verytalonted

Ok My F150 (03 4.6 FX4) started to make a "howling/moaning" noise at around 800 rpm when I would be sitting still at lights or sitting in a parking lot but the noise would stop if I gave it a little rev, but with time sitting there it would return. I once pinpointed the noise to be coming from the intake, I pulled the filter while it was running and put my ear near the MAS (Mass Airflow Sensor) and heard the noise coming from in the intake) That lasted a few weeks. On a 3 hour road trip my truck had the "Service Engine Soon" light come on right before I was about to leave, I pulled the negative cable to reset it, and went on my trip. On the way back I pulled over to get some fast food, and notice a whistling noise (think turbo spooling up noise) echoing off the fast food places wall and it was dependant on my RPMs, and I didnt remeber installing a turbo (haha, joke). The drive-thru was taking too long so I turned my truck off. When I turned it back on the familar amber glow turned on too ("Service Engine Soon" light). I continued my trip back home and had Auto Zone run the codes for me the next day. P171 and P174 were the codes (Left and Right engine bank running lean). The Auto Zone guy told me it was most likely the MAS and that this was a common problems with Fords (must have been a Chevy/Dodge guy). I went home and cleaned the heck out of my MAS (sprayed it with the special cleaner and never touched it) and the other sensor in the rubber acordian snorkle (By the way what is the sensor?) and reasembled it all and reset the computer to erase the code. When I turned it on it was more of the same. So I bent over and bought a remen MAS from the parts store, and replaced the MAS, but when I turned the truck on again no change.

So now the truck whistles (the howling has stopped) and the SES light is on and the truck stutters and stumbles when sitting at a light for too long, but seems fine when moving at regular speeds??? Is it safe to drive my truck???

Any help would be awesome!!! Sorry about being long winded, just wanted to give you guys everthing.

jrbaker09

the other sensor is an intake air temp sensor, i am going through basicly the same problem that you are with your truck and i am a ford certified tech, that feels kinda stupid at this point i think i have it narrowed down to a vacuum leak i am going to check the vacuum going to the heat and a/c controler tonight if you find anything please let me know and ill do the same.

verytalonted

Do you (or anyone else) have a pic of all the vacuum lines (like a diagram) I think I will start searching for a leak next. And not the under the hood one because the one is unreadable for me (look like terrible water damage which is weird because it is a plastic sticker?) but any body got a good Vacuum diagram?

verytalonted

Also will I hurt my truck Permanently if I drive the truck like this????

Trapper

If you both go to NAPA and buy a PCV hose and replace it you'll find your problem will be over. It is a common fail item on all Tritons and when you get both codes, the hose will cure the issue about 90% of the time. They get cracks and holes at the back corner of the hose and you'll go nutz trying to find the problem.

verytalonted

OK so replace all the hoses/lines that are vacuum and or intake related?

Trapper

Only the PCV hose needs replacing.

verytalonted

Got pics?

I replaced all my vacuum lines with rubber tubing instead of that old brittle hard plastic things. Still having "issues" with the truck.

Tell me more about the PCV valve and hose?

verytalonted

What about the IAC or EGR??? could this be a cause for my "hot cam" noise and terrible idleing?

verytalonted

bump