I've been reading a lot of the threads about spark plug issues with F150s but I'm trying to find some additional help.

I changed my spark plugs this past Thursday. None broken, whew. Put everything back together but the car started idling super rough, ~600 RPM with entire truck shaking. No check engine light or anything of the sort. Decided not to drive it so on Friday took another look at it after reading that the COPs might not be on correctly.

Took the COPs off and checked each new spark plug; they are all fine. Put the COPs back on and the car got a little better, idling at ~750 RPM but the truck is still shaking. Have been reading that it could be the COPs that are bad? Any additional help would be much appreciated. Also, if the recommendation is for COP replacement, where is the best place to buy these? I've seen a set of 8 for $40 and I've seen each one for $12 so not sure where to go.

 

What kind of plugs did you use ?? Did you use dielectric grease during your installation ? double check all wires to each COP.

 

also check https://www.f150forum.com/f4/fuel-pu...-yours-152908/

 

Used Motorcraft plugs. Ordered 8 new boots, arriving tomorrow will install.

 

How many miles on your truck? The coils "should" have been good for 100k miles, but once broken loose from the plugs and re-installed the boots are subject to damage. And I'd agree to stay with the motorcraft plugs. And not positive, but I think I've read on here before those cheapo coils are no good....so best to stay with the proven ones. Not worth the hassle of a breakdown or damaging something else.

 

DONT. use cops u find for 40.00 a set (Chinese) they will eventually will short to head or cause more issues mine did .and OR can ruin cats or have a cell light.. had to replace with OEM or better quality accel.? Lessons learned

 

I bought Motorcraft WR6131 for $6.11 each that is OEM correct?

 

I just replaced all 8 boots and the engine is still idling roughly at 600 RPM. It feels like the engine is trying to breathe and is suffocating, and I got a check engine light... ran the code and got P0174 so there is a vacuum leak but what should I be checking? I cleaned the MAF sensor with special cleaner but still same thing. Ideas?

 

It sounds like you may have accidentally taken a vacuum line off. Or damaged one when doing the plug change. First carefully look all over the motor for a loose line. If not found, then try to take one line at a time and follow it from end to end.

Did you do anything else while doing the plugs? Like take off and cleaning throttle body? Another thing to check/fix is the foam on the bottom side of the air filter. Just a few ideas.