engine codes

[Sam]

Hi all. I just got a used 2007 Stage 3, red with white racing stripes and only 8000 miles on it. I'm loving it. Only thing is that the "check engine light" has been on. A buddy of mine hooked up a computer to it and got the following two diagnostics:

(1) P0171 - system too lean (bank 1)
(2) P0174 - system too lean (bank 2)

Any idea what the likely cause of these codes would be? I was told it could be the fuel pressure regulator, the C02 sensor, or could be nothing at all and just a result of the car's computer throwing a code because I disconnected the battery briefly. Any info would be greatly appreciated.

-Sam

[TRAKPAK#19]

I'm no mechanic but lean maybe the guy was running 87 octane. I use 93 octane in my Supercharged Roush 427R. I really don't know if I could use mid grade but I never chance it. I know you don't wanna use the lowest octane for sure............Thats probably not it but may help you in the future. Even my Lexus has a 93 octane tune for performance. It says in the manual to use Premium Octane Fuel.

[mln385]

The grade of fuel could be an issue be sure to run 91 minimum 93 best on the supercharged cars.
Other thing to look for is does your car have an off road x pipe under it? If you have an aftermarket intermediate pipe installed that could be it since you are throwing both left and right codes.

[Sam]

Thanks for the input, guys. The exahust is just the factory installed Roush high-performance exahaut, and I'm running 91 Octane (just filled it up last week).

[mln385]

Well if it is all stock then it is still under the 3/36k bring it to the dealer under warranty, the ECm may need a reflash , odd that you get both banks as a lean condition. Could be a fuel filter that would be the easiest repair. But only 8k on the clock , I have also seen where an aftermarket cold air induction could throw this code.

[3ponies]

No CAI installed?

[pikapp]

Wifes GT Vert with CAI and dyno tune used to get those same codes. The tune was richened up a bit and we haven't had any problems for over a year. One of the causes, as told by my tuner, is the weather. Depending on the conditions, it can cause the engine to go lean a bit, enough to throw the CEL. The tunes on the cars are very conservative, but adding some rich to it has kept the CEL from showing up thru all the seasons so far.

[06stage2]

I had that same issue with my old 06 F250. Cleaned the MAF and codes went away. Might be worth a try.

[kevnstac]

I agree with MAF sensor, as my 2005 F150 did the exact same thing. But like said above with only 8k on the clock it may still be in warranty.

[ROUSHGUY]

There is also some known problems with the Fuel pressure sending units too... but i would start with the maf first

[TRAKPAK#19]

You call Roush Performance. They are very accessible for someone to have a conversation with. I always get a person that is knowledgable and cares about my questions and my car. They probably have a good idea of what's going on with your car. Good Luck.

[06stage2]

I agree with MAF sensor, as my 2005 F150 did the exact same thing. But like said above with only 8k on the clock it may still be in warranty.

If it has an over oiled CAI (which is fairly common) it doesn't take long for the MAF to get saturated and cause it to throw codes.

[Sam]

Hey, guys. Just wanted to bring this thread back up to the front to update you on my latest development. Hopefully others might find it useful too. On the first day warm enough to not freeze my fingers off since Christmas, on backed my car out of the garage and took a detailed look under the hood. What I found surprised me. I have attached two pictures to show what I found - one is a larger shot of the engine area with the suspect vacuum leak circled; the second picture is a zoomed-in view with the suspect leak indicated by an arrow. It appears to be a small outlet or connector off one of the main vacuum hoses feeding into the intake. There is a residual ring of cracked rubber around the base of this connector, indicating that it used to either be connected to something else by a rubber hose, or it was capped by a rubber cap, either of which broke off.

This definitely fits into the category of a source of "non-metered" air, whcih I was told could be the problem. Since you are all so familiar with these engines, just what the heck is this little connector on the larger vacuum hose, and should it capped or connected to something else? I put a piece of tape over it, and the lean codes have not come back since.

[mln385]

It goes to the black canister below with the missing vaccum line shown. This is the boost bypass while the engine isn't under load it bypasses the boost built while idling.

[Sam]

It goes to the black canister below with the missing vaccum line shown. This is the boost bypass while the engine isn't under load it bypasses the boost built while idling.

Wow, thanks very much, mln385! I was wondering about that open port. You just saved me about $200-300 at the Ford dealership to tell me the same thing. With only 8000 miles, the question is, how the heck did that hose fall/break off.....................................? A mystery.

Thanks, again.

[mln385]

Are you the original owner? If not some people had a trick to bypass it in order to stay in boost all the time instead of bypassing it.

[pikapp]

It goes to the black canister below with the missing vaccum line shown. This is the boost bypass while the engine isn't under load it bypasses the boost built while idling.

Also, per my setup, the vaccum line is attached to the outlet closest to the front of car (the one that is capped in the photo). The non-capped outlet is the one that should be capped.

[Sam]

Are you the original owner? If not some people had a trick to bypass it in order to stay in boost all the time instead of bypassing it.

That's a good point. I bought it used from a guy in FL.