I'm getting an error code of P0203 "Injector Circuit / Open Cylinder 3" when using a OBDII scanner to read my 96 Montero. I don't know if this is a true Mitsubishi code or just a generic code from the scanner.

Either way, sometimes the car shakes when it idles. And only on idle. When driven on the freeway, there is no shake and feels normal. I'm assuming its time to replace the spark plugs and wires. The vehicle has approx 115,000 miles. Last time I changed the plug and wire was around 60,000 miles.

Besides 6 plugs and wires, what else should I change at the same time? Distributor cap and rotor? Anything other suggestions? Thanks in advance!

 

The error code you are getting clearly points to the problem with the fuel injector and not (at least at this time) spark plugs. The #3 injector may have gone bad (burned out) or a wiring harness to it is damage or has a bad connection. Having one cylinder out of six not fire properly will cause shaking at idle. While this is a typical misfire condition, computer does not set a misfire code because it determined that an injector not behaving as it supposed too, so it "wants" you do a dress that first. There is a hierarchy in error codes, so some will pop up first, even though other conditions are present down the line.
I'd recommend you pull all fuel injectors, label them 1-6 for the cylinders from which they came and send them for cleaning and testing. I used service https://www.mrinjector.us/
They tested all injectors upon arrival and cleaned them. If they passed testing for flow rate and pattern, they put in new seals and screens and send them all back. I think if one injector dries not pass, they will let you know and help to find an replacement. I had this done when I rebuild my engine and I'm very glad i did. All injectors in my case tested to OWM specs after cleaning, so I keep running them (267k...) The cost for all 6 injectors was less than it cost buying a single OEM Mitsubishi injector.

 

HunterD
T
hank you very much for the info.....

I'm a bit press for time on this situation though. The vehicle's shaking problem just came up within the last two weeks. The vehicle registration is coming up in less than a month. And in order for me to pass smog, OBDII tests must pass and be ready first. So there's not much time to ship anything out for cleaning.... and then drive around to get the OBDII tests completed..... I'm confident in fixing electronic/ minor electrical and re-wiring issues. Fuel injector removal....I don't know where to start. I have researched on Youtube on Montero replacing spark plug and wiring. And I do have the service manual to the vehicle. But I haven't looked at injectors yet.

During the last 2 smog tests; for OBDII completions, I drove around no less than 600-900 miles extra. I was either re-wiring something in the car or changed the battery, so the memory was gone in the ECU. Now from research and experience, I narrowed it down to a checklist of motions I have to go through to get the OBDII tests completed with the least amount of driving. But it is still nonetheless, very tedious. So that alone will take couple of days.

I think I will have to bite the bullet and see what the dealer tells me on the shaking problem. Keeping your suggestion in mind....I'm afraid how much will the dealer tell me on replacement injector cost.

 

I completely understand your situation. Not fun when you got a fire under your tail... The service I recommended took less than a week to turn everything around. You may want to call thev guy and talk to him about it and your time needs. Fuel injector removal on on Montero is just a few steps further down than changing spark plugs (at least on my Gen 3 model). As far as the drive cycles - you can find information on the web for specific drive cycles. It tells you how to drive to get that cycle completed - certain speed for X number of minutes, then accelerate or decelerate so many times, etc. You can complete specific cycle in under 20 minutes if you follow those directions. If you try to just druve around, you'll hit the needed conditions/counts of operations, but it does take days to get there randomly