Odd fire 90,150,90,150,90,150 degree V6
Now even the factory 30,90,30,90, ... factory maserati trigger is supported even with the dual camsync pulse (1.1.90 firmware). See below.
Non-maserati triggers
Common denominator is 30 deg, which suggests 12 teeth on crank (also called 24+1 pattern with Tools/Play-trigger type c024)
Bench tested configs using per cylinder spark delay:
Maserati factory trigger setup primtrig pattern 30,90,30,90,30,90, 30,90,30,90,30,90 with double camsync pulse
[Maserati biturbo .wav] made by Phil.
- Bench tested OK with 1 campulse even with 1.1.88, using this [config ]
- same config with 1.1.90 now works with dual camsync pulse
- easy way to configure: at the bottom of "primary trigger" dialog: used configlet: Maserati Z012 (after VemsTune ini update or VemsTune newer than 2011-04-19 )
- note: a similar trigger (but 10 cyl instead of 6 and 1pulse camsync) is the Viper engine: MembersPage/PeepPaadam/BMWwithViperEngine VemsTune Tools / Play trigger: "Z020"
- obviously ignition outputs must be configured (according to wiring), and TDC-delay adjusted with strobe.
- It's a good idea to strobe just one ignition output first and note which cyl each slot belongs to (the rest ignouts disabled, or disconnected, also with injectors and/or fuelpump off)
- only install the WBO2 sensor in the exhaust after the engine started (for longer WBO2 sensor life)
For the curious:
- similar to Fiat Stilo, triggering from short-gap (neglecting the 90 deg gap and timing from every 30deg pulse, but using per cylinder spark delay)
- but advanced filtering enabled and 125% threshold (eg. Normal tooth 20-125%, missing tooth 125%-425%)
- to get odd fire output with this setup (and proper timing), per cylinder spark delay is needed
- Could you elaborate this spark delay?, 2 delays should be needed ?
- What about sequential injection ?
- needs strobing to find ign_tdcdelay (TDC after the trigger) value.
- Any idea (speculation or measurement) about the pulse position wrt TDC ?
- from the workshop manual it is 10° before TDC, also the Microplex firmware substracts 10° from the ignition map value after reading it.
- Any idea (speculation or measurement) about the pulse position wrt TDC ?
Reftooth-based solution might be another option WARNING: not yet passed testing with missing tooth + uneven odd-fire reftooth table !
- 12-1 teeth on crank is another rational pattern (3,5,3,5,3,5 differences in reftooth because tooth width=30 degrees).
- or 36-1 (9,15,9,15,9,15 differences in reftooth because tooth width=10 degrees)
- or 60-2 (15,25,15,25,15,25 differences in reftooth because tooth width=6 deg) also makes sense.
As you see, that method is about
- the reftooth table.
- but firmware mod required (in avoid_tooth() function) for uneven reftooth table otherwise it would attempt timing from nonexistant tooth
- obviously the secondary trigger must be enabled as camsync
- also, enabling the odd-fire bit might be needed so the RPM does not fluctuate up/down according to 90/150 degree time, but measures every second event (240 degrees)
- maybe some cheating with the cyl number also needed to show correct RPM (the cyl number has no other effect currently)
Page needs to be cleaned up
- also we'll make index page to different odd fire engines (and some generic instructions).
- Generic information will come to this page, and specific to the Maserati biturbo goes to MembersPage/FPhil (started with very similar content)
The solution to set 30 crankdegree teeth on the crank pulley was also recommended by Matthias on [Vems uk]
"The sensors are VR but it is not a big problem to make a Hall signal from them" [VR=>HALL] converter available (with divider option for multitooth ABS sensors).
I can filter out one of the crank trigger or even I can divide the triggers by two to make 2 x (1cam trig +3 crank trig) each for one even fire 3 cylinders, for respectively the left bank and the right bank of the engine . But in this last case I need 2 GenBoards !!!
This is what Maserati has done for the late biturbos: 2 triggers + one ecu (ignition+injection) for each bank
The 30,90,30,90,30,90, 30,90,30,90,30,90 arranged according to ign events, 10 crankdeg BTDC tooth marked bold:
- 30, 90, 30
- 90
- 30, 90, (next crankrot: ) 30
- 90
- 30, 90, 30,
- 90
10 crankdeg BTDC cannot be used as trigger tooth normally, eg when sparkadv is 20 crankdeg.
- so normally trigger tooth will be 10+30=40 (or possibly 10+90=100 BTDC ?).
- 10 BTDC could (ideally should !) be used during cranking though.
BTDC angle in (parentheses) :
- 30, 90 (40), 30 (10 / 100)
- 90 (10)
- 30, 90 (40), (next crankrot: ) 30 (10 / 100)
- 90 (10)
- 30, 90 (40), 30 (10 / 100),
- 90 (10)
TODO: insert campulses please
So for normal (non-cranking) sparkadv (say 18 deg, but for any >10 we seem to need
- 40,100, 40,100, 40,100 BTDC triggertooth (that is actually the last tooth before a normal sparkadv)
- so neither clean way will work: short-gap or long-gap setting: we need alternating after-short-gap and after-long-gap
The good news is that if firmware userspace "triggertooth" calculation can be taught about the uneven tooth-times (modifying the userspace easier than the interrupt timing code state machine), that might provide an 1.1.x solution without the per-cylinder spark delay tweak.
- config:
- coil-type
- odd-fire bit enabled
- toothwidth=30 deg
- AND nr of tooth=6 (not 12 !)... this special value together with toothwidth=30 could mark this Maserati trigger for now.