89 F150 351W skip/misfire

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Feb 8, 2012 | 03:47 PM

emloera

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89 F150 351W skip/misfire

I recently bought a 1989 F150 with a 351W, C6, and 4x4. The truck fires up and idles like a new one. Sometimes it will try to stumble around once you put it into gear, but that is a rarity. The real problem comes in at highway speed. It will skip/misfire around 50-55mph if you try to hold speed. Under heavy acceleration it runs great with normal 351 power. I have felt the concern both when it's warm and cold, although I've noticed it more when it's warmed up. I thought a tune up would solve my problem, but to no avail. Here is a list of what I have done:

-motorcraft plugs gapped to 44
-ford racing 9mm wires
-motorcraft rotor
-new dist cap
-new fuel pressure regulator
-new 195 degree thermostat

This problem seems to be fairly common with these trucks... hopefully somebody can shed some light on it for me!

Feb 10, 2012 | 08:56 AM

rla2005

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From: Kentucky

Here is some light from Steve83: 1983 Ford Bronco TSBs & FSAs (Recalls) for '83-96 Broncos & F150s

Feb 10, 2012 | 01:26 PM

Bronkenstein

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From: Glen Burnie, MD

could the "crossfire" from the wires make it want to stall?

Feb 10, 2012 | 01:42 PM

Ole' gray

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From: Missouri

If two plugs fire at the same time, the pistons will want to counteract each other, and that sounds like it could be really hard on the motor.

Feb 10, 2012 | 01:48 PM

rla2005

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From: Kentucky

Quote:

Originally Posted by Bronkenstein

could the "crossfire" from the wires make it want to stall?

Not very likely.

Sep 11, 2018 | 04:06 PM

Nicholas Smith

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same could i get some help

Sep 11, 2018 | 04:26 PM

rla2005

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Joined: Oct 2005

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From: Kentucky

Quote:

Originally Posted by Nicholas Smith

same could i get some help

Starting your own new thread would be highly suggested. Cross posting in a thread that has already morphed into multiples only results in confusion.

Based on your video and statements: No Codes. You most likely have a bad computer. And I also would expect multiple issues given your other info about the truck's history.