This is a new to me at 150k miles I am trying to being her back to 100%

I am getting an intermittent CEL light for a P0304 - cylinder 4 misfire. The CEL light is random it will be on for a few days then it will turn off .

I just got my BCM replaced by my local dealership they checked out all the cylinders for me and they said that #4 was giving them inconsistent compression tests of 130psi to 180psi at random with a recomendation to replace the head.

The whole random compression thing is really bothering me I dont understand how a cylinder can have this issue.



UPDATE 8/21

I put the recommended amount for Mystery Oil with the engine oil and ran for 200 miles
I ran a can of upper end seafoam cleaner

The CEL for P0304 is still turning on and off around every 4 days, engine seems to run a bit ruff.

I am close to removing the camshaft cover so i can take a look at the upper end. If any one has any thoughts i would appreciate any help I'm sorta stuck right now.









looking for any input

2006 stock h3
150,000miles
new spark plug
New fuel injectors
Checked coil pack
Checked wires to cylinder

 

had the same on Cyl 3, replaced the ignition coil of cylinder 3 and no issues since then.

 

2006 had head issues. they where recalled. a coil will not fix erratic compression

 

I believe my vin # is past the lot of bad heads, I dont believe there was an official recall that would apply to me now?

I am still in question what mechanical issue would cause an intermittent compression instance .

 

Defective heads would have been replaced by now.

DO MORE RESEARCH, ONLY USE TOP TIER FUEL.
TOO LATE...
NOW YOU NEED TOP ENGINE CLEANER, TO REMOVE THE CARBON DEPOSITS!
DIY, OR TAKE IT TO A SHOP FOR AN INDUCTION CLEANING. ADD A CAN OF SEAFOAM TO THE TANK AND ENGINE. USE TOP TIER FUEL, ETC.. DECARBONIZE, TO FREE THE STICKY VALVE:::::::::>>>16-NA-383

 

I had the misfire on 2 and 4 and all I did was just change the cylinders and all good.

 

WTF did you change?????

 

sorry just saw that. I change the ignition coils and everything worked fine.

 

Awesome advice and seconds my thinking, I forgot to add that this is a new to me truck and I am dealing with past undoing to her .