I have had a miss in my 5.4 engine for about six weeks now. I found a thread dating back to 2011 about the problem, but even with 187 posts, no one had any true answer for the problem. I still don't have one either. I am getting about 8 miles to the gallon, and I am growing concerned about doing potential damage to the transmission, drivetrain, catalytic converters, or even the engine.
I am wondering as to whether anyone has ever figured out what the actual cause of the problem is, and how to repair it.I would appreciate any feedback, (preferably a solution), about this particular problem. The continuing vibration, cost of fuel, loss of power, and inability to solve this continuous miss, is just infuriating!
The truck is a 1998 F150, 5.4L 2V, 4x4 with a E4OD transmission. Just turned over 200,000 miles. I have done a coil swap, a plug swap, an injector swap, changed the air and gas filters, changed the PCV and it's elbow, and spent $29.00 on a TPS that it didn't need. Also removed and cleaned the MAF, the throttle body, and the EGR valve. None of it made a Damned bit of difference. Every time I put my scanner on it, I get P0301 misfire. No other cylinder. It is especially bad under the slightest acceleration. If I am cruising, or going down an incline, it is fine. Overdrive is strictly off limits. If I shift manually, it clears up over 3,000 rpm until I shift, and the rpm drops. If I use cruise control, it comes and goes as the road rises and falls. It has Motorcraft spark plugs with only 25,000 miles. I replaced the coils at 150,000 with units from Jegs. They all check out with a multi-meter, No cracks in the boots, no cracks in the coils. Fuel pressure is good, so is the pressure regulator. So.....WTF?

 

You better quit driving it until it is fixed. What codes does it have? Please post exactly what year the vehilce is, how many miles are on , and what has been done to it in the past and anything else that may be relevant. Many things can cause a miss, plugs, cops, fuel issue, valve issue, valve followers, valve timing issue among many other things. You have to get someone to check the codes and start troubleshooting.

 

What YEAR? 2 valve or 3 valve? Have you tried doing anything yet? Any codes? How many miles on the spark plugs and coils?

 

Dear Baffled,
Hook up a scanner to your truck and you should get a code for which or what cylinders are missing. If you don't have one, you can go to an Autozone or O'Reilly's and they will check the code for you. Usually, the problem will be ignition or fuel related. If its ignition related, it could be you live in a rainy area and some water made it down past the spark plug boot causing the misfire. It could be a loose connection on coil on plug coil, a fouled plug or a faulty coil. When you isolate which cylinder it is, and there's nothing visible to the eye such as moisture down the spark plug hole, a loose wire from the harness to the coil on plug or faulty spark plug, you can swap the coil to another cylinder and see if the other cylinder stops working to isolate the coil.
If its not the ignition, check the fuel system as far as a bad injector. You can either go to an Auto parts store and buy an inexpensive stethoscope and as the truck is running put the pointer on the stethoscope on each injector, one at a time. If you don't hear one clicking, you might have a loose connection on the injector or a bad injector. Another thing to check is the wiring going to either the coils or the injectors. Sometimes rodents chew on them. Good luck!

 

1. Get Forscan: https://forscan.org/home.html

2. Get this cable:
3. Go to Ford Tech Makuloco's youtube page and watch how he uses it. https://www.youtube.com/user/FordTechMakuloco

4. Solve your problem!

I hope this does it for you.

Its is an amazing tool and beats "Guessing"

Good Luck,

-Marko-

 

Time for a compression test.

 

What brand are the coils? You can't load test a coil with a multimeter.

Pull the plugs, read them, and do a compression test.