Extending the high rpm dwell limits of the VX / VY flash PCM

[The1]

good work Ive sent you some more information to see if it helps and go from there.

[The1]

I played with scope last night.

(Each count around 15us) (Stock values mindwell A4=164*15=2.46ms minburn 24=36*15=0.5ms)

From looking at your table id say around 3ms total is the issue with code loop at higher rpm and hitting minimums. With fuel cut disabled ecu seems to rev and keep injectors going to the 8k limit ok.

Doing some research looks like the dwell time even in factory code is way to high at lower rpm, no wonder coils eventually die from heat.

Dwell time 1.5ms - 2.0ms ideal enough to saturate the coils.
Typical in-cylinder burn durations: 1.0 - 1.5 ms including boosted engines. Seems down to 0.8ms for N/A can be ok.

Calculating the timeframe windows down to 8000rpm gives us 7.5ms so there's plenty of time.

Need to look at dwell code and make a new routine to fix it i guess.

[Chr0m3]

I played with scope last night.

(Each count around 15us) (Stock values mindwell A4=164*15=2.46ms minburn 24=36*15=0.5ms)

From looking at your table id say around 3ms total is the issue with code loop at higher rpm and hitting minimums. With fuel cut disabled ecu seems to rev and keep injectors going to the 8k limit ok.

Doing some research looks like the dwell time even in factory code is way to high at lower rpm, no wonder coils eventually die from heat.

Dwell time 1.5ms - 2.0ms ideal enough to saturate the coils.
Typical in-cylinder burn durations: 1.0 - 1.5 ms including boosted engines. Seems down to 0.8ms for N/A can be ok.

Calculating the timeframe windows down to 8000rpm gives us 7.5ms so there's plenty of time.

Need to look at dwell code and make a new routine to fix it i guess.

I've done the math etc and figured out pretty much what you've said, however my limitations are I've not scoped a running car to know what's acceptable dwell wise to know what I have to work with, happy to work together on enhanced if you are interested in trying to work something out, it's an issue that does need to be addressed for real builds haha.

The dwell isn't really the issue, it's the burn time which is directly related I know, but yeah the burn time is what kills the RPM I believe.

Edit: After re-reading your post it looks like you're saying the dwell my patch has should be fine, I'm just not sure about the burn still, might be a bit high and a bit low in some areas.

[The1]

yeh if we look at the dwell code hopefully should be able to mod it to get a balance.

[immortality]

Would it be possible to add dwell control settings in the tunes so people can run different coils?

[Chr0m3]

Would it be possible to add dwell control settings in the tunes so people can run different coils?

Of course it's possible but a lot of work haha.
Well not really a lot but yeah, will take a bit to get it right I'd say.

[The1]

With Chr0m3's help looking at the dwell code and tearing hair out with arduino we made some progress i think.

Will have to see if the tweaks work in the real world, then mod the Fuel cut limit table.

Code: Select all

RPM	Dwell (ms)	Burn (ms)	Max Window (ms)
1000	7.5		12.0		60.00
1500	6.2		7.1		40.00
2000	3.7		6.3		30.00
2500	3.2		4.4		24.00
3000	2.9		3.7		20.00
3500	2.8		2.8		17.14
4000	2.8		2.2		15.00
4500	2.7		1.6		13.33
5000	2.4		1.5		12.00
5500	2.1		1.5		10.91
6000	2.0		1.5		10.00
6500	2.0		1.5		9.23
7000	2.0		1.5		8.57
7500	2.0		1.5		8.00
8000	2.0		1.5		7.50

[Chr0m3]

With Chr0m3's help looking at the dwell code and tearing hair out with arduino we made some progress i think.

Will have to see if the tweaks work in the real world, then mod the Fuel cut limit table.

Code: Select all

RPM	Dwell (ms)	Burn (ms)	Max Window (ms)
1000	7.5		12.0		60.00
1500	6.2		7.1		40.00
2000	3.7		6.3		30.00
2500	3.2		4.4		24.00
3000	2.9		3.7		20.00
3500	2.8		2.8		17.14
4000	2.8		2.2		15.00
4500	2.7		1.6		13.33
5000	2.4		1.5		12.00
5500	2.1		1.5		10.91
6000	2.0		1.5		10.00
6500	2.0		1.5		9.23
7000	2.0		1.5		8.57
7500	2.0		1.5		8.00
8000	2.0		1.5		7.50

Looking much better then the first result you showed me

[Chr0m3]

I've had some time and a good setup to test with, need to verify on dyno but on a street test at 6500 (with no limiter) it was like it hit a wall, wouldn't go anymore was acting sort of like a limiter, I patched the code and got to just under 7000 RPM before I had another issue, stay tuned..

[The1]

awesome, it's a hard one cause there's no other way then really testing it for real lol.