06 Liberty Cylinder 6 Misfire

[Lostsheep]

I need some help -
Have had a cylinder 6 misfire.
I have done the following with the EDC returning
spark plugs
coil pack
fuel injector
crank sensor
cam sensor
compression test (200-210 on all cylinders)
New PCM

The EDC keeps returning. Any ideas or suggestions would be greatly appreciated.

 

[libertybob]

Misfire

Have you checked the wiring going to coil #6? Autozone has a loaner kit with electric lights that plugs into the wiring harness connector for coils and fires the light when the PCM tells the coil to fire. If the wiring harness to coil 6 is shorting out, it would not signal coil 6 to fire. Plugging in the test light to the #6 connector will tell you if you are getting a signal to fire . Also, is the plug wet when you get the misfire? If the misfire is constant the plug should be wet if you are getting fuel. If the misfire is intermittent, the plug likely won't be wet. If you can plug in a test light to the injector wiring harness, this would test for a signal to the injector to open. With all you have done, I would check the coil harness first and then the injector harness. With good compression, either lack of fire or fuel is causing the problem. Suspect fire first.

PS: Check the coil and injector wiring connectors for corrosion, especially if the misfire is intermittent. Corroded/contaminated connectors are a common cause of intermittent operation. An electric contact cleaner in spray can is something I keep handy.

 

[uss2defiant]

1. move the coil #6 to a different location and see whether the problem follows

2. do a coil resistance measurement

Checking the resistance involves 2 parts:

1. primary resistance
-measuring the resistance between the two pins in the ignition coil connector
primary resistance between 0.6-0.9 ohms

2. secondary resistance
-measuring the resistance between one of the connector pins to the spring inside
secondary resistance at 6k to 9k ohms