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I have a 2010 F150 with a 5.4 3V missing on cylinder 8 and…

Customer Question
I have a 2010...

I have a 2010 F150 with a 5.4 3V missing on cylinder 8 and 4. I have swapped the plugs,coils and injectors with no luck. coil is sparking and checked injector with noid light and it all checks out.

Mechanic's Assistant: Just to clarify, what are the exact lights you're talking about?

Cylinders are misfiring

Mechanic's Assistant: Are you fixing your F150 yourself? What have you tried so far?

spark plug and coil

Submitted: 3 months ago.Category: Ford
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Answered in 3 minutes by:
3/16/2018
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago
A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6,926
Experience: ASE Master Certified, ASE Advanced Gasoline Engine Performance
Verified

It may be a mechanical problem internally in the engine. I would recommend doing a manual compression test on engine. The cylinders should be around 175 psi each. We have seen issues with the camshaft followers (rocker arms) coming out and not opening the valves. Your engine has 2 intake valves and 1 exhaust valve per cylinder. If one of the followers falls off one of the intake valves, you can get a miss fire on that cylinder.

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Customer reply replied 3 months ago
I have done a compression check on both cylinders and 180 on both
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

Then remove the valve covers and inspect the camshaft followers. Make sure they are all intact. You have eliminated the coils, spark plugs, injectors and wiring.

By the way, what are the trouble codes you got for the miss fires?
Example P0401

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Customer reply replied 3 months ago
I have pulled both valve covers and everything seems to be in order. all valves are moving up and down. cams look good
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

How did you narrow down to cylinders #8 and #4?

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Customer reply replied 3 months ago
scan tool. snap on
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

What were the trouble codes you got with it?
Example P0401

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Customer reply replied 3 months ago
can not remember the exact code # but it was misfire cylinder 4 and 8.
The contribution test on the scan tool is a steady miss on both cylinders
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

Ok. Because if it is P0304 and P0308, it is not the PCM (Engine Computer). But if they were P0354 and P0358, then it is internal in the PCM.

A miss fire is caused by---

Wiring

Coils

Spark plugs

Injectors

Internal engine (valve, piston rings, camshafts and followers)

You have eliminated all of those items with what you have told me.

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Customer reply replied 3 months ago
p0304 and p0308 are the codes
and I even tried a ecm.
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

And no matter what repairs you do, those same two codes return?

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Customer reply replied 3 months ago
sir
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

Does it miss fire constantly or intermittently?

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Customer reply replied 3 months ago
constantly and tried intake gasket just in case of vacuum leak
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

Lets make sure you are working on the correct cylinders.

1-2-3-4 are on the passenger side starting at the radiator and 5-6-7-8 on the drivers side starting at the radiator.

So #4 and #8 are the last cylinder on each side.

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Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

And you swapped the injectors with a know god cylinder and also the coils and plugs?

You have a bright blue/white spark at the coil?

And you have a good power and pulsed ground to the injectors?

Compression test is 180 PSI.

And you inspected the valve train and it is all intact and the followers are in place and no scoring on the camshaft lobes where they contact the followers?

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Customer reply replied 3 months ago
that is correct I check all of those. I am at a loss
Ford Mechanic: A. Penland, Ford Senior Master Technician, ASE replied 3 months ago

Everything you have told me tells me the engine is not miss firing and running fine.

All an engine needs is fuel, air and compression.

There is nothing else that can cause the misfire you have.

There is not much more to look at.

Only thing else is to wiggle the injector and engine harness while the engine is running and see if you can get it to change.

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