Bad CPS and misfire

[badkarate]

I own a 2003 Sport Trac 4wd with the 4.0L non flexfuel. On the drive home from work yesterday the check engine light came on, and the vehicle was running rough. I took it to autozone, had codes pulled, and it said the crank position sensor was bad, and there was a misfire on cylinder 3. I replaced the CPS, and that got rid of the check engine light. The truck is still running rough at idle though. Since both issues showed up at the same time, I assumed that the misfire was caused by the bad CPS. The only thing I cant think of is that there is a relearn period for the sensor that hasn't been completed, since I have only driven about 7 miles since replacing it. Any suggestions?

 

[badkarate]

No ideas? How about the ignition coil? Also self bump

 

[ncranchero]

Has it thrown another code? Did the P0303 misfire code go away? If not I'd say wires/plug. What was the original code NUMBERS, you know?

 

[2000StreetRod]

harmonic balancer

Make sure that a separating harmonic balancer did not cause your crankshaft position sensor to fail: Harmonic balancer failure

I doubt that there is a long relearn period. Your engine may still be misfiring but not enough times to set the CEL.

 

[badkarate]

Made a mistake on the code I stated previously. The codes I received were a P0304 and P0316. Currently the check engine light is off. I went to autozone 15 minutes ago, and there were no new codes to pull, and the old ones were no longer there.

 

[2000StreetRod]

misfire codes

P0304 Cylinder 4 Misfire Detected
P0316 Misfire Detected On Startup (First 1000 Revolutions)

Engine misfire procedure

 

[badkarate]

All fixed. The plug wire was pretty crispy towards the plug side. Replaced it and all the problems went away. Thanks for the help folks.