DREADED MISFIRE on 2005 Ford Expedition

I GOT A P304 AND COULD HERE THE MISFIRE ON 4. I REPLACED THE PLUG AND COIL. MISFIRE STILL HAPPENING. I ALSO HERE ONE ON 7, AFTER SPEAKING TO ANOTHER EXPEDITION OWNER. PRETTY SURE THAT IT WAS THERE WHEN THE WOLE THING STARTED. SO BASICALLY, I HAVE A MISFIRE ON 4 AND 7 AND IT ISN'T THE PLUG OR COIL PACK. FROM WHAT I UNDERSTAND FROM THE AUOT PARTS STORE GUYS, IT'S A COMMON DEAL. PLEASE HELP. I DON'T HAVE A LOT OF DOUGH TO KEEP THROWING AT IT. THANKS

by in Ringgold, GA on April 04, 2009
3 answers 1 comment
ANSWER by on April 05, 2009
Try changing one of your coils with another cylinder, clear the code(s) and see if the misfire and code changes. Actually I have replaced a lot Ford coils. Remember, the parts store guys/gals mean well but they aren't trained and seasoned techs. If this doesn't help let me and I will give another thing to do. The next thing to check is the intake manifold gasket and the manifold it self. You have a misfire code on each bank i.e. P0304 and P0307, so that means there is a problem for both cylinder banks. I really doubt that injector flush will help much. I do Emissions work in N Calif and have to deal with misfiring Fords to get them to pass Smog. Have some one check your Fuel trim numbers to see if the engine is running too lean, also a sign of a vacuum leaking manifold/gasket.
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ANSWER by on April 07, 2010
clean the injectors/ shop air over a cleaner canister- gm top engine cleaner recomened, and then z-max micro lube with gas 50 50 for final will clear it right up.tom from palmer automotive palmer alaska
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ANSWER by on November 12, 2010
were having the same problem.what i found out was if you take the sparkplug out thats misfire and see if its soaked with fuel.the gap is to wide.thats what i found out.if the cylinder is wet with fuel it will trigger alots of codes.
COMMENT by on November 13, 2010
These vehicles use double Platinum plugs, and you should never touch the gap, because when you do you crack the Platinum tips. If the gap is too wide, you need to replace the plugs. This is taught in the factory classes. dandd
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