5.4 Misfire
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5.4 Misfire
2006 Expodition 145000 miles. New Plugs, Cops, Oxgen Sensor, Speed Sensor, Fuel Filter, Air Filter, Both VCT changed, Mass Air Flow Sensor, Thro ttle Body.
Will Misfire on load. Changed to another new plug and cop on that cylnder then moved to another cylnder changed those then it moved to another. I give up.
Will Misfire on load. Changed to another new plug and cop on that cylnder then moved to another cylnder changed those then it moved to another. I give up.
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If the bolt or nut that secures the ground terminals worked loose it could cause something like this.
I could be way off but it seems like something upstream from the coils that's causing the issue. I'd check all the wiring for something loose or damaged.
I could be way off but it seems like something upstream from the coils that's causing the issue. I'd check all the wiring for something loose or damaged.
Last edited by Wookie; 02-13-2017 at 02:54 PM.
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If the plugs and coils are new changing them won't do anything other than thin your wallet. Have you checked the fuel rail pressure when it's under a load? If the filter is getting clogged it could cause something like this. Since the problem seems to be moving around I would suspect a fuel delivery problem more than an injector acting up. Changing the fuel filter and checking the rail pressure will let you know if there's a problem there. Injector cleaner won't hurt anything either.
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I want to say there should be around 40 psi at idle on that truck. Do you have a way to check the fuel trim levels or the O2 sensor values? If so check them and figure out if you're running lean under a load. Also, look up the specs for the fuel pressures. It's starting to sound like you have a fuel delivery issue.