hey guys in need some help i have a cylinder 8 misfire i have changed the plug wires an put new intake gaskets and plenum gasket my truck has 141000 on it oh and i tested the injector its getting power

 

What year and engine?

How's the spark plug? How about compression?

Check the cap and rotor as well. Some brands are crap.

 

i have not had the compression tested what should it be at and its a 99 dakota with a 5.2l 4x4 ppl have said rings and valve but i know that expensive?

 

Usually, if it's a mechanical problem like the rings or valves it'll affect all the cylinders, not just one. Of course it could be a head gasket or something.

First off, pull the spark plug. Look at it closely for condition. Is it oil fouled? Burnt? The condition can tell you a lot as to how the cylinder is running. It is possible to have a bad spark plug. Also, what plugs are you running?

Don't rule out a bad distributor cap/rotor. There are a lot of junk parts out there nowadays. Look for one with brass posts, not aluminum. Moisture and dirt on/inside a distributor cap can cause a misfire. You might see it as a flash when looking at the distributor, truck running, at night.

For compression, over 100 psi, but more importantly they all should be fairly close.

Start with the plug and cap.