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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6603
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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I have a 2008 ford F150 5.4L and I have had an ongoing

Customer Question

Hello,I have a 2008 ford F150 5.4L and I have had an ongoing problem with an engine misfire on cylinder 1 and on occasion cylinder 3. I have replaced the coil packs, spark plugs, mass air sensor, throttle body, VCT solenoids and I still have the same issue. This happens only when the engine is cold and when warm the misfire goes away with only an occasional misfire.
Submitted: 4 months ago.
Category: Ford
Expert:  A. Penland replied 4 months ago.

Are there any ticking noises from the top of the engine from around either valve cover area when the engine is running?

Customer: replied 4 months ago.
nothing that sounds out of the ordinary, there is a slight ticking sound that the engine is making but it does not appear to be localized to the valve cover area.
Expert:  A. Penland replied 4 months ago.

These engines are known for rocker arms, now called followers because the push rods are no longer used. Your engine has 2 intake valves per cylinder. And is one follow is failing, one valve will not open properly and cause a miss fire as you describe. Also, the lifters, now called tappets, are prone to collapsing and cause the valves to not open fully which will also cause a miss fire. You will have to remove the valve covers to inspect them.'

Customer: replied 4 months ago.
With this issue will this only happen when the engine is cold? Are there any other symptoms that I should look for with this issue?
Expert:  A. Penland replied 4 months ago.

Also, valves sticking in the valve guides. Basically items limited to a specific cylinder, not all of them. Since you are only getting miss fires on cylinder 1 and cylinder 3.

Customer: replied 4 months ago.
when the truck warms up this goes away. When the truck warms up it runs very well and gas mileage has not been affected. When it's cold it will run rough and if I give it gas the engine will surge up and down and after a few seconds it will level off and run normally. I will then get a check engine light with a P0 303 or P0 301 or on a rare occasion P0 300 code but 95% the time it's P0 301
Expert:  A. Penland replied 4 months ago.

Have you done anything with the fuel injectors?

Customer: replied 4 months ago.
just replaced #1 but did not change anything, still getting P0301 and truck runs the same
Expert:  A. Penland replied 4 months ago.

Then, the problem is mechanical. You have replaced the coil, injector and spark plug.

Customer: replied 4 months ago.
the coil, plugs, injector on #1. So when you say mechanical this would just be valves and or related systems or can it be the cam or piston
Customer: replied 4 months ago.
or can it be an air leak on the intake manifold or throdle body?
Customer: replied 4 months ago.
Thanks for your assistance, the above were my final questions.
Expert:  A. Penland replied 4 months ago.

I would look at the valve train under the valve cover on the passenger side. Check the cam lobes for scoring from a failing follower. Also, when the engine is cold, check the followers for looseness compared to the other ones.

It could be, but they usually take a while for the leak to seal once the engine warms up. Like the intake gaskets. But you would have to drive it for about 20 minutes for it to seal.

Customer: replied 4 months ago.
Thank you for your insight, have a great night
Expert:  A. Penland replied 4 months ago.

Your very welcome. Thank you.