Hi group....
I have a 06 f150 with the 4.6. 130,000 km or about 85,000 miles. K&N filter, Evolution programmer set on tow. Everything else is original.

The truck runs good when the engines cold. As soon as it starts to reach operating temp it starts to missfire, stumble, run rough. After sometime it does turn on the check engine light and give a P0174 code. Sometimes on the highway if I keep it at a steady speed it seems to run fine. Sometimes not.

Things I've done....

I've checked by feel for a vacuum leak. All the hoses seem to be in good shape. Even the PVC at the back of the engine.

Changed the fuel filter

Removed and cleaned the MAF sensor

Cleaned the PVC valve...it didn't seem to be sticky and rattled fine...What I did notice when the truck was running I pulled the PVC hose off the PVC valve and was very surprised by the amount of vacuum!! When I did this the engine died almost immediately. Normal??

I came back from a 6000KM trip to the mountains a couple months ago. The truck ran like a champ the whole time. I gave it an oil change and about two days after this problem started. I used 10w-30 oil. I've always ran that but know it calls for another weight.

I know there's a list of possible issues it could be. I hope I can tap into the experience here and get this fixed before taking it in to the shop and over paying for the repair! ANY help would be great!!

 

10w30 is the wrong oil. Use the search feature to find more info on p0174. This seems to be a common topic.

 

Thanks...I've read pretty much every post. For the most part people are getting codes for lean on both banks. None have posted that the engine runs fine when its cold. I thought that may narrow down what the problem could be.

 

I have the exact same problem on my 04 screw. mainly acts up when warm. most noticeable at 1800 rpm. and the light finally came on with a p0174 code. help!!!!