P0306. I KNOW IT'S A #6 CYLINDER MISFIRE?

  • Tiny
  • jvrbka
  • 2004 Chrysler Town and Country
  • 121,000 miles

My wifes Town and Country has check engine light on. The code it p0306. I know it's a #6 cylinder misfire, but I can't figure out why it is misfiring.

The engine light is on. P0306. I've changed the plugs, plug wires, coil pack, and fuel injector, and the light is still coming on. I don't know where to go from here. I thought maybe fuel pressure was low and because the #6 cylinder is the last one on the fuel rail it's not getting enough pressure, but I can't figure out how to test it.

There is no scrhader valve anywhere. I've had the fuel rail out when I changed the injector and there isn't a valve on it to hook a fuel pressure gauge to. How do you check fuel pressure on these engines and is there any other ideas as to what could be causing the misfire?

Thanks!

Thursday, October 4th, 2012 AT 3:35 AM

15 Answers

  • Tiny
  • saturntech9
  • Expert
  • 28,864 posts

Does it missfire constantly or just sometimes.

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Thursday, October 4th, 2012 AT 4:04 AM
  • Tiny
  • caradiodoc
  • Expert
  • 25,308 posts

Fuel pressure can't be any different at the various cylinders. All the injectors are fed from the same large tube. I have to guess at the engine size. The 3.0L doesn't use a fuel pressure test port. You pull the supply hose off and insert a tee with a fitting.

You might consider a compression test. Chrysler typically has extremely little trouble with injectors. The spark plugs and wires normally solve 95 percent of misfires, injectors and fuel pump about one percent.

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Thursday, October 4th, 2012 AT 4:07 AM
  • Tiny
  • saturntech9
  • Expert
  • 28,864 posts

Thats where I was going is compression thats why I asked if it miss fired constantly?

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Thursday, October 4th, 2012 AT 4:13 AM
  • Tiny
  • jvrbka
  • Member

It's a constant misfire. The engine is the 3.8l. So the next step should be to check compression?

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Thursday, October 4th, 2012 AT 5:19 AM
  • Tiny
  • saturntech9
  • Expert
  • 28,864 posts

Yes if its constant I would check the compression.

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Thursday, October 4th, 2012 AT 5:34 AM
  • Tiny
  • jvrbka
  • Member

If the compression of that cylinder is low, what do I do after that?

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Thursday, October 4th, 2012 AT 10:49 AM
  • Tiny
  • saturntech9
  • Expert
  • 28,864 posts

I would check all the cylinders compression and if only the number 6 cylinder was low.I would suspect a valve issue. Then I would do a cylinder leak down test to pinpoint if that's what it is.

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Thursday, October 4th, 2012 AT 3:05 PM
  • Tiny
  • jvrbka
  • Member

Ok. I'm going to try and get a compression gauge tonight.

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Thursday, October 4th, 2012 AT 3:07 PM
  • Tiny
  • saturntech9
  • Expert
  • 28,864 posts

They rent them at auto zone.

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Thursday, October 4th, 2012 AT 3:51 PM
  • Tiny
  • jvrbka
  • Member

Finally got a compression gauge that works. The first one I got had a small hole in the hose, so I had to take it back. The #6 cylinder only had a psi of about 100. The others were around 150. I also poured about a capful of oil in the #6 plug hole and it was still reading about 100 psi.
Where do I go from here now?

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Saturday, October 6th, 2012 AT 3:54 AM

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