I just picked up a 2004 f350 4x4 with a 5.4 in it. It has approx 120k on it. Driving home I noticed it kind of shuddered at low rpm, put the scanner on it at got misfire on 7. Could a misfire only show up at low rpm?

What year did the f350 go from a 2v to a 3v? Did the 2v have the same problem with breaking plugs?

One more question, Im going to change the COP and spark plug on cylinder 7 to try to clear up the shudder. If i found a parts truck, what years cop would be compatible?

Thanks

 

Yes my misfires only showed up when trying to accelerate in OD under 1500 rpms...more stress on them i guess. 3v starts in 2005. No 2v spit them out but you really don't have to worry about that with an 03 or 04 because they have longer threads as long as they are torqued properly. 99-04 are compatible i believe but i would just buy a new spark plug...they are cheap.

 

Also don't be afraid of accel coils. A lot of people talk crap on them but i replaced all 8 of mine about 100,000 miles ago and they have been flawless and only $200 for all 8.

 

Definitly not going to put used plugs in. Was just wanting to swap a used coil on to try it. Ford dealership wants 120 per coil up here in Canada.

 

If you just want to verify the coil failure, you can switch it with one of the others and see if the misfire follows the coil location.

Have the plugs ever been changed? If not, then you should replace ALL of the plugs (If the 120K is miles). It could very well be a plug failure and the coil may be OK, but if it has been driven for very long with a bad plug, the extra stress that puts on the coil frequently causes the coil to fail also.

Plugs should be replaced according to your maintenance schedule (usually at 100K miles). Coils should only be replaced when they fail.

A coil from any Ford 5.4 or 6.8 engine should work OK.

 

Thanks for the help guys. I wasn't sure if coils should be replaced as part of routine maintenance or not. I plan on replacing all plugs, I just want to put as little money into truck until I solve the misfire issue.

 

I would change the COP boots and spark plugs first. If the misfire persists then replace the coil. The boots can deteriorate over time and once the spark plugs have 50k miles on them they can be on borrowed times.(despite Ford's 100k change interval) I keep a spare coil on hand for my truck but in reality a lot of good COPs get replaced when the problem is elsewhere.

 

Swap the #7 COP with #5 and the #7 spark plug with #3 (or what ever is easiest for you)

Rerun test.

The misfire should follow the bad part.

 

When testing things out, if you swap the COP to another cylinder then there is no need to swap the plug to a different cylinder as well. If the plug is faulty, the code will remain the same. If the COP is faulty, you will get a code for the cylinder the COP is on.

 

I swapped the coil from 7 to 5. The engine was really dirty, doing my best to clean everything up as i go. It seemed to run a little better but still getting a little shudder at low rpm at higher speeds. I did not get a new code (only have a bluetooth scanner hooked up to my phone with the torque app) Does that rule out a misfire as cause? or could I have a misfire and no code show up right away? Only drove it for 10 min. Getting new spark plugs in the next couple days, just havent had time to make it to Ford.

 

Yes, you should move the spark plug also. If you move all of the parts but the miss still stays at the original cylinder, you've eliminated the ignition components as being the cause and move on to mechanical or fuel delivery issues.

 

NO. The check engine light is NOT an engine monitor. It IS an emissions monitor. It will only set the misfire code when the misfire exceeds the programmed emissions standards. This typically takes many misfires and several drive cycles.

 

don't forget to use Di-electric grease on the boot. It keeps them from sticking to the plug. I would just change all the plugs and just swap one coil for another also check the wires to the coils and mack sure they are in good shape.

 

As suggested, check the boot. My uncle has a 3v v10 that had a faulty spring in the boot. Took a while to find.

 

So misfire followed the moved coil. It took a couple trips but it threw a code. Im going to order 2 Coils (1 spare if another fails) 8 plugs and im thinking of replacing the boots on the rest of the coils. Is that a good idea? What brand boots are best? I want to order from rockauto because they have great prices on motorcraft coils, but i dont see motorcraft boots on their site. Thanks for all the help guys, I would be lost without these forums.