Uncleford

Hey guys, I have a 2001 f150 5.4 4x4. The other day it slowly started running rough so I waited for the cel light to come on and read the code. I figured it was a coil pack before I saw po-357. (truck has 138k) So, I bought the coil pack at autozone and replaced it. After replacing number 7 cylinder and starting it, I had the same problem as before.

This tIme I read the code again and it was the same po-357 so I figured it was the spark plug. Today I bought new plugs and just changed out number 7 cylinder. (I didn't want to change to many things at once - and plan to replace all when problem is figured out). I start it up and damnifi don't have the same problem. Cel comes on after a minute or two and still running rough.

I need some help. What else can I check? I find it hard to believe that I got both a bad coil pack and a plug. Anyone have any thoughts on this?

Thanks!

biglee88

You should switch the fuel injectors around like 5 and seven see if it moves with the injectors

Uncleford

I thought about that but wouldn't it throw a different code than po-357. I'm willing to try but what a pia #7 is to get to. I'm pulling the fuel rail each time...ok, off to pull it apart again...any other suggestions?

udderbrudder

How about switching coil & plug with another cylinder. That would at least eliminate the poss. you got a bad part. Also verify for signal to the coil. You can use a "noid" light for this. It'll flash if coil is getting signal.

Uncleford

Ok, now I'm really confused...this morning I changed all the plugs, even replaced the new one that I replaced two days ago. I pulled 5,6, and number 7 injectors ( thinking maybe some trash got on them when I pulled the fuel rail) and cleaned all of them. I swapped number 7 coil pack with number 5 coil pack. When I start it up...same problem. I had the same miss.

I don't have a scanner and the nearest parts place is about 20 miles so I start pulling injector plugs and coil pack harnesses. All cylinders had a change EXCEPT number 7. Grrrrrrrr!

I couldn't find my noid light so all I could do was pull the harnesses ( on inj and cp) to verify they all had power. All of them did..

What am I missing? I had triple checked everything I can think of. Is this maybe a harness problem? A bad computer? I'm outta ideas...

When the truck started acting up it was normal...meaning just like every other 5.4 that I have owned for the last 10 years. It started with an intermittent stumble then later it got worse and finally the cel came on and I read the code of po-357...I dunno...someone fix me...thanks for the help guys

cgouldy

I have a 4.6 and I have had the same trouble I Changed all plugs and all 8 coils. I still get a Miss on Coil One I get the same code P351 which says the same thing just tells me what coil. I have replaced the coil first time with Napa coil. So the other day I replaced it with Ford motocraft coil cause ford machanic said that was my problem cause I wasn' using ford coils. Only one giving me problems is coil 1. So I replaced it only with the motocraft coil. When Its hot outside above 90 degrees and my AC is running it begins to missfire on coil one. I wish I could find out what the problem. I have had the computer scanned by Ford and they say its not the computer. I"m out of Ideas to. IF you figure it out please post what you do so mabe I have the same problem.

Chris

TRD-Toy

I would check that the coil is getting triggered (grounded). Use a noid light while running. If it doesn't flash the noid light then trace the wire back to the PCM. If the wire checks ok then you'd either have poor pin fit at the coil connector or a bad driver in the PCM.

biglee88

If it was me I'd noir light both run compression on the cylinder and go from there

Uncleford

Ok, not much to update but here goes. Using a test light I was able to check that the coil is indeed firing on #7 though my code reads PO-357. I then went and checked the injector on # 7. It was not firing the light. So far this is as far as I have gotten.

It looks like it will either be a broke wire in the harness going back to the PCM or a bad driver in the PCM as mentioned earlier.

If it is the PCM..what will I have to do? Replace the computer and then have it reflashed at Ford? What does a PCM and a reflash cost? I take it that in my worse case scenario that I would have to drive it there first and change the computer in the parking lot then push it inside for them to reflash so my PATS will work and start?....Thanks...

udderbrudder

So now you need to determine if inj. 7 is missing power or gnd pulses at the connector. If it's power missing, you can "borrow" power from another injecto or even right from the battery (temporarily) to verify the inj works. If you have power at the connector but no gnd pulses you may have to trace back to PCM to determine if your getting pulses out of it. If yes, then run a new wire to the injector and splice it in.