under load miss

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Oct 4, 2015 | 05:06 PM

samthelion

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From: W Cen. FL

under load miss

2000 Explorer Sport 4.0. I just did the heads, valves, decked, proofed. New wires, plugs. Followed the procedure to the letter. First two starts were a bit touchy, but now starts fine and purrs like a kitten at idle. The problem; under load it acts like it drops a cylinder. Any ideas? Bad plug, bad wire, fouled injector? This thing is driving me nuts. Thanks.

Oct 4, 2015 | 06:35 PM

shorod

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From: Cedar Rapids, IA

Have you checked for pending misfire diagnostic codes?

-Rod

Oct 4, 2015 | 08:01 PM

samthelion

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From: W Cen. FL

Oh, my.

Not yet. Thanks for the tip.

Oct 5, 2015 | 05:50 PM

samthelion

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From: W Cen. FL

UPDATE

Talked to my mechanic friend today. He recommended that I scan it for coil pack break down. After fifteen years that is most likely it.

Last edited by samthelion; Oct 5, 2015 at 05:51 PM. Reason: spelin

Oct 5, 2015 | 07:16 PM

shorod

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From: Cedar Rapids, IA

And a misfire diagnostic code would point that direction, but if the misfire codes only point to one cylinder, then it may not be a coil issue. Some scan tools can even access the PIDS for Cylinder Misfire Counts so you can see how many misfires are measured by an individual cylinder which can identify a cylinder that is misfiring long before it triggers a diagnostic code.

-Rod