Ford F150 knocks and misfires bad all of the sudden

Asked by Sep 06, 2015 at 10:32 PM about the 2000 Ford F-150 XL Extended Cab SB

Question type: Maintenance & Repair

The day before the truck ran fine.The next morning It was knocking and running on what sounded like 3 or 4 cylinders.I took it to the local Ford dealer and paid 70 bucks to have it hooked to their diagnostic machine. They said it had jumped time on the chain.I had them replace the timing chain and gears,gave them 2,500 bucks and towed my truck home because it wouldn't run after they "fixed"it.I pulled the heads and took them to a reputable shop and they were perfect,proving the fact that it hadn't jumped time (no bent valves etc.).I put the engine back together and got it to run like it was when I took it to the dealer to be fixed but no better.I then pulled the engine and replaced it with a 4.6 from a very rusty 1998 F150.It ran fine in the donor truck but once installed in my truck it ran exactly like the engine I took out.I have since dropped the fuel tank,drained it,replaced with new gas,changed the fuel filter,changed the fuel pressure regulator,changed the mass airflow censor,changed the throttle body,tried the ECM from the donor truck,changed injectors,etc,etc.
I have thrown thousands of dollars at this truck and I am at my wits end.What am I missing?

10 Answers


I'd file a complaint with Ford Customer Service at 1-(800)-392-3673 and try to get my money back. Then I'd trade the truck in or scrap it, cut my losses, and move on. In my opinion it's not worth fighting with. It's 16 years old. You can get something newer for your hard earned money. At this point you're just throwing good money after bad. HTH. -Jim

1 people found this helpful.

If you replaced your engine from another from another vehicle and you know that engine was running good the problem is in the exhaust system the catalytic converter or exhaust manifold is clogged. Start vehicle and let it idle for about 15 to 20 minutes and check manifold and converter if either one starts to glow red it is clogged.


also did you use any thing off the other motor like coils ignition system, wiring harness etc


and why pay or ask you to pay if hey couldn't fix it

I dropped the exhaust off of it today and let it run off the manifolds but it made no difference.I then unhooked the negative wire from the battery and ran a jumper wire from the positive side of the battery (while leaving the positive wire hooked to the battery)and let it sit for 10 minutes to clear the ECU.I then turned the key to the on position and waited 10 seconds and started the truck.It made no difference. I am using the wire harness that came with the donor engine.I just left it hooked to everything on the engine and plugged it in to the harness of the truck.As for why I had to pay for it,I had a loan on it and still owed 3 years on it and I had to pay for the "repairs"to get it back.And as far as cutting my losses on an old truck it has gone beyond that.This is now a quest for me,an obsession and I can't stop until I find the answer.I appreciate all the help I can get and I thank you all.


Is the knock coming from the top or bottom of engine ? Do this test start engine and get as close as you can to the oil pan if knock is noticeable louder the rod bearing need to be replaced. You can replace rod bearings with out removing engine just have to remove oil pan.

2 people found this helpful.

The knock I have is a spark knock caused by the timing being off which is causing a misfire condition.It is basically as if you turned the distributor of an older engine counter clockwise until the engine begins to sputter and knock and misfire but not far enough back to the point of backfiring.That's where my engine is at.The knocking is in the top of the engine by the way.Thanks for the suggestion is appreciated!


if the motor is running the same as the other one and you did not keep any of the coils then i would look at what you did not change ie maf, map,computer,vacuum lines that are on the fire wall . fuel pressure ground cables.

I will look into the ground cables as I have already changed all the other items you suggested. I also purchased a code scanner and I am hoping that it will give me some fault codes to follow up on too.Thanks for the advise.


I did the same thing once and found the fuel two fuel injectors to be faulty. With the truck running pull the plug wires one at a time from the coil pack. Check to see which one/ ones doesn't cause the engine to change. There would be at least one that will not create a change. -This may be the fuel injector you need to check. Pull the upper intake and remove fuel rail. -Check for any visual signs of it being clogged. With the fuel injectors out of the intake have someone crank the engine, they should all spray in series.

1 people found this helpful.

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