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Pete
Pete, Auto Service Technician
Category: Ford
Satisfied Customers: 24697
Experience:  Over 17 years diagnosing and repairing automobiles various makes and models with some training and certifications.
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I have a 2008 f150 4.2L running rough. I have changed

Customer Question

I have a 2008 f150 4.2L running rough. I have changed ignition, plugs and pcm as it appears that I have no spark no #3 or #4 cylinder. checked wiring can not find any broken wires. don't know what else it can be
Submitted: 1 year ago.
Category: Ford
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to help with this today.I apologize for any delay.I need a little more info to assist better on this here.

Was the ignition coil assembly replaced to try and correct this issue here at all?

Were the spark plug wires replaced at all for this issue to try and correct this issue?

Let me know so we can continue,thanks Pete.

Customer: replied 1 year ago.
replaced ignition coil and plug wires
Expert:  Pete replied 1 year ago.

Is it only cylinders 3 and 4 that have no spark?

Customer: replied 1 year ago.
only 3 & 4 dead at tower on ignition coil
Expert:  Pete replied 1 year ago.

I apologize for the delay.

If you wiggle the wiring harness leading to these coils or at the coils does spark come back at all even briefly?

Let me know,thanks Pete.

Customer: replied 1 year ago.
pulled harness absolutely nothing happens
Customer: replied 1 year ago.
is it possible for radio interference capacitor to effect signal?
Expert:  Pete replied 1 year ago.

If there is a short with the capacitor this may be causing a fault like this here so this is possible.With all that has been checked and done already to try and locate and resolve this here if there is an issue with this capacitor I would replace it if you can and see if this resolves the fault here.

Thanks Pete