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heliolps2 heliolps2 is offline
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Join Date: Jan 2009
Location: DC
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DISTRIBUTOR TRIGGER SIGNAL

The second most common cause of 930 engine ignition failure is the ignition trigger circuit. Since the ignition box is controlled by the magnetic pulse generator located inside the distributor, any disruption in the triggering signal will cause ignition problems. Full disassembly and inspection of the distributor is highly recommended due to the intermittent nature of triggering problems. Pay special attention to the distributor trigger shielded cable ( green wire ), magnetic pulse generator magnet and magnetic pulse generator winding connection as these parts are known to fail in combination. An especially common problem is a broken magnet pole.

Evidence of arching between the magnetic pulse generator magnet points indicates a defective rotor. In this case replace the rotor, magnetic pulse winding, green wire and ignition box. The Perma-Tune high performance triggering is so accurate that worn out distributor shaft bearings can be detected by the tachometer. This is indicated by the tachometer needle slightly bouncing at idle and is usually accompanied by excessive end play of the distributor shaft. Trigger signal problems can cause double triggering which results in a weak ignition spark. Due to the lower triggering resolution of the stock ignition box, some symptoms of trigger signal problems can be more evident after the Perma-Tune is installed. Refer to the vehicle maintenance manual for triggering signal waveform specifications and distributor repair instructions.

To quickly test the triggering circuit without the use of an oscilloscope: Unplug the harness connector from the ignition box. Refer to the 930 6 pin Installation Instructions diagram; connect an Ohmmeter between pins 3 and 6 of the harness connector. To prevent the possibility of misdiagnosis, tug on the green triggering signal wire located at the base of the distributor while viewing the meter. The published specification for the magnetic pulse generator is 600 Ohms +- 100. Our experience has shown that a variation of +- 25 Ohm indicates a need to repair defective connections or to replace the magnetic pulse generator windings.

In my case the green wire behind the connector is coming loose, Pin 6

BENCH CHECK OF THE IGNITION BOX.

1 = System ground
4 = Coil + Hot (coil - to ground)
2 = Tachometer signal
5 = Power
3 = Signal ground (distributor pin B) Green wire shield
6 = Signal (distributor pin A) Green wire center conductor
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1986 944 turbo -first car
1997 993 Cab 6 speed-sold
1992 964 C2 turbo
SOLD, 911GT ,CIS, 428 fwhp 450 trq, Carrillo rods, 964 cams, TT retainers,7.5 comp 1.1 bar boost 320 ml black fuel head 009 injectors, 044 pumps, 60-1 T4/T3 dual scroll turbo
Old 06-03-2011, 07:50 AM
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