This Suzuki 4cyl 1.6L (high-compression, NA firing order: 1342) engine had factory trigger originally
- no camshaft angle control on this engine (even camshaft sectrig sensor removed, which is not a problem as it has wasted spark COP-s, yes: the COP has a HV cable leading to the partner-sparkplug ).
- Subaru H4 sequence : (13, missing, 16, missing, missing) MM13M16 pattern in short, M as in Missing
- see other Suzuki, see MembersPage/SuzukiValveControl
- InputTrigger/SubaruThirtySixMinusTwoMinusTwoMinusTwo
I was called to review an engine that has "factory suzuki trigger", and is almost impossible to start.
- even basic things like InputTrigger/TriggerLog (and vemslog) hasn't been provided, which is a clear indication of serious installer carelessness (unforgivable when there are starting issues; Requests missing essential info is normally ignored, but this was 50mins drive, and kinda abandoned by the installer, thought to drive over to support).
I thought some configuration tweak would be needed. It turned out the installer instructed the mechanical crew to GRIND OFF teeth from the factory wheel and convert it to 12-2.
- the factory 36-2-2-2 is an awesome smart pattern
- it is supported by VEMS v3 firmware since 2011
- the 12-2 is one of the worst (12-1 is clearly the worst)
I started by capturing triggerlog. It became obvious from triggerlog that
- it's not the factory 36-2-2-2 trigger, but only 10 pulses
- it's likely 12-2
- but the missing tooth was placed at most unfortunate position, after TDC, and time-gap is only 200% not 300% when cranking with sparkplugs
- they swore that the correct teeth were kept (every 30 degs)
- (visual inspection) or cranking without sparkplugs could perhaps confirm this
When cranking with fuel and spark, the missing tooth disappeared completely. Something like 110..120 % but clearly not 150..200% or more (remember the N-2 missing tooth is theoretically 300% of prev tooth).
What could be done with such a crippled primtrig wheel ?
When no missing tooth is detected at the proper position (because of significant angular acceleration after TDC and combustion, during cranking) The firmware shuts down the inj/ign train (as it should). Perhaps not impossible to have some "10 tooth" special case to ignore such problem from crippled pattern at startup, but we don't like special cases too much (just for one broken install: but most likely there are half dozen from same installer, I suspect).
Griding further (after planning!) could be a solution also:
4-1 Path
...
6-2 Path
...
Factory 36-2-2-2 was put back in
- 36-2-2-2 (updated configlet will be needed)
TDC is 35 deg AFTER M in MM13M16 (we marked it using an empty block and shaft from the shelf)
Captured without sparkplugs, and trigger_tooth=0 and TDCdelay=70 :
If I set trigger_tooth=12 (0C) and TDCdelay=65 we get no spark attempts in triggerlog.
From Bench, the MM13M16 pattern:
This triggerlog is not yet captured from this engine, but was captured earlier during a benchtest of Suzuki_36_2_2_2_No_Camsync configlet (configlet has been updated with correct settings for 1.2.27 and up during testing)
For the curious, Suzuki 36_2_2_2 with stock camsync also tested an verified good (also from bench; this engine has camshaft sensor removed as said above ):
