5.4 highway patrol f150

Old 04-25-2019, 01:09 AM
Thread Starter
Join Date: Jul 2012
Location: TUCSON, AZ
Posts: 49
5.4 highway patrol f150

Hey everybody. I just bought a 2010 f150 at an action in Phx AZ, Its a former highway patrol truck. I bought the truck as is. All the description said was, Its runs and drives, and was in fair conditions. The interior of the truck looked hardly used at 150,000 miles. $5000. So I bought it. I noticed it had what I thought, seemed to be a u joint, jerking, and ticking problem in the engine. Drove it from Phx to Tucson. and it started rough stumbling and knocking sound, after the 90 mile trip. Engine light came on with a PO306 code(misfire #6). went to start it the next morning and the knocking noise was more severe( like hitting a plastic can with a stick sound). Sound seems to be from the upper part of the engine.
I was wondering if anyone can point me in the right direction as to where to start looking. I have absolutely no knowledge with the 5.4 3v engine. I pulled the plug from #6 and it was charred up pretty good.

Old 04-25-2019, 07:15 AM
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Join Date: Jan 2007
Location: Vernon, NY
Posts: 8,742
If it's only one cylinder, then first suspect would either be leaking injector or faulty coil. The easiest is replacing the coil and trying that.

Though, at 150k, I would replace all of the plugs and coils. Use only Motorcraft.

In fact, since it was probably classified as "heavy service", I would recommend doing a full tune up on it. Including flushing the coolant.

If you search, you'll find a bunch of good information about the 5.4l 3v.

As for parts, I recommend Rockauto or Tasca.

Good luck.
Old 04-25-2019, 10:52 AM
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Join Date: Dec 2006
Location: Joplin MO
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Phaser knock. You are probably in for a new timing set and high volume oil pump.
Old 04-25-2019, 11:37 AM
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Location: So. Texas
Posts: 2,040
As stated, a possible phaser knock but that usually sounds more like a diesel engine knock. I'd also be looking for a cam follower gone bad. Pulling a valve cover can pretty much tell you about that. Might try to localize the sound using the stick method. Get a stick of about 3 feet in length and place it on different parts of the engine. Put your hand over the other end and put your ear on your hand. It's a poorboy stethoscope. I'd start at cylinder #6. If the exhaust cam follower is bad, the engine will keep cramming fuel into a cylinder that that exhaust side isn't working right and will foul the the plug.

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