Hello Everyone,

I really need some help. I have a 2005 F150 5.4 with 140,000 miles on it. It has been a great truck so far and I really haven't had a serious problem, up until now. For the past few months my truck has had a miss when the transmissions shifts into overdrive and I am at a low RPM. I changed the plugs at 70,000 miles because it had started developing a miss at high rpms at the time. I figured that the plugs were getting aged again and this most likely was the culprit. After changing the plugs last night, I got in the truck this morning and realized the low rpm miss was still there in overdrive, then all of a sudden at red lights I noticed it missing at idle. Now the truck is considerably worse and is missing a ton at all rpms, but especially low rpms. No check engine light has come on. Any ideas? I used motorcraft sp515 plugs by the way. Still original injectors and coil's. I changed the fuel filter about 2 years ago.

 

did you check your air filter and cataliser????

 

Have you checked the coils?

 

No clue what a cataliser is, but... while Air Filter shouldn't cause a miss, not a bad idea to take a peek to make sure it is in good shape...

I would clean the MAF, they tend to get gunked up and cause a miss, and I am not sure how to check them, but with your mileage I would suspect the COPS have just about had it...

Are you getting any codes?

 

I will try cleaning the mass air sensor tonight. I haven't checked the codes, but no check engine light came on.

I changed the air filter not long ago and I also have no idea what a cataliser is...

I might go ahead and change the coils, since they have so much mileage anyway. what are the best brands to replace them with? is this an item I should only buy motorcraft on?

 

I'd only put Motorcraft coils on it


05 were also possible of having leaking injectors that can cause catastrophic damage to the engine.



First step will be reading the DTC(s) that set the check engine light

 

only motorcraft injectors only also? are parthouse injectors ok?

 

Do tell about the leaking injectors. I must have missed the memo on that...

I don't have any particular expertise on the COPs, but I have heard repeatedly that you should stay with Motorcraft COPs...

 

link to the sticky in the v8 section of this forum>>> https://www.f150online.com/forums/v8...ram-07m08.html

 

ok, no check engine has came on, so no codes. with the truck in gear it has an obvious misfire. i unplugged a coil, one at a time to see if the miss gets worse or stays the same. the cylinder closest to the radiator on the passenger side seems to be the culprit. If i unplug the wire to the coil the truck does not run any different. I pulled the new spark plug and everything looks good. I switched coils with another cylinder and that cylinder is still the one that doesn't seem to be responding... could this be an injector, a bad plug (maybe something internal with it) computer.. etc.. i will try cleaning the mass air sensor to see if that makes a difference. just weird...

 

Sometimes, a plug gets cracked during installation

 

You can see if you have any pending misfire codes. Read the PM even if the CEL isn't on. Disregard any circuit codes you have set by unplugging the coil connectors.

 

guys, the reason i am doubting the plugs is because i had a miss before i installed the plugs yesterday. the miss is now real bad. i willl swap the plug with a working cylinder just to verify. would a bad injector do this?

i went to autozone and pulled the codes and it was all circuit/misfire related. i couldn't get the code numbers because the machine went dead when he unplugged it and he went off of memory.. frustrating. he wasn't sure of the numbers but we thought it was what i said above.

 

A leaky injector wouldn't but a plugged one would.. If the plug is good. I think it's time to check compression.

 

Leaking injector absolutely can cause it to run rough. It can even take out then engine (bend rods) by trying to compress a liquid.