2004 Pacifica FWDwith just shy of 100K on it.
In and out of the dealership and a local shop, that I trust, for the check engine light. Local sent us to the Dealer whofound a wire that needed soldering, light came back on. This time it is rough and at about 3000rpm acts like a rev limiter.
Local shop this time says scanner reads as #4 cylinder mis-firing. Suggests plugs and tune-up, which to me sounded logical at this mileage and never having been done, except #4 requires a deal of work to accessI am told.
He did an oil change first, and went to start it. "System Imobilizer" on the screen. Dealer tells him lock it up and let is sit for 24 hours, the computer may re-set itself, "happens all the time".
It didn't re-set, so tow to dealer.
They say possible PCM but can't determine, no power. Two days later they find a short between the PCM and something else?.
Fix the shorted wire. Today the dealer says an aftermarket remote car starter that has been in the car two years, confused the system, and shorted out a "something sweep", which in turn fried the PCM. They said this happens all the time with after-market devices.
They showed me a bag of parts and wires, containing the sweep and remote starter parts, etc., but NO PCM. Explanation was that it needs to be exchanged and sent back.
- Does this sound correct? A functioning remote starter can all of a sudden cause this to happen?
- How do I know they actually changed out the PCM?
- The #4 cylinder problem is still there. My mechanic had saidbefore this happenedhe thought it may be the fuel injector, but those need to be done in sets. I am reading on here that it may be carbon on the exhaust valves. What do I do?

 

I'm not sure about your current problem but you should have your timing belt changes if you haven't done so yet. 100k is when it's supposed to be done.

 

you can look under the front bumper cover on the drivers side right in front of the tire and see if the pcm looks new. pcms do have to be sent back they are usually reman, as far as the misfire there is a tsb to rotate the exhaust valves and install new valve spring retainer locks to help the valves rotate at lower speeds, decarbonize the combustion chamber and inspect and/or replace the map sensor. basically what i would try is decarbonizing the combustion chamber and they driving the vehicle harder and making sure the map is the new style, this has worked for some customer i know. also the tune might not be a bad idea since it has 100,000 mile plugs...fuel injectors can be replaced one at a time!

 

My daughter's has electric problems since day 3. It's the way they run the wiring she had part of harness replaced then some wire keeps it from starting 3 times last time was moved and fixed right now it just got plugs and coils did not fix dealer broke a lot of wires and bolts check ground wires driver frame 3 studs 2 rings have 12 wires each I found one wire each crimped but no copper took rings off studs and all but one of 24 ground wires pulled right out without effort. So I would check there next.