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P0306 code--help


jbruno

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How many miles on your Journey? Plugs are due @102,000 miles according to the maintenance schedule set forth in the manual, but honestly they rarely last that long. Could be ignition, fuel or mechanical issue. Remove the spark plug to inspect its condition. You can try switching ignition coils with the adjacent cylinder when you remove the plug to see if the misfire follows the coil. If the MIL comes back on for the same cylinder, you can try swapping the injectors like you did with the coil to see if the misfire follows the injector. If it stays on cylinder six, then the cause is likely to be mechanical (usually a burned valve).

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I have 85,000km on the vehicle. I swapped the ignition coil with #4 cylinder and I still got the P0306 code. I pulled out the #4 and #6 spark plugs and they looked ok but the #6 was black and the #4 was not. I swapped the two and after clearing the codes, I got the P0306 code again. I wanted to try and remove the #6 wiring harness on the injector but I couldn't figure out how to remove the harness and I didn't want to break it. Any other suggestions?

Thanks

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This may help:

14 - Fuel System/Fuel Injection/INJECTOR(S), Fuel/Removal 3.5L 95986.jpgWARNING: The fuel system is under a constant pressure (even with the engine off). Before servicing any part on the fuel system, the fuel system pressure must be released.1. Release fuel pressure, (Refer to 14 - Fuel System/Fuel Delivery - Standard Procedure) . 2. Disconnect and isolate negative battery cable at battery. 3. Remove the upper intake manifold, (Refer to 09 - Engine/Manifolds/MANIFOLD, Intake - Removal) .

97750.jpg 4. Disconnect the quick connect fuel line from the fuel rail.

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NOTE: Mark fuel injector electrical harness connectors with correct corresponding cylinder numbers. 5. Disconnect all fuel injector electrical connectors (1) from fuel injectors (2).

64515.jpg 6. Remove fuel rail mounting bolts from fuel rail and lower intake manifold.

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NOTE: Gently rock the fuel rail and injectors back and forth to loosen the seals on the fuel injectors from the cylinder heads.CAUTION: Do Not use excessive force or prying tools to remove fuel rail and injectors. Damage to the fuel rail and injectors may result.7. Lift fuel rail straight up off of the cylinder heads. 8. Drain any excess fuel from the fuel rail into an approved fuel storage container.

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NOTE: When replacing individual fuel injectors, each fuel injector must be installed to it's original position. Mark or tag each fuel injector to identify the correct cylinder. 9. Remove retaining clips (5) from fuel injectors (2) at fuel rail (4).
Edited by Journeyman425
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  • 2 years later...

Journeyman425, just received similar codes, P0203, P0303.  In your experience on working on the 3.5L (Journey SXT 2wd), do you suggest going right for the fuel injector or doing step by step - fuel treatment, spark plug, plug wires, then fuel injector?

 

Thanks in advance, and thanks for the above diagrams.

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  • 3 weeks later...

Do as journeyman says...

 

Cyliner misfire 3.5L V6?  Try Seafoam, spark plugs, swap coil packs, swap or replace injector. If they don't help do compression check...(internal valve problem)

 

I am doing the same process.  I replaced spark plugs and get the same P0305 code still... 

 

I expecting the worse with a valve problem...

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On ‎1‎/‎4‎/‎2017 at 5:30 PM, rediranch said:

Journeyman425, just received similar codes, P0203, P0303.  In your experience on working on the 3.5L (Journey SXT 2wd), do you suggest going right for the fuel injector or doing step by step - fuel treatment, spark plug, plug wires, then fuel injector?

 

Thanks in advance, and thanks for the above diagrams.

How many miles on your 3.5? If you have P0203 and P0303, that indicates fuel injector control circuit and cylinder misfire #3. Service Manual possible causes for P0203 are as follows:

Possible Causes

FUEL INJECTOR 3 CONNECTOR OR WIRING
(F342) FUSED ASD RELAY OUTPUT CIRCUIT
(K13) INJECTOR 3 CONTROL CIRCUIT SHORTED TO VOLTAGE
(K13) INJECTOR 3 CONTROL CIRCUIT SHORTED TO GROUND
EXCESSIVE RESISTANCE IN THE (K13) INJECTOR 3 CONTROL CIRCUIT
FUEL INJECTOR 3

POWERTRAIN CONTROL MODULE (PCM)

 

 

 

 

You can swap two of the injectors side-by-side and see if the problem follows the injector. If so, replace it and the associated spark plug. If the misfire remains on #3 fhen follow the diagnostics as outlined above.

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