Alfa 156 2.0 JTS spark plug / compression problems
First a short history of the car-- model year 2004-- friend of my wife's bought it used in 2008. Already it had some sort of engine problem, as evidenced by the lit check engine light, but he got duped by the used car dealer who chalked it up to the cold of winter! At some point, he drove it to Italy on too little oil and it had to have its cam shafts replaced (maybe other things, I'm not totally sure). In 2010 he gave it to my wife, as he had moved on to an Aston Martin.
It served us until August 2011, when its prior troubles accelearating had become rather pronounced and I, having only had experience fixing a Honda Accord with the helping hand of a Haynes manual became rather afraid at all the possibilities behind "Cylinder 1 misfire" and complex engine rebuilds without having even the rather meager collection of automotive repair tools I was used to at my mother's home in the U.S. Plus having an infant and worried about the possibility of sometime needing to race to the hospital and needing a car to pull a trailer pushed me to buy another car for us, with the intention to get around to fixing whatever was wrong in the Alfa.
Moving forward to last summer (2012), the Alfa had just sat for a year in the driveway and a mechanic friend of mine decided he wanted to have a look, and much to my shame discovered the main problem to be old spark plugs! As it was there were some other things to fix on it (holes in exhaust) and we were in the U.S. most of last winter, so we didn't get it all straightened out and driving until this May.
At first it was driving really well, but slowly this problem with not accelerating well has come back, so today I pulled the spark plugs, and found that two of them from cylinders 2 and 3 were totally burned away. I also did a compression test:
Cylinder 1*: 195PSI
Cylinder 2: 155PSI
Cylinder 3: 175PSI
Cylinder 4: 200PSI
The engine was warm. I added (per the instructions on my compression tester) a spoonful of oil to cylinders 2 & 3 and checked again and they got 200 and 210 PSI respectively. My understanding is that this shows a problem around the piston rings.
Would spraying one of those penetrating oils possibly help in this case? I have recollection of the directions on a can of Knocker-Loose saying it frees stuck rings...
Is the low compression in these cylinders the reason the spark plugs deteriorated so badly?
I replaced all of the Brisk spark plugs with Bosch spark plugs having a more conventional electrode style.
Does fixing this mean taking the engine out of the car completely, and is there any sort of manual showing the steps needed to do it?
Thanks for any advice,
* I'm assuming cylinder 1 is the one next to the timing belt, and then counting up from there.