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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 36084
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I have a customers 2001 Ford f150 4.2 6 cylinder. Truck died

Customer Question

I have a customers 2001 Ford f150 4.2 6 cylinder. Truck died and would not start. Typical harmonic balancer came apart and ground down the crank position sensor. Replaced both and truck started right up and ran beautifully. Upon driving it home the customer reported the check engine light came on. It was a P0302 and P0306. While the vehicle was not misfiring, seeing that these were the center two posts of the coil I replaced that figuring it may be breaking down under heat. Same two codes came back. For the hell of it I replaced the crank sensor just in case and they still come back. Plugs, wires, injectors, everything fine. Ever hear of this?
Submitted: 1 year ago.
Category: Ford
Expert:  Ron replied 1 year ago.

Hello and thank you for your question,
One very common caused for these to fault codes to set can be caused by EGR passages in the intake manifold becoming restricted. In order to determine if in fact that is the case you will need to remove the upper intake manifold to expose the runners of the lower intake and clean the carbon from all passages . Its very common for them to restrict on the 4.2 as well and I would suspect thats what you dealing with here. If the engine is actually missing you can also disconnect the vacuum line from the EGR valve and see misfire clears. If so then the passages are restricted.

Expert:  Ron replied 1 year ago.

If you end up having to remove the upper plenum to clean the passages it would also be a good idea to install the updated o-ring gaskets between the upper plenum and the lower intake manifold, along with the updated isolator bolts that hold the upper plenum to the lower intake manifold. There are know issues with the old style gasket and isolator bolt leaking .