P0171 and P0174 Bank 1 & 2 lean

[Aspen03]

These 2 codes just popped up this evening on my way home from the grocery. I have no running issues (stumbling, roughness, miss, etc), no impact to mileage, starts normally, acceleration/power is normal.

Any clues as to what might throw these? It is a 2003 EB 5.4 4x4. Scheduled maintenance is up to date and no other known issues as far as motor goes. Current sitting at 241506mi.

Vacuum looks good on scan tool so I figure the next logical place to check is MAF though I don't expect it to be dirty, it was cleaned and a motorocraft air filter was put in just before winter. I did pull the tubing off just to clean crap off everything so it's possible something post MAF isn't sealed or has come loose. Motorcraft fuel filter has maybe 10k on it and no odd noises from fuel pump.

I'll probably drive the Navigator to work tomorrow and dig into this on my days off Wed/Thurs as well as look into the suggestions from my other thread about a vibration.

 

[Hamfisted]

My guess would still be a vacuum leak. Since it's both banks the typical culprit is that rubber PCV line connector on the rear of the intake manifold, or something towards the center that's affecting both banks. The computer can compensate for a lot of vacuum leak, but it'll still throw those codes. Do you have a smoke test machine ? That's a sure way to find it. Since you say you have no drivability issues right now, that kind of eliminates fuel pump/fuel pressure issue causing it.


Mechanics Smoke Test Machine on Amazon






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[Aspen03]

I don't have a smoke machine but planning to add one to the collection. The navigator has a vacuum leak that interferes w the air vents at moderate throttle. It was fine this winter as it was almost always on defrost anyway but will be troublesome for the ac. Weather is nice now so it's much more pleasant to tackle these little things.

Any idea what vacuum should be on these? When I had my regal I had a guage pod with a couple aeroforce interceptors and an analog boost/vacuum gauge. I could always tell how things were running w a quick glance because I knew where things should be at any rpm/tps position for the most part.

I ended up driving it today just because it ran fine last night and didnt want to take car seats out to leave for my wife from her navigator. I cleared the codes this morning and it has been through 3 drive cycles, about 53mi of mixed driving and they haven't returned. I'll still look into it of course but may have been a fluke. Guess we'll see soon enough.

 

[Old Guy]

Mine did just that. The vacuum hose from just in back of the throttle body to the egr valve rotted out and had ma bad vacuum leak. Get n the new hose assembly from Ford. Trying to piecemeal it will dive you nuts. (pun not intended).

 

[tedallen]

I have a 2004 Navigator and I had issues with the climate control defaulting to blowing through the defrost vents only. There were no codes being tripped. My issue were a couple of short sections of vacuum line on the passenger side of the engine bay back near the firewall to the inboard lower corner of the control module with all of the connectors going into it that is mounted on the firewall. There is a small black plastic vacuum tee that has 3 rubber vacuum lines coming into it that then connect to small plastic vacuum lines, one going through the firewall, presumably to the automatic climate control foe diverting of the air vents. Another runs back behind the battery into the vacuum canister located between the battery and the passenger fender well. The third one connects into a vacuum source.

I think I paid $2-$3 For a foot or so of rubber vacuum line and fixed my issue with maybe 6” of it. I suffered with it through almost a year before finally deciding to figure out what the issue was and found it in 10 minutes. Most of that time was getting tools out and getting the 2 bolts out of the engine shroud over the throttle bode, intake, etc. Hope this helps.

Ted

 

[Aspen03]

I assume the same is at fault on the navigator. Someone has messed around with vacuum lines once in that area from the looks of it and probably just made it leak from somewhere else moving all of that around. I will probably spend the $ to redo all of that, we'll be keeping the nav for a good while unless something that's $4k+ goes wrong. It's in great shape other than a few random things like this.

 

[getdealtwith]

I had the exact same issue with the vents, tedallen is right. On your Navi, inspect the small vacuum line that is connected to your heater control valve and the lines coming out of the firewall near the PCM.

On the Expedition, I would still inspect every single vacuum line coming off the intake manifold starting with the elbow piece Hamfisted mentioned.

 

[Aspen03]

Smoke machine being delivered tomorrow so I can get these 2 issues knocked out. I now have an intermittent miss and the code returned so well know soon enough where the leak is.

Navigator has a fun new problem, replaced all ride height sensors (back was bad, driver front was "sticky" and the passenger I just replaced because why not since the others were) drove perfect for about 300 mi and when I parked it now it sits in its kneel position and won't ride even with compressor running. Ha. These things... the wife loves the air ride though so we'll be tracking this one down

 

[Hamfisted]

Yeah, when you get your smoke machine, blow smoke into the compressor's air intake and look for where it comes out in the suspension system. Works there too.






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[Aspen03]

Smoke machine arrived this afternoon, it made VERY short work of finding the leak. I'm pretty sure it took longer to unbox. Is that line part of a larger set, a quick google shows a couple different options.

smoke was pouring out of the underside of the elbow. A couple tight wraps of super33 patches it up enough it no longer stumbles at warm idle. I didn't bother to take off the elbow because it was very brittle and would have probably crumbled in my hand.

That was exactly my plan as far as the nav suspension goes. I'm not really sure it is or is just a leak, maybe the compressor. It worked perfectly fine until it just didn't air up after parking the last time. I haven't had time to tear into it. Kids bday parties, end of school, etc have been eating up time off the past couple weeks.