506 revlimit hysteresis and ignition cut instead of fuel cut

[Adhamkhe]

Hi.
Theres a problem that im struggling with and would be very thankful if someone have a solution
Running 506_soft965 on 413 red label
Revlimit seems to be soft limit (fuel cut ) set 7000 rpm
Fuel and ignition tables limit 6500 rpm
Ignition dwell limit 7000 rpm

The question is. Im not finding a way to get an ignition cut at 7000 rpm.
Could i get it at 6500 by retarding the ignition table and setting ignition dwell time to 0 ?
And is there another way to get the flames and pops at the revlimit (no fuel cut )?

Im sorry if im missing something basic or obvious
Thanks in advance

[olafu]

You must to find way to disable ignition secondary current monitoring when using ignition cut in rev limiter. Otherwise you will get coil fault codes on random cylinder(s) and DME will switch their injections off. In dirty way you can ground DME pin 15, and you get fault code from secondary current monitoring, and this fault mode fuel cut doesn't work anymore, then it's possible to play with dwell based revlimiter.

I tried to find similar "control bit" for ignition cut, what is used in standard fuel cut revlimiter, but without success. I don't remember if there is some bit what is checked before primary current switching, but anyway it's not trivial. M3.3.1 revlimiter is part of main loop, it checks every times engine speed. If speed is over limit, it will cut injection, if not, it will do nothing. Quite slow loop running speed causes behaviour like it has some hysteresis.

[Adhamkhe]

Thanks for your reply olafu
Ill keep trying and will let you know if i have any success with that
Also im searching for the hysteresis but no success yet

[olafu]

There is no actual hysteresis in revlimiter. Only behaviour like it has.
This is 413/623's revlimiter code, 506/965 has similar revlimiter, but it reads revlimit value from RAM (0x18A8), instead of reading it from ROM in 413/623. 506/965 program has also part which is used to read revlimiter values from vehicle speed based table and stores it in to RAM: 0x18A8.
Revlimiter is also in slightly different place in 506/965. It starts from 0xADE9 instead of 0xADD5 in 413/623 bin.

Code: Select all

ROM:0xADD5	cmp	INTMEM_40, 30h[INTMEM_68]	; compare INTMEM_40 to revlimit value
ROM:0xADDA	jnh	ROM_ADDF			; jump to 0xADDF if RPM is lower than revlimit value (jump over the fuel cut activation)
ROM:0xADDC	orb	INTMEM_C7, #01000000b		; bitmask - C7 bit6 = 1 (=fuel cut active) 
ROM:0xADDF	.... (program continues)

[biela]

Hello

In wich ROM line is applied the fuel cut?

Or, where in the code is read(compared) bitmask - C7 bit6 = 1?

Thanks

[olafu]

It's same flag what is used everywhere if fuel is needed to cut off, as example overrun condition. I can't surely say where this flag is turned back to "0". If i remember, the rev limiter is part of the main loop, so it's read about 100 times in a second on idle and about 10 times in a second on max rpm.

Dwell value is also stored somewhere, so it can be cleared instead of bitmask action if rev limiter comes active. But if dwell is refreshed after revlimit function, it doesn't work. There is also flag what cuts ignition AND fuel, but i can't remember what it is and what other things it does. I was never found flag what controls only ignition. Dwell time is possible, it's stored in somewhere, so if dwell is cleared, there is no charging time on coils. Same fuction as modify dwell table: Last rpm axis data is bigger by one, but dwell is 0. But it causes misfire fault codes, so it's necessary to modify misfire triggering conditions or turn misfire control off before revlimit is achieved.

[mahdi93]

tried this for pop and bang but engine backfire from intake manifold
what is wrong or how can i make it ?

[Adhamkhe]

tried this for pop and bang but engine backfire from intake manifold
what is wrong or how can i make it ?

Lower fuel on deceleration zone and increase ignition retard to -22 at least part throttle. The max retard on 413 and 506 is -45 do that for idle when vanos retarded
It shouldn't pop from the manifold