have the 4.7V8 2wd, have p0300 and p0308 codes that won't clear
Truck runs well, maybe slight hesitation under power.

Have replace the plugs, coil pack #8 and used a can of Techron fuel cleaner.
Truck has been well maintained with 72K.

Dealer wants to pull the head. Seems unwarranted at this time.

Anyone? Thanks

 

I'm assuming they have a reason to want to pull that head, maybe didn't pass a compression test?

 

Sorry Jaded, it was because #8 showed only 100#'s on compression test.
No record of other cylinder readings.
I read that a valve spring may have broken and that some have repaired it without removing the cyl. head.

 

So, let the dealer fix it then.

 

If you're uncertain, do your own compression test or get a second opinion.

 

soooo I pulled plug #8, although it was changed ~2k miles ago it was black and fouled.
Used a compression tester, it screws into the head but seems to swivel easy so its not certain how much its threading into the head / first reading 125#

Pulled the adjacent plug, it was the burning fine, light brown color, and that cylinder tested 150#, decided to repeat the test on #8 and this time also 150#

Clearly the "dealer" who saide #8 was at 100# was wrong and its almost certain the rings, piston, and valves are in fine shape.

Plan to pull the throttle body and soak it overnight in carb cleaner as this seems to be important on Dodge Chrysler engines (at 72k), don't think it is possible that this would affect only one cyl. selectively.

Anyone have other useful suggestions?

Thanks

 

check your down stream 02 sensor, could be crapping out, also run a tank or 2 of good hightest gas and rip the crap out of the truck. could be a lot of carbon built up that needs to be blown out, also what plugs did you use?

 

Plugs were changed twice in 4k miles by two different dealerships going by receipts that came with truck. Removing throttle body today for cleaning and hopefully to check sensors. Will report back. Have some Sea Foam, will probably use it after cleaning Throttle Body. Current plugs are Champion installed at dealership, the guys who mis reported on low compression.

 

If everything else checks out, I'd pop the valve cover. It is possible to have a problem with the rocker arms or camshaft that will cause a misfire along with good compression readings.

 

Sounds like good advice since cleaning the mildly carbonated Throttle Body did nothing.
Also wondering about TPS and MAP sensor but assume they would have their own specific code.