My '05 fx4 has 169,000 miles on it and recently had had codes throw that were 3rd and 4th cylinder misfire. I changed 3 and 4 and coil packs. Truck ran fine for 5000 miles then check engine light just came back on. throwin 3rd and 4th misfires again, only this time motor is ticking very bad and white smoke is pouring out of exhaust when I rev it up. Also when I tried to pull it forward it would barely creep along then go. Is my problem a piston problem? any info would be great, maybe keep me from goin and buying new engine

 

The white smoke could be from coolant or raw gas, usually coolant. If the head gasket is shot then coolant is entering the cylinders and causing a missfire as well as the smoke. A intake valve follower off can keep the valve closed and the fuel will not burn in the combustion chamber. The raw gas burns in the exhaust system creating white smoke. Pull the sparkplugs in cyl 3&4 and check them for coolant or gas. Is the coolant system getting overpressurized? Check or have the degas bottle checked hydrocarbons.

 

Thanks for the input.