Error codes P0171 and P0174

[Jsmith10000]

Hello again. I just wrote up a how-to on changing the fuel pump on my 09 Ford Edge and I was elated to get the car up and running again but unfortunately it seems life wants to take another jab at me. I just got my car back on the road after changing the fuel pump in my Edge and everything ran great and still does but here's the problem. It's now showing a engine service light and when I hook up the reader it gives me the codes P0171 and P0174 which are 'running too lean' on banks 1 and 2. To further this new mystery is that when I'm just starting to accelerate or when I'm at cruising speed and I slowly give it some gas, a diesel sounding rattle comes from the engine. If I punch it a little or press harder it clears up the noise but the codes come back every time I clear it. It doesn't seem to affect engine performance either which is odd. I cleaned the MAF sensor and ran seafoam through 1 tank and no change. Any ideas to this mystery? I might just take it in to the dealer later but for now I like self maintenance routes the best. Thanks for the help.

[WWWPerfA_ZN0W]

One would think fuel injector issue right away, right? But it could be a bad coil(s) also. See if the info in this thread helps:

http://www.fordedgeforum.com/topic/17128-2008-ford-edge-se-error-code-p0171-p0201-p0301/

If it is a coil, doesn't seem like the situation has gone far enough yet to take a look at a faulty PCM possibility, but should keep that at the back of the mind.

 

Could be timing/phasers also, but then some related code should pop up.

[autom8r]

JSmith,

 

The lean condition on both banks simultaneously suggests the vacuum leak. Any vacuum leak would admit more air into the engine causing a lean condition. If it were one bank or the other, I'd chase the oxygen sensors. It still may be the oxygen sensors, but both going bad at the same time would be rare. The oxygen sensors may throw a separate DTC code (BMW does) indicating that the sensor is reporting slowly or late, not sure Ford does this.

 

Inspect the intake tubing between the throttle body, MAF, filter box and the resonators for loose connections/cracking. It may also be a leaking PCV hose.

 

Of course it may be the coils too, but I'd look for a vacuum leak first.

 

I liked your write up on the fuel pump. I was surprised that the pump could be replaced through the passenger compartment rather than dropping the tank.

 

Good luck!

[Jsmith10000]

Thank you for the information. With your assistance I have discovered 2 problems that caused this to happen and I fixed both and now the car is as quiet as a kitten and passes people on the interstate like a Cheetah lol. That new pump coupled with this great V6 and AWD makes for very speedy and responsive acceleration. I will list the 2 problems and what I did to fix it below.

 

Problem 1

There was in fact a disconnected vacuum hose. I think that the dealership that I had to drop my car off at when it originally broke down failed to reattach all of the vacuum hoses after doing their troubleshooting. I discovered a vacuum hose that runs from the back of the black plastic intake to a hose that connects to the brake booster was not connected properly. There's a joint in the hose directly behind the battery and it wasn't pushed in all the way. (fig. 1) I was just resting on the opening of the joint instead like as if someone was going to push it back on but didn't. I alao noticed that the other end of the brake booster hose that connects to the mair air intake on the other side of the MAF sensor wasn't pushed in all the way either. (fig. 2) After I reconnected the hose and pushed the other in all the way the diesel engine rattle disappeared from acceleration but the car kept throwing the codes. (Note: Both pictures are taken after I fixed it. It's just for reference.)

 

Problem 2

Since the codes kept coming back it dawned on me that the computer learns how your engine runs and adjusts according to what it knows about the engine parameters.I figured maybe it was still looking for my old pump (pressure readings) or it was still trying to overcorrect from the air leak. Either way I figured I could jump start it by forcing the computer to relearn everything. So I just simply disconnected the battery for 10 minutes and then the computer would have to relearn the engine. Afterwards I took it for a test drive and the car ran good but shifted rough. After about 15 minutes of driving through town, and then on the highway, it started to shift super smooth. Just to make sure the codes wouldn't come back I drove it to work and back which is 50 miles round trip and they never came back and I haven't heard the rattle since I first reconnected the brake booster hose. So all in all it's back to its like new feel and performance. Thanks again.

Edited December 7, 2015 by Jsmith10000

[WWWPerfA_ZN0W]

Good info, and glad you got the issues taken care of. Probably the right thing to do to let the PCM relearn if nothing else works, see if the problem resolves.