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

[Chr0m3]

Hi everyone,

Although this is my 1st post here, I've been lingering for a while and I've done quite a bit with these ECU's with some of my projects, some of you may have even seen my content or YouTube, Facebook or TikTok (Chr0m3 Motorsport), I've been researching and developing spark cut on the VX / VY flash ecu for about 3-4 years now with decent success, and what I've learned in doing that has made it fairly easy to convert it to other ecus.

My background is from Xbox 360 modding for the most part, some of you may even recognize my name from that scene if you ever modded anything *cough* GTA *cough* on 360. I've started this topic as I'm wanting to develop the spark cut limiter on VT - VY N/A & L67 factory ecus and then eventually do a public free release of it for everyone. I have successfully developed a form of spark cut limiter for VT N/A and VY N/A so far, this thread is about showing the progress and testing etc, once it has been developed and tested for all it will be released, I don't have an ETA yet, judging by the fact it seems to work on VY and VT, I have no reason to believe it won't work on VX and L67.

Here's a video of it on N/A VT, all factory ecu no added hardware or anything like that, we did have an 18x code at the end of the night, have masked out some other codes in testing, 18x could be a bad crank sensor but it needs further investigation, car did go 2 rounds of 2 min + abuse and didn't seem to have any negative effects but is still under testing etc for this.

VT spark cut test video:


https://www.facebook.com/share/r/NqA12QAR4d5umeWf/

VT N/A:
Progress: In testing

VX N/A:
Progress: Not started yet

VY N/A:
Progress: In testing

VT L67:
Progress: Not started

VX L67:
Progress: Not started yet

VY L67:
Progress: Not started

As with any code patches to the factory ecu, there are risks and this is what really needs to be investigated, I'm not aware of any issues so far but it is all still being tested, I will keep everyone updated, might open up to testers at a later date but for now it's private testing only.

[immortality]

Looking forward to your progress.

[pman92]

Awesome to see a bit of active development on the old Delco hardware.

Does it work by setting dwell to 0 similar to the spark cut in $11P?

Another topic you might be interested in:
viewtopic.php?p=117468

[Chr0m3]

Awesome to see a bit of active development on the old Delco hardware.

Does it work by setting dwell to 0 similar to the spark cut in $11P?

Another topic you might be interested in:
viewtopic.php?p=117468

Basically, but as discussed you can't pull the dwell down to 0, can get it low enough to misfire but yeah, still definitely needs more research and testing.

[turbo_v6]

I'd look for a min dwell parameter. When I did it with the P59 that initially caused issues.

[Chr0m3]

I'd look for a min dwell parameter. When I did it with the P59 that initially caused issues.

Cheers, yeah I think I have found min dwell and from what I can tell it doesn't make any difference.

I do have another idea I'm looking at, be really handy if I could test this on bench with an oscilloscope haha, I've only tested in car so far and that slows me down.

[Wade]

Would be nice if we could have idle spark changed in the flash based pcm’s. At the moment idle spark is referenced via coolant temp. But if it were referenced via mgc would make idle spark easier with larger cams ect. Same with dfco adding spark control of that would be nice, especially with a manual transmission seems to be the 2 biggest requests I get. Can you do a ghost cam idle and crackle an pop tune

[Chr0m3]

Still researching all of this, I'm now running an ecu on bench and able to actually monitor the EST output on a scope, this has helped a lot with testing and it's also shown some issues that weren't noticed in car.

Will keep everyone updated as I continue with this.

Unrelated to this topic, however I've also started researching extending the dwell capabilities of the flash ecu to handle more rpm, I've discovered at 6500-6600 rpm the spark delivery is less then ideal with factory code..

[Wade]

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

[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.