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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 48337
Experience:  16 years experience
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f150: 5.4l..misfiring and shuttering..around 50 mph it lowers rpms

Resolved Question:

i have a 04 f150 5.4l it has been misfiring and shuttering when at around 50 mph it lowers rpms and will not accelerate unless i release the accelerator then reapply pressure
Submitted: 5 years ago.
Category: Ford
Expert:  Chris (aka- Moose) replied 5 years ago.

Hello, I'm Chris.
I will do my best to answer your question fast and accurate using the info you have provided. Thanks for visiting Just Answer.


At this time is the scan tool power balance test picking up any misfires or cylinder not contributing equally?


Are there any trouble codes stored?


Customer: replied 5 years ago.
not at this time and there are no codes stored. when we ran a operation scan the rpms wer fluctuating but nothing else seemd wrong
Expert:  Chris (aka- Moose) replied 5 years ago.

So when you ran those test it still was misfiring but there was no computer/scan tool proof of it?


Did anyone monitor TCC or TCCSLIP or compare TSS to RPM?


Customer: replied 5 years ago.
Correct It is weird it will misfire then stop then start again and no we did not compare those or check those and I don't even know what those abbreviations are
Expert:  Chris (aka- Moose) replied 5 years ago.

This misfire does it feel like the vehicle has random hiccups or is it just a short set of vibrations lasting under 3 seconds?


Customer: replied 5 years ago.
Random hiccups
Expert:  Chris (aka- Moose) replied 5 years ago.
Your going to need to get into more diag to check for dropping out injectors or variable cam timing issue. You are going to need to use a oscilloscope to diagnose this to see if the signals are always consistent and not dropping out causing a lack of ground pulse to the injectors or coils. Or if there are input issues to the PCM like the cam and crank sensors.
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