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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 34813
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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F150 runs rough

Customer Question

f150 runs rough
Submitted: 1 year ago.
Category: Ford
Expert:  Ron replied 1 year ago.
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
In order to be able to try and help you you are going to need to add more information, I need to know what year your F 150 is as well as engine size and any repairs you have made to correct this concern. Post back with complete information and we can work from there.
Customer: replied 1 year ago.
New Engine, 2007 5.4 v, Miss fire #1,#7,#8 cyls. Injector replaced #1 & 8, also coils. Noid light shows injector firing also pulled fuel rail to verify fuel delivery. Coil firing plug, compression approx. 175lbs. Still runs rough lack of power. Sprayed intake to look for vac. leak no difference. Cyl. contribution on scanner shows constant miss on cyls., very light throttle count goes to 0 on all cylinders but 7. Truck sat for approx. one year with motor out so I checked ground connections etc. Changed & flasher computer same results, wondering if old fuel might be a issue, had a corrupt flash program years ago on a ford 4.2, possible rebuilder might have timing off a tooth?? have not checked. Pull cam sensors no difference on miss count, maybe limp mode?? Looking for possible fix.
Expert:  Ron replied 1 year ago.

Old fuel could cause all sorts of problem, if you are sure you have good spark, compression and injector pulse. I would start with getting some fresh fuel in the tank and clear all codes and see if the misfire clears. I would also make sure you do not have any back pressure in the exhaust system. Check these for me and post back and we can work from there.

Customer: replied 1 year ago.
fresh fuel no help, still same misfire.
Expert:  Ron replied 1 year ago.

Well as you know, you need proper fuel pressure, injector pulse, compression and good spark in order for the engine to run correctly . If you are sure you have all of these then did you check the exhaust for any restrictions?

Customer: replied 1 year ago.
Dropped exhaust, truck ran poor, seems very rich, able to keep just above idle, bank 2 counts constant misfires leading to believe timing may be a issue, rebuilder mentioned something about lifter problems they have had, no noise but might hold valve open?? Waiting to talk to their techs later. Thinking mechanical at this time, next will probably be pulling valve covers.
Expert:  Ron replied 1 year ago.

I would have to agree with everything else you have checked, there really is not much else left it could be. That is about the only thing left that makes sense.