SCScrew

For the last few weeks I have had a CEL coming on from time to time. I had it checked at AutoZone and it gave a P0174 & P0175 last week. We cleared the codes and today I got a P0174 code again. The truck has 124k miles and is running great. I have noticed a few times in the mornings that it will idle fine for a few minutes but when I come to a stop the idle will seem a little low but not terribly bad.

In the last 3 months I have had new plugs put in, the throttle body has been cleaned and the o-ring underneath it replaced, the MAF has been replaced (Firestone thought this was the issue but I disagreed), the fuel injectors have been cleaned, the #8 coil & injector were replaced due to a P0308 code, the FPDM has been replaced and now I am at a loss. I don't use oiled filters and just replaced the paper air filter. I got to looking around this evening thinking that the only thing left is a vacuum leak and I found what appears to be a vacuum hose that runs from the passenger side just to the left of the throttle body and runs around the back side of the intake and then connects to a part that is fixed to the firewall just behind and to the left of the brake booster. The pictures below show the hose that I am referring to. (I am not talking about the hose that connects to the side of the air intake/throttle body). The reason I am concerned with this hose is because it is very dry and coarse and when I felt around it my fingers were extremely black. What is this hose called and could it possibly be my problem? Also, how hard is it to replace and do I also need to replace the fittings that connect this hose to the intake and the part on the firewall? What would you call those fittings? Are there any other hoses that could also be the root of my problem?

Thanks for any assistance with this. The truck is running good but I am getting tired of the CEL coming on every few days but I know that vacuum leaks can be hard to track down.

SCScrew

BassAckwards

Let me check all your codes real quick, but usually a vacuum leak, although will cause a rough idle, would cause a rise in RPMs not a drop. I'll get back to you here in a second with ideas.

BassAckwards

Here is what I have found.

P0174 <-click here

You are running lean on Bank 2 sensed by the O2 sensor.

So it's either a problem with the MAF sensor (which you already replaced so not likely) or a vacuum leak.

The one in your pictures is indeed I believe the Brake Booster Vacuum Line.

There is also a Vacuum line for your PCV Valve and for your Automatic locking hubs if you have a 4x4.

One way to tell if there is a leak is spray Throttle Body cleaner on the vacuum lines and if the idle changes, then that line has a leak.


Another thought came to my mind. Did you use Throttle Body Cleaner to clean your throttle body, or Carburetor Cleaner? There is a big difference and you must use Throttle Body Cleaner

SCScrew

Thanks for the quick reply and for looking into this for me. I did make sure to use CNC Throttle Body cleaner on the throttle body and I took it off to clean it and used a rag and an old soft bristle toothbrush so I don't think the throttle body is the cause but I have been wrong before. I am suspecting a vacuum leak but don't want to just start throwing money at replacing unnecessary parts. I use my 4 wheel drive a good bit and have not had the problem that so many have had with the IWEs going bad due to bad vacuum so I don't think that line would be my problem. I am suspecting the PCV line or brake booster lines. Any idea how much these would cost to replace?

SCScrew

I reset the PCM last night by disconnecting the battery for a while and the code cleared. I went out of town today and after driving about 200 miles the CEL came back on and this time I noticed that it came on right as I got on the gas pretty hard to pass another car (I'm guessing this is due to a rapid increase in vacuum pressure in the intake). The truck still runs good but I am going to try to find a shop nearby tomorrow that has a smoke machine to see if they can locate any leaks. I hope it isn't the intake manifold gasket leaking.

BassAckwards

If its a vacuum leak that's as cheap as it gets! All you do is replace a rubber hose! Super cheap and easy! Could even be one of you vacuum lines just accidentally came off!

SCScrew

I dropped the truck at a garage this morning and they did a smoke test and found no leaks. They called and said that since I am getting both a p0174 and a p0175 code that maybe my bank 2 O2 sensors need to be replaced. They also said that it could be a clogged catalytic convertor. Should I let them change oxygen sensors first? Does that sound like a reasonable diagnosis? I don't want to change sensors and then have a CEL pop up in a few days. Sensors aren't cheap but convertors are very expensive. Any advice so I can call them in the morning.

savage87

look man those arent your problems at all. you have a bad cam phaser. take it to ford let them diag it and i bet my money on it! im a ford tech had a expedition come in same exact code idle low and had another code that tripped on the customer as well from a driveability concern. replaced the "driverside" bank 2 cam phaser a bam problem solved! anytime people run a long time w/o changing their oil or run cheap oil or jiffy lube so to speak oil filters it will begin to sludge up or the filter will come apart. the motorcraft synthetic blend is hated on by alot of people but its good stuff. i have customers that are couriers w/ 1,000,000+ miles on their vehicles all oil changes by us and still running strong. the key is stay on a maintenance schedule 3 month or 3k miles whichever comes first!

savage87

reason i brought up the oil issue is due to the cam phaser being a hydrolic component its run off oil pressure. another big reason for changing your oil is because these overhead cam engines do not have cam bearings its a machined groove in the head once its whiped out by lack of oil pressure your head or heads along w/ the cams are trash! it can get pricey quick.

kozal01

iTrader: (2)

Please tell me how a phaser would throw a lean code? Im throwing in the BS flag on that.