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Summary of change:
I´m planning on installing a VEMS unit on a stock 89 Porsche 911 Carrera 3,2. '''Plans''' * Motor 3,2litre '''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. - 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) - 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 - no airtemp sensor planned. 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 ! (and using 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) * 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 will be 0 Next trigger tooth 1 Angular width of teeth is 120° reference tooth is 0-5-4-3-2-1 '''"Auditrigger" option for the ECU.''' * any drawbacks due to the 129 teeth variant, like rev limit or so ? ** 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) * secondary trigger is the TDC-mark on flywheel * what to do for the low-Z-injectors ? is the 30V flyback ok and do i need the inline resistors (6,8 Ohm) ? ** '''order with "low-Z extension" option''' if you keep the high-Z injectors (and configure PWM-ing: ~35% PWM duty after 1msec full-voltage) '''Here is what I ordered:''' 1 x Wideband connector 1 x Econoseal18-Wire side 1 x EconoSeal36-Wire side 1 x ECU VEMS V3 - 1-wire interface: no - EGT input: no - Flyback: LowZ active flyback 8ch - ignition driver: 8 - Knock input channels: 0 - LCD connection: no - MAP connection: offboard(electronic) - mounting-style: no-screws - primary_trigger: EC36/27 VR - PS2 connection: no - secondary_trigger: auditrigger w/camHALLinverter - Service: normal - withSDcard: no Other stuff: TPS from E36 (Hella): 6PX 008 476-111 WBO2 (Bosch): 0 258 007 351 Some connectors etc.
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