I have a 2004 Chrysler town and country (3.3) with 160,000 miles. I got a p0303 code- misfire on number three cylinder. I replaced the plugs, wires, coil pack, and #3 fuel injector. I also did a compression check with a cheap (harbor freight) comp tester. One time they seemed all about 160 lbs and another time the number three seemed low (100ish). Not sure if the cheap tester was the issue or if the cylinder reads different at different times? Battery power was running down as well from cranking. When I did the compress test I pulled all the plugs and turned the engine over. Should I only remove the plug of the cylinder I'm testing? Should I have it running? Any other thoughts?? Help before I pull the rear head and run it to the machine shop! Thanks

 

check the fuel injection wiring harness connector for damage near the power steering reservoir (drivers side). The wires get damaged from the location near the exhaust manifold.
You can buy a repair kit to fix it, if it is damaged.

On the later models it runs on the other side and should be OK..

 

Thank you. I did check today and indeed it does run under the exhaust on the drivers side, although I can't see any damage. Does the connector go bad, or do the wires melt? Any way to test it?

Today I also checked the compression with a better quality tester. I am able to get 190 lbs on all cylinders. The only weird thing is, on the #3 cylinder (the problem one) I get a different sound from the others. When I test the other cylinders I get a rythmic sound and a feel when there is compression. When I do #3 within a 15 cycle crank I get about two or three that just doesn't sound or feel like the others. Sort of weak sounding. Could I be getting a lack of compression on just two or three compression strokes?