I'll check it, for sure, but I'm wondering... if the arcing stopped when I pulled the other plug wire off, wouldn't that suggest a wire problem instead of a coil problem?

Anyway, I'm trying to test the ignition module, or what the manual calls the "ignition power transistor". I just bought a new digital meter, but the manual very specifically says " an analog type circuit tester should be used".

I'm pretty good at mechanical, but anything electrical is not something I'm good at, so enlighten me. Is there a specific reason I shouldn't use my digital? Am I going to fry a potentially good module somehow?

I believe the "ignition power transistor" is the component the ECU switches to turn coil primary on/off. It should be about 1 inch x 1 inch flat black near the coil(s). A transistor is just a switch.

I don't know the specific instructions you're reading but an analog meter sweep needle will show the voltage switch must faster than a digital meter.

Your trying to see the primary coil voltage go from the spec'd amount (12 maybe) to zero and back, over and over as the engine cranks.

And/or trying to see the signal voltage from the ECU (5 volts) go on/off.

Depends which connection you're testing.

New job, and the Montero got put on the back burner.

I was able to test the ignition power transister, and it tested good. Don't know if I mentioned it previously, but I tested one injector connection with a noid light and it flashed, indicating that it was getting a signal when cranked. I only checked one, because everything is so difficult to get to.

So the fuel pump is pumping (though I don't know the actual pressure), the injectors seem to be getting a signal, and the ignition power transister tests good. I have no spark at any of the 6 plugs.

The manual lists the order in which things should be checked for a "no start" condition. They are...

1. Power supply (MFI relay) and ignition switch.

I haven't checked it because it's buried in the dash with no way I can see to get to it without removing the dashboard. Absolutely stupid design. From what I've read in the manual though, if this relay was bad then the fuel pump wouldn't work.

2. ECM power ground.

Haven't checked, but will.

3. Fuel pump.

I hear it working.

4. Ignition switch-ST and park / neutral position switch

Haven't checked, but based on the previous owners report that "it just stopped", I'm guessing this might not be the cause.

5. Camshaft position sensor

6. Crankshaft position sensor

I'm leaning toward one of those two now. The problem is, the manual lists a test procedure that involves a scanner or oscilloscope, and verification of a wave form pattern, or some such thing. Over my head.

7. Coil and ignition power transistor

IPT tests good. I haven't checked the coils. Will today. I'm thinking it's unlikely that all 3 coils died at the same time though.

8. Injectors.

As mentioned, got a signal from at least one.

So this is what I'm trying to find at the moment...
While I definitely appreciate any and all input on this vehicle, I'm finding that it's difficult to find a good source of Montero specific information, or a solid Mitsu forum. Lots of Eclipse info, but not so much with the Monte.

I'd like to find a way to test the cam and crank sensor that doesn't involve me buying an oscilloscope, and having to figure out how to use it. I found one site that has a testing procedure for the 3.0 liter Montero, which I'll try today, but I'm just guessing that it's the same as the 3.5 so I won't really know for sure how to interpret my results. On the 3 liter motor, the site I'm looking at says that a bad crank sensor will prevent both spark and signal to the injectors. I've got a signal to at least one injector. Anyway, the sensor is just a magnetic on/off switch, right? Should be the same...?

Also, if anybody happens to know of a good Montero forum, point me in that direction if you wouldn't mind.

Thanks for all the suggestions.

I tested a few things, and found a potential issue with the crank sensor. As I mentioned above though, I don't know how to evaluate my results since the test procedure was for a 3 liter, and I've got a 3.5.

The crank sensor had a good ground, and had 12v to it. Pretty simple up to that point. The website I found says that when the engine is turned by hand, the sensor should send a signal on and off, and that signal should register on the meter as 5v for on, and 0.1v for off. On my vehicle it registered 2.35v for on, and 0.05v for off.

Easy to say it's bad, but I don't know if the 3.5 sensor operates within the same specifications as the 3.0

Can anybody verify if this is appropriate values for a 3.5? I hate to just throw money at parts and hope the problem gets fixed.

Any input appreciated.