Ford Enthusiast

[Mike J.]

I highly suggest you get a repair manual. It will help you diagnose your problem.

Your codes are telling you that you're having trouble with one side of the engine, cyl 4-6. My first inclination is that your ignition pack is bad. The Hanes manual gives directions on how to test the primary and secondary coils.

The firing order is 1-4-2-5-3-6. Notice anything here? The side with the trouble is after the good side fires. So, if the ignition pack isn't sufficiently charging before the next cylinder must fire, you'll get a miss fire. Also, two spark plugs are being fired at a time, one on the intake compression stroke and one on the exaust compression stroke. So, with first number the power piston and second number the exaust piston, here's how it's firing: 1&5-4&3-2&6-5&1-3&4-6&2. When you crank the engine the Camshaft Position Sensor always finds and fires cylinder 1 first. It does this from the 36 tooth crankshaft pully. The missing tooth (#37) gives it the reference it needs to send to the computer to know where each cylinder is located. So, a bad coil will always be symptomatic in the same sequence.

I doubt that the Camshaft sensor is bad, since it knows where cyl 1-3 are located.

Finally, there could be some other common error in the intake to the cyl 4-6 bank. The lower compression could be an indicator of the problem. Posibly a bad intake gasket. I've found previously a problem in one bank is due to water getting into the intake and fouling the plugs. Check the vacuum with a guage, a rocking vacuum needle will indicate a leak, which would also cause lower compression on the effected side.

Finally, check your cyl 4-6 exhaust manifold/pipe for a leak or blockage.