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john aka eauto
john aka eauto, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 15575
Experience:  16 years ase certified
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Have 2002 Montero limited, 190,000mi, p0300 code. Runs rough

Customer Question

Have 2002 Montero limited, 190,000mi, p0300 code. Runs rough sometimes with a service engine soon light. Installed new small Catalytic convertors, all new O2 sensors (4), new EGR valve, new battery. Input side of all three coils are 1.3 to 1.4 ohms. I am going to call Autoenginuity tomorrow and see if I can get a Mitsubishi enhanced download as I am not home to wait for mailed disk. Should I just go ahead and get three new coils and proceed from there?
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  john aka eauto replied 1 year ago.

I would start with coils

ITEMSSTANDARD VALUELIMIT

Ignition primary coil resistance at 20 deg C (68 deg F) Ohm0.74 - 0.90-

Ignition secondary coil resistance at 20 deg C (68 deg F) kOhm20.1 - 27.3-

Resistor wire resistance kOhm-Maximum 19

...................

  • Component Tests and General Diagnostics

IGNITION COIL CHECK

  1. Measurement of the primary coil resistance Measure the resistance between each ignition coil terminal.

Standard value: 0.74 - 0.90 ohm

  1. Measurement of the secondary coil resistance Measure the resistance between each ignition coil high-voltage terminal.

Measurement points

  • Number 3 and Number 6 cylinder side coil... A coil
  • Number 1 and Number 4 cylinder side coil... B coil
  • Number 2 and Number 5 cylinder side coil... C coil

Standard value: 20.1 - 27.3 kohms

Customer: replied 1 year ago.
24.6k avg on all three coils at plug side.
1.4 ohm at input side, but if I put MM to sound on continuity, the numbers were .001 area
Expert:  john aka eauto replied 1 year ago.

Please remember to only rate my service when you are satisfied. IF you feel the need to rate "Poor Service" or "Bad Service", please stop and reply to me via the REPLY TO EXPERT button with the issue you have. I will be happy to continue further and do everything I can to provide you with the service you seek.

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Customer: replied 1 year ago.
The place I bought it from, (wife did when I was away), said they did a tune up, I see there are 4 of 6 new plug wires installed of which they have 90° boots not straight at the coil so I am now thinking there will be more problems to discover. To install new plugs and wires the intake plenum needs removed, I am not in a place to do that, so trying to see if I can get it going with new coils maybe, I have a new fuel pump and filter, thinking maybe have fuel pressure problem causing random misfire, but am now thinking the coils are bigger problem, would the high input value but acceptable output value of each coil still be grounds to replace all three coils?
Expert:  john aka eauto replied 1 year ago.

yes ohm tests are not 100 percent on a coil electrical parts usually act up when hot...id start with a good quality coil and plug wires

Customer: replied 1 year ago.
Will order them from a local autozone now and let u know tomorrow the results.......that was my plan from all my reading before contacting this site, thanks.
Expert:  john aka eauto replied 1 year ago.

let me know

Please remember to only rate my service when you are satisfied. IF you feel the need to rate "Poor Service" or "Bad Service", please stop and reply to me via the REPLY TO EXPERT button with the issue you have. I will be happy to continue further and do everything I can to provide you with the service you seek.

I am not paid unless I get a rating of 3 to 5 Stars/Smiley Faces. If I have helped you with your question, please give me an appropriate rating so that I get credit for helping you

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