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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8594
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitsubishi Montero RS: Doug, I have a 91 Montero 3.0 No spark.

Customer Question

Doug, I have a 91 Montero 3.0 No spark. The guy I got it from said it would start and run and you could drive it all day. But as soon as you turn it off its not going to start for a day maybe two. The other guy replaced the comp box with a used one. still no good. I cant get spark at any time right now. it has 136 thousand on it . has good compression, timming belt is ok distrib is turning. Is there something that is common on these?
Submitted: 2 years ago.
Category: Mitsubishi
Expert:  Doug replied 2 years ago.
You need to check to see if you have injector pulse before doing anything else. If there is no injector pulse while cranking, you need a new crank position sensor (built into the distributor).
If you DO have injector pulse, this means the computer is seeing the RPM signal and is likely trying to spark but can not. In this case go to the PTU ("ignition module") and check your voltages there... unplugged you should have ground on pin 2 (black) and you should see voltage pulsing on pin 1 (white) while cranking. If you do not, revisit the computer as your suspect.
If you do, then plug the PTU back in and unplug the ignition coil. Check for GROUND pulse on pin 1 (white/blue wire) while cranking. If you do NOT have ground pulse while cranking (but previous tests were OK), then the PTU is bad. If you DO have ground pulse and there is no spark, the ignition coil is bad.
This all assumes no rodent damage to wiring or anything like that of course. If you see anything unusual with the wire condition, pursue that first.