issues with rpm. I know Gareth when I was helping with his speedway tuning years ago had no issues with rpm close to 8k on the 424, that was approaching the limits of the tables iirc, but the engine made peak around the 5k mark I recall so the revs that high weren't really needed.

The Formula guys run a stock 808 code where the tables run out at 4800, but the ECU has no issues projecting tables beyond that running those cars at 6800-7200k all day long.
12p extends the tables to 9.6k but I don't know if anyone has run any engines that high on the 808 but I don't see why it can't since it's much lighter on code than the 424 with it's 11p and it clearly had no issues close to 8k.

I would have thought the newer ECUs would handle this even better since they have a much more capable CPU, or is the code on them that much more bloated?

I assume the speed cut could be removed, but VL400 has disappeared long long ago and has the 11p and 12p code from my understanding, so further development on 11p and 12p halted, but as I know, 12p is tapped out as there is no more ram or resources available to do much else without removing vital features, 11p is a different story, being auto code that was built with more resources in hardware that can be forced to run as manual, heaps could be freed up getting rid of the auto stuff. 424 had big potential as it's map and has many of the desirable flexibility and features and ease of tuning as the 808 but has more resources and better I/O and spark control and high speed data, if the auto stuff is removed and repurposed there would be heaps more that could be done with the ECU.

The 424 is also easier and cheaper to get being out of plain Jane VRs which are more plentiful and newer than the VN or VP.

[Chr0m3]

I honestly couldn't say why it happens, it's very weird and almost like a hardware limitation..

Video I did explaining what I understand and showing what happens etc..

[Nick97]

Highest I can get fuel cut is 6375rpm. So have you modified that to be able to be set higher?

If you set the limiter to 6375 on factory code it will skip the limiter all together, this is because the code checks if the rpm > what you set, and 6375 is 0xFF in the calibration so it's max and can't get any bigger, so if it's not above the limit it will skip the limiter, you can patch the ECU to read the RPM from a 16 bit address instead and read up to 8000+ RPM however at 6500+ RPM the spark control becomes less then average.

The way this works is factory code has RPM as an 8 bit value that uses 25 RPM per bit, so the max a 8 bit value can be is 255 which is 0xFF in hex and 255 x 25 = 6375.

So yes it can be done but in my opinion there's no point until you sort out the spark control issue, that and the ecu would require more patches to extend the tables to be able to "tune" at that RPM.

thats awesome work!!

i feel like i know you from GTA days but cant quite remember if it was ChromeXmods or something like that

[Chr0m3]

Highest I can get fuel cut is 6375rpm. So have you modified that to be able to be set higher?

If you set the limiter to 6375 on factory code it will skip the limiter all together, this is because the code checks if the rpm > what you set, and 6375 is 0xFF in the calibration so it's max and can't get any bigger, so if it's not above the limit it will skip the limiter, you can patch the ECU to read the RPM from a 16 bit address instead and read up to 8000+ RPM however at 6500+ RPM the spark control becomes less then average.

The way this works is factory code has RPM as an 8 bit value that uses 25 RPM per bit, so the max a 8 bit value can be is 255 which is 0xFF in hex and 255 x 25 = 6375.

So yes it can be done but in my opinion there's no point until you sort out the spark control issue, that and the ecu would require more patches to extend the tables to be able to "tune" at that RPM.

thats awesome work!!

i feel like i know you from GTA days but cant quite remember if it was ChromeXmods or something like that

Ahahaha yeah Chr0m3 x MoDz was me in the GTA days!