no ignition!!

[tenderfoot1877]

for some reason, I am not getting ignition from the #4 and #6 cylinders. I have changed out the cap, rotor, plugs, plug wires I am getting fire all the way to the spark plug, but for some reason no ignition is happening in the cylinder. I don't know if the valves for those two are not opening all the way or what. I have great comression, just no ignition. So right now Im just running on 6 cylinders. Please send me your opinions.

 

[opfor2]

Well I don't think the valves not working would cause the cylinders not to fire. Compression has nothing to do with the ignition in our older trucks. Did you double check the wires with a DVM ? You might have bad wires.

Dan..

 

[dyeager535]

I *think* what you are saying is that if you pull the plugs and crank the engine over, you can see the plug itself sparking?

If the valves are in some way not working correctly, certainly the cylinders will be "dead". Unless valves are stuck OPEN, you will still have compression, but the cylinder won't work right if the exhaust or intake isn't opening. Intake not opening (in my personal experience) leads to oil being pulled into the exhaust, which eventually starts to produce smoke.

However, under compression you can have all sorts of problems if the plugs or wires aren't up to par, still swap plugs/wires between cylinders you know work to positively eliminate that as a possibility.