Engine issues regarding fuel and spark

[jetmech06]

I have an 05 Expedition with the 5.4 3V with 165k miles and lately I have had issues with driving the vehicle on the highway, when the vehicle kicks into overdrive and I go to accelerate, the vehicle shudders and kicks in the lower RPMs, If I turn the OD off the vehicle runs fine. I have replaced the 1,3,5,7 COPs when the codes have popped up. I have also noticed that the acceleration isnt there anymore. When the vehicle does this I do not get any codes or check engine light... Any Ideas?

 

[toms89]

Don't really have enough information but it sounds to me as if it is misfiring under load. This can be caused by many things.

Misfire code does not necessarily point to the cops. It could misfire due to improper plug gap, fouled spark plug, moisture in the plug well, bad or dirty fuel injector, improper fuel pressure, vacuum leak, etc......

Had the engine been washed recently??

 

[jetmech06]

No the Engine was not washed, But if your getting a misfire wouldnt the check engine light come one when having a misfire? I'll have to pull the plugs and take a look . I thought maybe a dirty injector as well. Thanks for the reply!

 

[toms89]

No the Engine was not washed, But if your getting a misfire wouldnt the check engine light come one when having a misfire? I'll have to pull the plugs and take a look . I thought maybe a dirty injector as well. Thanks for the reply!

Depends on the cause or circumstance and no, not necessarily.

More people are relying on the pcm to diagnose all issues when it does not. It can aid in diagnosis and if conditions are right it will point to a problem area. Many people assume it means a particular part is bad as well but this is not the case. Its up to the individual servicing the vehicle to understand what the code indicates and properly diagnose.

There are procedures and diagnostic routines to follow in the ford shop manual for each code.

I have had bad misfire in the past that the pcm never picked up on because it did not meet the conditions used by the pcm to set cel.


You mention replacing several cops as codes were set. How close in interval were these codes set? Months apart or back to back? Ongoing misfire codes??