Installing a VEMS unit on a stock 89 Porsche 911 Carrera 3,2.
MembersPage/MacB/Config <- please verify
http://www.vems.hu/files/MembersPage/MacB
Good spark events with this c129 trigger (because of divby43, only 3 primtrig shown in triggerlog between sectrig pulses, not 129):
How it was made
- The "nr of cylinders" is only used by the ECU for the RPM calculation.
- For 6 cyl, normally 6 cyl must be configured (when 1 sectrig pulse every cam rotation). Possible with same primtrig setup, using "c258" trigger: that means using third (cam-HALL ) sensor masking out every 2nd pulse
- Since for the c129 trigger there is 1 sectrig pulse every crank rotation, in this case, "3 cyl" must be configured. (of course 6 injector outputs can be used).
- minimum 3 ignouts must be configured, even if all are the same (eg. when using distributer)
To adjust and verify "TDC after the trigger" setting, of course it's always good to verify actual spark-timing with strobelight, using 2 different sparkangle (eg. 2 deg and 18 deg).
Open Issues
Help needed
- Can��t get the sectrig working:
- Can only get the primary trigger (129 teeth) to record anything in trigger recorder.
- When I enable the CamSync for Sectrig, I don´t get any recordings anymore.
- Tried out several pinnings of the two VRs, but nothing helped. See triggerlogs. under /Config
- Also tried to disconnect ground to Pin13 but without success.
- Actual settings:
- speed sensor (129 teeth) to Pin 27
- refernce sensor (1 tooth) to Pin 12
- Pin 13 grounded (same ground like Pin26)
- Actual firmware: 1.2.11 (Any other firmware needed ???)
- http://vems.hu/vemstune/bugreports/reports.php?cmd=view&key=tqeigX
- Alternative trigger setting can somebody <- please verify
- Number of cylinders = 6
- Audi trigger divider = 43
- TDC after the trigger = 60.0
- Number of Teeth On Wheel = 6
- # of teeth of full engine cycle = 6
- First trigger tooth = 0
- Next trigger tooth = 1
- Angular Width of Tooth = 120 degrees
- Reference trigger tooth table = 0, 5, 4, 3, 2, 1
- This looks much nicer in VEMSTune Trigger Settings Visual, but will it work ???
- masking the sectrig to only consider every second pulse ?
- injectors are grouped 1,2,3 and 4,5,6
- Req Fuel (Injector size) = 14.9ms (6,49 *(3164ccm/6/229,1ccm/min))
- Injector firing Divider = 3
- Number of primary injectors = 2
- Coil charge time @13,2V = 3,01ms
- is this a good start value for a single BOSCH coil setup ?
Engine specs
- 3,2litre flat-six normally aspirated
- number of cylinders=6 (even fire)
- trigger system is 2 VR sensors on flywheel / starter ring gear (crankwheel)
- rev sensor is sensing 129teeth per crank rev
- 43*3, so divide-by-N N=43
- the rest like reference tooth almost like with 3 teeth on the crank: a c003 trigger if sectrig comes just from 1 crankpulse, ( or c006 if camsync is also installed - which is not, at least initially )
- TDC sensor is sensing 1 pin on flywheel (don´t know yet how many degrees before TDC).
- Will likely need to have (access to) a strobelight to verify all is well.
- rev sensor is sensing 129teeth per crank rev
- no cam or distributor sensor
- with auditrigger camHALLinverter the EC36/13 input must be grounded to allow the crankhome-VR pulse to go through.
- stock NTCII at cylinder head #3
- AFM (flap type) will be removed, will use TPS instead (exchanging stock idle and WOT switch)
- idle control valve is the "silver cigar" BOSCH thing, two wires to ECU, so PWM
- IGN distribution will remain untouched in first step, stock coil, stock distributor
- stock fuel injector BOSCH 0-280-150-158 low-Z (2-3 Ohms)
- order with "low-Z extension" option if you keep the high-Z injectors (and configure PWM-ing: ~35% PWM duty after 1msec full-voltage)
- wideband O2-sensor will be used intead of stock narrowband
- no MAP.
- It would be easier to tune with a MAP sensor, but also possible with TPS, with more work
- MAT now planed
- The MAT sensor is almost a MUST (in a normally aspirated engine MAT sensor can be an NTC in the air-filter, very simple and cheap, just make sure the engine will never inhale it)
- Firing order is 1-6-2-4-3-5 for the Carrera
- wiring should remain mainly stock with stock-DME-connector and only additional wires for wideband, TPS and so on
- planning to use alpha-N only
Trigger: div-by-43
- primary trigger: 129 is 43*3
- that is 43 per event: 43 is a prime number so cannot be divided. Therefore divide by 43 is the way to go with this trigger: the only way
- 129 means 258 for a full engine cycle, the max value for "Coil-type" + "normal" is 255 !
- using a divider is a must anyway, because only that allows a race-condition between secondary trigger and primary trigger, should the 2 falling edges of primtrig-VR and sectrig-VR be close
- timing from 3 pulses means that (crankhome-VR) pulse must be 35-75 crankdeg BTDC.
- Also, during cranking, relative angular acceleration is high (does not double, but RPM * 1.3 is possible) between consecutive events, so, as a result the actual spark will be slightly delayed during cranking when the engine suddenly comes alive
- this can be somewhat compensated with a few degrees higher sparkadv at 400 RPM. Does not effect normal running (even quick acceleration in gear1).
- if really 129, than 43 tooth per event per (if 6cyl). But with divby3 (and 43 tooth total,) next_trigger_tooth=14, 14*3=42 tooth (~2.75 degree percylinder spark delay) can be used to compensate this tooth...
- important: divby4 (11*4=44) is clearly invalid, there is no integer T=tooth_count for which 4 * T = 129 so trigger error would always be on with that (if it would run at all)
- So I need to use "Auditrigger DivbyN" option and a "Audi trigger divider" of 43.
- So number of teeth on wheel becomes 3 (carrying over what I see on the AUDI configs) confirmed!
- First trigger tooth = 0
- Next trigger tooth = 1
- Angular width of teeth = 120°
VEMS-spec: / Needed parts
- VEMS Board version v3.6
- Serial nr.= 8234
- (Order ID= 8044)
- Flyback: LowZ active flyback 8ch
- ignition driver: 8
- primary_trigger: EC36/27 VR
- secondary_trigger: auditrigger w/camHALLinverter
- Knock input channels: 0
- LCD connection: no
- MAP connection: offboard(electronic)
- mounting-style: no-screws
- 1-wire interface: no
- EGT input: no
- PS2 connection: no
- withSDcard: no
- Other stuff:
- TPS from E36 (Hella): 6PX 008 476-111
- Adapter plate DIY
- WBO2 (Bosch): 0 258 007 351
- MAT (Bosch): 0 280 130 039
- intake pipe DIY
- 1 x Wideband connector
- 1 x Econoseal18-Wire side
- 1 x EconoSeal36-Wire side
- Some other connectors etc.
- TPS from E36 (Hella): 6PX 008 476-111
Related projects by other users:
Looks like a similar setup: MembersPage/KevinBlack/PorscheTurbo