Broken Valve Springs, Misfires and PCM problems with Jeep Liberty 3.7V6 2006


#1

I have owned a Jeep Liberty since it was a new lease and I purchased it outright at the end of the lease.
The car currently has 95K miles on it.
Its had all factory scheduled maintinance and I have use synthetic oil since the first oil change.
In January the car started running poorly with little power and the check engine light came on.
In scanning the OBD I found the number three cylinder was misfiring and after some checking I found the cause was a broken broken valve spring on the exhaust valve which dropped the valve into the cylinder and damaged the piston, valve guide rocker and lifter etc. I pulled the engine and removed the head which were refurbished at a engine machine shop (All springs replaced, valves ground and defective valves and lifters replaced. I reassembled the engine and replaced the piston, spark plugs, fuel injectors, coils, timing chains and guides, water pump, hoses, belts and gaskets. I also replaced the four oxygen sensors and the oil pan (the pan was so rusted and thin and I could poke my finger through it.
After the engine was reinstalled the car ran fine for about 1000 miles and than it started to run poorly again. An OBD check called out cylinder 5 misfire and again after a little checking I determined the PCM was defective.
I called up my local Jeep dealer parts man who I gotten to know quite well and he quoted me the part price and informed me that the dealer service department would have to replace and reprogram it but they first insisted on diagnostic testing. When the car was returned they charged me $216 for the labor and testing plus the price of the PCM and $21.60 for shop supplies (must have used a lot of rags).
On the way home the car started to idle rough and the check engine light came on again. I returned the car to them and they have had it for the last two weeks. I got a phone message that the car is fixed and I must go pick it up.
My questions are:

Should I pay them anymore since the PCM repair. They supposedly guarantee their service work for 12K mi or 12 months. When I called about the Jeep I got various comments of Jeeps won’t run right with Bosch Platinum Spark Plugs, the engine was missed wired (Hard to accept since the harnesses are all cut and taped and fit well, you would have to splice in wire to get them plugged into the wrong coil or injectors. It will be interesting what lame explanation they will come up with this time.

Are these type of part failures common in Jeeps?
I’ve previously had to replace the transmission lines, and one of the rear door operators. I’ve never had this many problems in so few years and miles in any of the 50+ new and used cars and trucks I have owned in my life.


#2

Sounds like a problematic vehicle to me and maybe the last rough running episode has nothing to do with any prior ones.
They guarantee their diagnostic and PCM replacement for 12/12 but that doesn’t mean everything else attached to the vehicle.

From the description of the original problem, an oil pan rotted out so bad on an '06 a finger could be pushed through it, etc, etc the first thing I would have done is run a compression test on all cylinders and and possibly consider scrapping the engine for another one depending on those results.

There’s a lot of questions about this vehicle from the onset of the original problem and just my opinion here, if the dealer was aware of the entire situation from the get-go they should have probably refused to even work on it.
Getting in the middle of something like this often leads to a lot of problems.

You pulled the engine and repaired it, diagnosed a PCM, etc. so why did you take the vehicle back for a CEL, rough running problem? What was your diagnosis at that point, if any?