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Jan 30, 2011 | 08:46 PM

murmac

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misfire,

Hey I am new to this, I have a 2005 f150 4x4 with a 5.4 it was studdering on the highway under light load, i changed the plugs and coils it worked great for a day now working worse and giving a misfire #7, so i swapped the injectors around still misfire #7. any ideas????

Jan 30, 2011 | 08:51 PM

1bad67sbf

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From: northern va

pull that plug again and make shure it did not crack when installing and when you put it back together swap that new coil with another one some where else.

Jan 31, 2011 | 03:51 AM

svt2205

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From: Sunapee NH

Before pulling the plug, verify that your connector on cylinder #7 is properly seated. I've had trouble with the connectors not completely seating.

Could be the plug or COP is bad. But it could also be too much anti-seize was applied.

Hope it's an easy fix.

Jan 31, 2011 | 07:24 PM

murmac

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I swapped plug and coil from another cyl and still misfire #7, is there any fuel pressure or compression issues?

Jan 31, 2011 | 10:41 PM

Wilber15

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From: Duluth, MN

Usually fuel pressure issues will show up on bank 1, being as it's the last side to get pressure. Disconnect both the injector harness and the cop harness, and connect a noid light to the harnesses and make sure it flashes with the engine running. A test light can be used for this, but keep run time as short as possible. If you the light pulses on both circuits, it's possible you have a bad injector or compression problem.

Feb 1, 2011 | 07:42 PM

murmac

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tested coil and injector with <led> test light all good, what should i have for compression? didn't have a misfire #7 until i changed the plugs, but i swapped plugs from cyl to cyl and coils --still #7 misfire