my truck has 150,000 miles on it. No recent changes made. Was driving it the other day and lost power. the next day I started pulling plug wires to find the miss. When I found it I pulled the plug and the end of the plug was bent and touching the electrode and chipped the porclian. I replaced the plug with a new one, still missing. Plug was fine,no damage, getting spark,plug had expected amount of gas from starting. So I did a compression test and it barely moved off 0. I pulled the valve cover and the valves appear to be functioning properly. I never heard a thing and I still can't with a stethoscope. Oil is clean,no water.
bent valve??
broken ring???

Help please!

 

Sounds like maybe a broken rod if the end of the plug was bent put a dowel into the cylinder that has no compression and see what happens it probably won't move when you turn the engine over

 

Good idea. I figured it would have made alot of noise. I will try that tomorrow and let you know what happens.
Thanks,
Robert

 

More than likely a chunk broke out of the top of the piston and ended up hitting the
plug. The top ring lands get loose and they break, the rings bust from lack of support. If you pull the pcv out you will see blowby.

 

That makes more sense than a broken rod being there is no knock. I will check that as well in the morning. Thanks,

Robert

 

We all could use help with "strange misses" -and Mrs.,Too