Hey everybody. As you can tell from the title I am a noob here and I have a problem. About a month ago, my wife and I bought a 2004 Pacifica. It was running fine but it did have an intermittent misfire on the #4 cylinder. Last week I was driving to see some friends when the timing belt broke. I had a local shop fix it and replace the water pump, belt tensioner, and some seals while he had the timing cover off. $1700 later, he calls me and tells me the the #4 cylinder has a hard misfire. Unfortunately, the timing belt repair sucked all my available funds (and then some) so I couldn't afford to have him diagnose the problem. He did tell me though that when the timing belt broke, none of the valve stems got bent.

So I limp it home. It was due for some plugs so I replaced those. The plug on #4 was pretty dirty with oil (I'm assuming from not firing). No luck - still misfiring. I changed the ignition coil - no luck. I swapped the fuel injector with cylinder 2. The misfire was still on #4.

So this is where I am. The next thing I am going to do is try to trace the wiring back and see if I can find any issues there. Any advice would certainly be appreciated. Thanks,

Eric

 

So I just put a vacuum gauge on the plenum. It was bouncing all over the place between 11 in Hg and 16 in Hg at idle. At 2000 rpm, it was still jerky between 17 and 19 in Hg. I guess that's a big clue that something is going on in the engine itself. Crap. It may have to sit until payday at this rate. Anybody have any ideas what I could check next?

Eric

 

Hello, I have the same problem in my 2004 Chrysler Pacifica 3.5L
and I have a misfire on #4, I have replaced the Injector sparkplugs, even the coil. But I keep getting back P0304 on cylinder #4

Did you ever find the Problem in your car?