Mechanics

MY WIFES 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.

2004 Chrysler Town and Country • 121,000 miles

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 schrader 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!
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Jvrbka
October 4, 2012.




Does it missfire constantly or just sometimes.

Saturntech9
Oct 4, 2012.
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.

Caradiodoc
Oct 4, 2012.
Thats where I was going is compression thats why I asked if it miss fired constantly?

Saturntech9
Oct 4, 2012.
It's a constant misfire. The engine is the 3.8l. So the next step should be to check compression?
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Tiny
Jvrbka
Oct 4, 2012.
Yes if its constant I would check the compression.

Saturntech9
Oct 4, 2012.
If the compression of that cylinder is low, what do I do after that?

Tiny
Jvrbka
Oct 4, 2012.
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.

Saturntech9
Oct 4, 2012.
Ok. I'm going to try and get a compression gauge tonight.

Tiny
Jvrbka
Oct 4, 2012.
They rent them at auto zone.

Saturntech9
Oct 4, 2012.
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?

Tiny
Jvrbka
Oct 6, 2012.

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