I have a 05 Ranger 3.0 4wd 118,000 miles that was experiencing a misfire in cylinder 6. The codes read P0300 and P0306. I went and changed the plugs, wires and coil and it didn't help. I took it to the shop and they checked the fuel pressure (in spec) as well as switched the fuel injectors and didn't find a problem with either of those. They ran a compression test on cylinders #4 and #6 and found 130 psi (again in spec). They recommended removing the head and checking all the valves.

My question is if it has compression could the valves still be the problem? I figure if its getting fuel and a spark it has to be the engine itself but how does the compression test fit in? They also quoted me $1700-$2000 for all the work depending on exactly what they find. Is this reasonable? I don't have the time and I doubt I have the ability to do it myself so I need some advice before proceeding. Thanks

 

I hate to say it but... Fix it asap before all pistons "misfire." I did the job myself. It is not an easy job as you need to replace both heads... yes I said both heads. why? Because ford engineers are retard and decided to not use hardened seats on the valves! Normally the exhaust valves are the first to go. If you catch it early enough they can machine the heads where the valve seats and ad hardened seats. If the recess is far to large, they cant machine the heads as if they do they will cut into the coolant channel. Does it suck? Yeah. Mine started with a weird clicking noise when I would "open" up the engine on uphill climbs. I am the Orig. owner, with 119,000 miles on it at the time. I replaced so much **** before I found out it was the valve seats. and around 125,000 almost all the valves had a bad recessing problem. fit it ASAP before you have a dud

Good luck, and If you feel you have the skills to replace them yourself, good luck also :)

 

Thanks for the advice. I went ahead and went and had heads pulled and two of the exhaust valves were the problem.