Longtime reader first time poster. My truck started to idle very rough. I pulled the codes and I got po308 and po316. First I changed plug #8, the electrode was nearly gone. I have never seen a plug in worse shape. Replaced that plug and fired it up, it still idled rough and threw the same codes. Next I moved the #8 coil pack to the #1 location and vice-versa, still the rough idle and same codes. Then I moved the #8 injector to the #1 location same results. Finally I tested compression in the #8 cylinder and it read 32psi ( not good) everything else read 150 to 160 psi. Squirted some oil into #8 and no difference in compression.The truck is a 2002 with 184,000 miles, it burns a quart of oil every couple weeks but still is in perfect shape. Should I bite the bullet and invest in a remanufactured engine for 2500.00? I put one in my 97 f 150 a few years ago with no problems.

 

Yeah, sure sounds like that cylinder is shot to hell.

When you say the plug was in bad shape, are you saying something hit it? Or was it just oily, and not functioning.

If something hit it, what was it, and where the heck did it go? And, what else did it eat up along the way. Ever find anything in the pan?

 

could be a burnt valve, could be rings, if you want to try to fix it i would start by doing a leak down test to figure out why you've lost compressing in that cylinder. I work on em everyday and in my own opinion its better to put a fresh motor in. Thats what i would do on my vehicle though, i'm paid to give the customer all the options and make them happy

 

The plug resembled the picture of a "pre ignition plug " from the back of a Haynes manual. After taking into consideration the high mileage I have decided to replace the engine. let the fun begin!!

 

Good decisision, post pictures of the journey. LOL

 

Finally got the engine in. Everything back together. Lost only one exhaust flange nut. Started right up ,drove smooth around the neighborhood then when I got on the freeway I wasn't able to go faster then 55 mph. Scanned for codes when I got home and 122 came up ( low voltage on the throttle position sensor) I did remove this sensor to clean the throttle body maybe I damaged it or it wasn't working prior to the engine replacement. let me add that I did remove a lot of broken honeycomb particles out of the passenger side catalytic converter so I new I needed some cat work. I replaced the sensor got rid of the 122 code but still couldn't go faster then 55 then I pulled code 300, 302,303,304. Misfires all on the passenger bank the same side as the bad cat yet no cat codes were thrown . This truck is driven by my wife so I don't know if this lack of speed/power was present before the engine replacement. So I found a company on line that sells direct replacement cat and they are on order. I took off the cats today and tested them with a shop vac blower and sure enough the passenger side is 99% clogged driver side is good but I am going to replace it anyway