Hey Fellas

New to the forum and liking what i see so i will post my question .
i got a 2002 F-250SD 5.4L. yesterday i was driving down the highway and it started losing power and running rough . i came home and plugged my obd2 tester on and it through the codes P0303 P0304 P0308 P0300 P0358,
All miss firing cylinders . just curious if any of you have encountered this problem . ive been told its the coil or catalytic convertor . If its the Cat im going to cut it out since there are no emissions laws in the Province of Alberta .
Input would be great thanks in advance

Cheers

 

I have never seen several coils all go at the same time. What you might want to check would be the connections to those misfiring coils 3,4,8. Sometimes water gets back there and does it's thing to cause problems. Also, remove and make sure the plugs at the PCM don't have any corrosion. Has any work been done recently at the back of the engine where those coil/injector plugs were moved around leaving some loose?

 

Possible causes

- Faulty spark plug (s)
- Faulty ignition coil (s)
- Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure


Since you have a P0300 code which means that a cylinder(s) is misfiring or is randomly misfiring, I would start by checking for intake leaks. How many miles on the spark plugs?

 

There 211xxxkm on the truck it's 131xxx miles , last we did a compression test and cylinder 8 and 4 have no compression in the cylinders. Could this be caused by a intake leak ?

 

I wouldn't think so.
There are 2 things you can try.
Remove the valve covers and look for broken valve springs on those 2 cyls.
Do a leakdown test to determine if there could be camshaft or valve problems.