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Alex, ASE Certified Technician
Category: Ford
Satisfied Customers: 1158
Experience:  ASE Certified Master Technician, L1 Advanced Level Specialist
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2004 Ford F-150: rough..stay running..misfire in cylinder 3 & 4

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I have a 2004 Ford F-150, 5.4 V8 that began running very rough and would not stay running at idle. Initial error odes indicated possible Crankshaft Position Sensor error, misfire in cylinder 3 & 4, Bank 1 running lean and Bank 2 running rich. Replaced Sensor, Cylinder 3 & 4 coil packs/spark plugs and removed Throttle body and cleaned. Vehicle does not die at idle but is still running rough. Have removed coil wires from cylinders 2-4 while vehicle is running and it does not appear to make a difference in the engine's performance. Remove wires from other cyclinders and engine performance declines. When I place my hand by the tail pipe the flow of exhaust seems to be blowing out and breathing back in. At a loss for what to do next.

Louie Villa
Maricopa, Az.
Hello. My name is XXXXX XXXXX I'll be assisting you with your question.

It sounds like you may have a bad injector on cylinder 3 or 4. One injector could be pulling voltage from the other and causing 2 cylinders to misfire. I would check resistance on the fuel injectors individually with an ohmmeter. The fuel injector that is open or has higher resistance than the others will be the bad injector.
Customer: replied 5 years ago.
Would this affect the injector's performance. I forgot to add that we removed the passenger side injector rail/injector and all of the injectors are spraying fuel.
They may all be spraying fuel but one could have high resistance and in turn pull amperage away from the other injector. This may cause the injectors to partially open and cause lean misfires. I feel that a resistance check on each of the injectors may give you a better idea of the problem. I would expect to see a higher resistance reading on injector 3 or 4 than the others.
Customer: replied 5 years ago.
Alex thank you for taking the time to help with my problem. I just checked with my nephew, who has been helping me with this problem, to verify what I have been describing. He has the list of the codes that were being passed. He said that Bank 1 (cyl. 1-4) is coding as being rich and Bank 2 (cyl. 5-8) is coding lean. Everything else is as I have described.

I aplologize for the mix-up and any confussion thia may have caused.
If bank one is running rich that changes my mind about the fuel injectors. I now suspect a problem with the VCT (Variable Camshaft Timing) solenoid. This is a common failure on these engines.

I suggest to first attempt to flush the VCT using the following procedure. If after flushing the VCT the condition is not improved, the VCT will most likely need to be replaced.

Start the engine and while holding the engine RPM at 1500-2000 RPM, hold the VT/LB wire to ground through the jumper wire for 1-2 second intervals. The engine RPM should react to the grounding and release of the jumper wire as it forces a change in camshaft timing. Repeat the grounding and release of this circuit 20-30 times to flush engine oil through the actuator and camshaft gear assembly. Then, recheck the engine idle quality.

Here is the VCT replacement procedure for reference:



  1. Disconnect the battery ground cable.



  1. Remove the parts in the order indicated in the illustrations and tables.

Item 3: Power Steering Support Bracket and Reservoir Assembly Removal Note

  1. Position the power steering support bracket and reservoir aside.


  1. To install, reverse the removal procedure.
Alex and 5 other Ford Specialists are ready to help you
I want to add that there is still a chance the fuel injectors could be stuck open on 3 and 4. It is definitely a good idea to check the resistance on those injectors to be sure.
Customer: replied 5 years ago.
Thanks Alex. I will try these solutions tomorrow morning.
You're welcome. Let me know what you find. Thanks!
Customer: replied 5 years ago.
Alex - What are the VT/LB wires (violet/light blue)? I cannot find them on the passenger side of the motor, which I am taking as Bank1.
Did you locate the VCT? The violet / light blue should be on the connector to the VCT. I'll take a look at the wiring diagram later and get back to you.
Ok here are the connector views. If the wire isn't violet/light blue it may be dark green/orange. In either case it will be on the 2-wire VCT connector:


Customer: replied 5 years ago.
Alex - Thanks for the help. This turned out to be a much more serious problem than we originally thought. After removing the VCT and seeing it intact my nephew and I took the truck into a friends shop. We removed the valve cover off the Bank 1 side and discovered a broken valve spring on the #3 cylinder. Luckily the valve guide did not drop down into the cyclinder and damage the piston. My nephew and his friend are removing the head today. Looks like I will be possibly replacing a Bank1 head.

Again, thanks for your help.

You're welcome. I'm sorry to hear about the valve spring. Thank you for getting back and letting me know what happened. Sorry I couldn't deliver the silver bullet on this one, but I'm glad you're getting it fixed.