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Doug C.
Doug C., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8652
Experience:  Mitsubishi trained and employeed technician
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i have just bought a 3.0 24v shogun. it is only firing on four

Customer Question

i have just bought a 3.0 24v shogun. it is only firing on four cylinders.the coill pack on the left hand side is not working. i have fitted a brand new coil pack with no effect.what is the most likely cause to investigate next. and can the transistor pack be checked easily
Submitted: 4 years ago.
Category: Mitsubishi
Expert:  Shantal-Mod replied 4 years ago.


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Customer: replied 4 years ago.

yes please continue

Expert:  Shantal-Mod replied 4 years ago.


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Expert:  Doug C. replied 4 years ago.

Sorry for the delay.

The ignition system has a few components in line to develop spark:

Crank sensor gives inital timing to PCM
PCM splits this into 3 signals via 3 internal drivers
PTU (transistor pack) receives these 3 signals and converts them to 3 ground pulses
Each coil receives a ground pulse to fire

If you have swapped the coil and the problem remains on the same cylinder pair this, apart from wiring, leaves you with only a PCM issue or PTU issue. Both are common, and neither any more particular than the other.

The PTU has two connectors, a six pin and a 3 pin connector. The 3 pin connectors are the ground outputs to the coils; there is no real need to test here since we know there is no signal going to the coil and the wiring is short enough you would see if it was damaged.
The six pin connector going into the PTU houses the 3 wires for triggering the transistor for each coil pack.

Pins 1 2 3 on the six pin connector are your trigger wires (looking at the wire side of the connector, button on top). While cranking (or running if it will) you should see a low voltage pulse on each of these wires.... 300mV to 3V peak. If you see zero voltage, or a high fixed voltage (over 4V), the PCM or wiring to the PCM is bad.
If you see normal range pulse (300mv to 3V maximum pulse) or extremely close (250mV is OK, 3.2V is OK) on all three wires, the PTU is bad and will require replacement.