Q: Can someone give some good info about turbo Eclipse Gen1 4G63T DOHC trigger pattern? Use optical sensor on cam with 2 signal wires and 2 for supply. It must be simple trigger.
- If 2 campulse, than MembersPage/Fero/MitsubishiEVO applies
- if 1 campulse, than choose "c004 with camsync" in VemsTune primary trigger dialog. That means 4 equally placed (180 crankdeg) primary trigger pulses.
This is NOT about "engine", but about a "trigger" setup (HALL/HALL where sectrig =camsync HIGH/LOW pulse length varies)
- this is supported
- Apparently all Mitsubishi EVO-s (that don't use some more standard trigger like 60-2) use this trigger setup (reported at MembersPage/Fero/MitsubishiEVO )
- There are no reported Mitsubishi triggers unsupported by VEMS
- If you report anything related, consider:
- InputTrigger/TriggerLog must be captured at least twice (with sectrig rising edge and falling ; at max 4 combinations if primary trigger falling/rising also tried, although primtrig is evenly spaced so not as important),
- scopeshot might be needed, and description with exact crankdegrees for each rising and falling edges (measured from cyl1 TDC)
This Mitsubishi has a HALL trigger on the camsync.
unfortunately
- precision is trash (due to cambelt sloppyness)
- period is same as if it was on crank (less information than normal cam signal: not enough for fully sequential, but enough for wasted spark)
The trigger is Coil type (one pulse per event ), but alternating positive and negative to distinguish 1-4 and 2-3 cylinders (are you sure?).
The trigger signal was recorded with a notebook, that's why the squarewave looks distorted (to sharktooth signal) by the highpass filter (series capacitor) on the notebook audio input.
With DVM DC=2.5V amplitude: AC ~2.5V is measured that you expect for a normal 0/5V signal with 50% duty. With engine off, 5V (DC) is measured.
The signal is currently processed with LM1815 and series condenser so it is theoretically universal considering trigger type (hall and VR). In 50% of cases, LCD displays right value, otherwise rough half of proper RPM.
if we reconstruct the original signal, we can see that
- pulse for cyl1,4 has a longer width
- pulse for cyl2,3 has a shorter width
Note that
- falling edges are equidistant
- good for triggering
- store timestamp in ptrig_capturedtime_prev
- rising edges are not equidistant (only useful for checking cyl1,4 vs cyl2,3 and updating igncount). pulsewidth=time since ptrig_capturedtime_prev (last falling edge)
- if this pulsewidth is (significantly, or with any amount) longer/shorter than previous pulsewidth than igncount=ignchmax
Find the correct cyl:
- camsync
- using bothedge ( LM1815 not suitable) and consider signal length: firmware modification
- modify primary_trigger_init() so IC1 initialized (similar to IC3 in secondary_trigger_init() ) that both edge triggers. Maybe setting just one edge and changing to falling/rising in interrupt is necessary
- detect edge in PRIM..TRIGGER interrupt
Any ideas, how to condition the signal?
- remove the 10k pullup on trig1 input inside v3.x (if not already removed)
Setup is not VR anymore, but the symptoms are the same
I converted the TRIG1 input to hall setup and removed 10k pullup as well, but I don't have stable RPM signal yet as I described above.
This must be something trivial. Eg. if you configure falling edge (primary_trigger bit0=0), RPM reading should be rock stable. Maybe you accidentally configured rising edge (primary_trigger bit0=1) ?
On the other hand I found an other trigger:
An other trigger found
I've found an other trigger probably from crank-shaft HALL because 3 wires are coming from the bottom of engine (I will check it soon). Wires: 0V, 12V, signal (0V or 5V).
Notes:
- I don't understand why 12V and why not 5V is on feed.
- Observation: AC and DC voltages are measurable between the trigger described here and above. (unfortunately this info is of little use).
- Signal levels are almost the same than in the previous case. DC=2-2.5V, AC=2-2.5V, same frequency (measured by DVM).
- Since I use this trigger I have stable RPM signal. It is good for setting up injectors, but not enough for ignition.
- coil type setup in config. TODO: the other relevant config, eg. rpmk[] and config13, etc..
- Does this facilitate to get the trigger needed for wasted spark?
- Is it worth to connect both triggers to primary and secondary inputs, and try to determine which cylinder to ignite with alien which is already implemented in the firmware?
We know too little about this. Scope snapshots would be nice. particularly, with 2 channel snapshot together with the CAM-HALL. Maybe connecting the
- crank-HALL to primary trigger and
- CAM-HALL to secondary trigger (configured for both edges or falling edge)
- simpler firmware modification and
- better ignition precision
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