My 5.4 suddenly started missing on 4 cylinders at once. Codes are P0351, P0352, P0353, & P0357

Coils were tested OK by dealer.
Crankshaft Position Sensor was replaced
PCM was reprogrammed by dealer
Nothing has fixed it yet.
These are the first 4 cylinders in the firing order

Anyone ever seen this or have any ideas for a fix

any help appreciated...

 

Could be a wiring problem, like something came unplugged? If the dealer can't fix it, it must be bad!!
Jimmy

 

Dealers are just like anything else....some are good some are ***
Most likely wiring or fuel system wiring or computer.

All of those things that were done by the dealer should not have been touched. when you have an issue with multiples its much easier to diagnois. First there is a plug in light that you plug into to test to see if the injectors are firing. Also there is some kinda testor to test the signsl going to the coils. One of those two should reveal the problem...???? gonna look at my book.

 

Looks like the pcm maybe bad. I'd sure like to work on that one..

Dick

 

cylinders are 1, 2, 3, & 7 with are the first four in firing order 1, 7, 3, 2.

Dealer thinks its a wiring short or problem but wants several hundred dollars to hunt for it. I think a good wiring diagram should show where this 4 are close together or something common to them. I don't have one and I'm not sure I want to spend the $160 for a shop manual when I'm not sure if it would have the detailed wiring diagrams I would need. I fear it is a problem in the wiring harness where it goes through the firewall to the PCM.

 

I replaced the Crankshaft position sensor before I took it to the dealer. It was an inexpensive part and guess work.

I think the dealer checked the injectors. Not sure. The OBD codes says malfuctioning primary or secondary coil. Dealer says the coils are not firing or getting trigger signal, they just do not know why. I'm trying to locate a Ford wiring diagram for it to see if the leads are close together where they go through the firewall to the PCM.

1997 Ford F250 XLT Supercab with 5.4

 

I looked at my 99 wiring diag for my 5.4 and it looks like the computer.. for my year nothing is common except the 12v check for 12v to the coils and the injectors with a test light to ground key on. there is a union not a connector as far as I can tell. They call it a splice...Thats on a 99 though. I'll see it I can hunt down a diag

Dick