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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6957
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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I have a 2003 Montero Sport Limited. I have a misfire in two

Customer Question

Hello Doug, I have a 2003 Montero Sport Limited. I have a misfire in two of the spark plug wire boots. We have changed the crankshaft sensor and the ignition module.
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.


Which cylinders are misfiring?

Customer: replied 1 year ago.
4-1 and 6-3. Also are we getting charged for every response or a flat fee for the conversation about the question?
Expert:  Doug replied 1 year ago.

Flat fee.

So you are getting actual misfire faults for cylinder 1,3,4 and 6?
If so, have you verified the coils are actually sparking at all on those two pairs?

Customer: replied 1 year ago.
Thats what I meant to say, I'm sorry, the coils are not sparking, as a result I changed the ignition module and the scanner also marked that the crankshaft sensor was bad so I changed that as well.
Expert:  Doug replied 1 year ago.


To have one coil operating and two coils not operating your only real suspects are going to be belt timing, ignition module (PTU), computer (PCM) and wiring in between. In addition to of course either the PCM or PTU burning out a driver (or two), if the belt timing is off more than a tooth the computer will automatically shut down two coils.
It is worth noting as well that if you have a flaky cam or crank sensor this could be misconstrued as a belt timing issue resulting in shut down.... you have to be extremely cautious with aftermarket cam/crank sensors because of this.

Do you have a multi meter we can use to test the PCM output?

Customer: replied 1 year ago.
I do have a multi meter. How do i go about testing the computer?
Expert:  Doug replied 1 year ago.

Take a look at the PTU... you will see two connectors on top, a three pin connector and a six pin connector. We are interested in test voltage on the six pin connector.
Take your meter set to DC Volts and ground one lead, then place the other on pin 1 (blue wire). Crank the engine and record the voltage behavior (peak voltage and if it is solid/fixed or fluctuating.
Move to pin 2 (Black/Yellow wire) and record the readings again, then move to pin 3 (White wire) and again record the readings, all while cranking.
Let me know what you find there.

Customer: replied 1 year ago.
Alright Im sorry. I'm closing the shop right now, is there a chance we could continue this conversation tomorrow?
Expert:  Doug replied 1 year ago.

Absolutely, just return here with your results tomorrow and post them up and I will get with you as soon as I see them. Just please allow me some time to respond if I am not at work yet or with another client when you post; I will respond to you as soon as I am available. Please do not relist or post a new question or I will not see your response (and you may incur additional fee that way). Just post back here is all you need to do.