2000 V10 Excursion. 144K on it. Keeps throwing the P0174 code. Started with three codes, but once the system was reset the the only one to return is the P0174. Below is what it was when I first ran it.

P0174 System Too Lean (Bank 2)
P0135 02 Heater Circuit (Bank 1, Sensor 1)
P0155 02 Heater Circuit (Bank 2, Sensor 1)

Now I only get the P0174.

I have cleaned the MAF twice. I replaced the PCV hose. It had slight cracking, but I did pressure test it and it was fine. The jacked up part is that when I went to Ford to get the replacement hose, I was told its no longer available. Discontinued part. I find it ironic that one of the most common part failures and emissions issue would be discontinued. Maybe they just ran out of them

Anyway, I have checked everything I can think. Blown a few cans of brake cleaner all over the motor looking for a vacuum leak and cannot find anything. The intake tube is tight, and isn't leaking. Checked the PCV and cleaned it out as well. Its working normally. Only thing left is the fuel filter which I will install tomorrow at my shop. What else could I be missing?

The X runs normally, but I see a 2.5mpg drop as soon as the code appears after reset. A 20% drop in fuel mileage isn't going to cut it at the pump.

 

Also can someone verify the part number for the PCV hose by chance? I replaced mine with some high pressure fuel injection line just to be safe, but will try to source a factory line someplace if possible.

 

Well, I went ahead and installed the new fuel filter, reset codes, and within 3 miles the P0174 code is back. This is really beginning to tick me off. I also installed a new gas cap just in case. No help.

 

Here is my "Freeze Frame" info

DTC for which Freeze Frame was Stored P0174
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 78.04 %
Engine Coolant Temp 163.40 °F
Short Term Fuel Trim - Bank 1 -1.56 %
Long Term Fuel Trim - Bank 1 -2.34 %
Short Term Fuel Trim - Bank 2 24.22 %
Long Term Fuel Trim - Bank 2 12.50 %
Engine RPM 1,434.00 rpm
Vehicle Speed Sensor 18.64 mph

 

Can someone pull the part number off of this hose if possible.


The hose that is on my V10 looks nothing like this. Mine is just a standard rubber hose with no elbow. Just rubber hose from the PCV all the way to the throttle body.

 

I'm not a mechanic or tech.
appears there is an over fuel condition on bank 2 [ drivers side] so the fuel trim is leaning out.
Leaking injector, misfire COPs, trouble with wire harness, O2 sensor, grief with pcm?
Get a shop manual [ Alldata ] and systematically isolate the problem.
Wish I could guess right for you but thats the best I got.
Best of luck.

 

I was going to say "clean the MAF just to be sure" but after viewing that freeze frame data, I gotta agree with Zedrive. Something is way out of whack. However, I disagree with him on what is really going on.

Those bank 2 trims are WAY rich. Which means the system sees bank 2 as being very lean and is richening up to make up for it. So it goes as far as it can, and still can't get it right, so it throws the "too lean bank 2" code.

It's not a vacuum leak, otherwise BOTH banks would be trimmed way rich. And, it can't be a dirty or bad MAF, because again, BOTH banks would be trimmed way rich.

I would suspect an O2 sensor or the wiring. Wiring, especially with those heater circuit codes, even though they haven't come back.

Without spending a single dime, pull the O2 sensors and swap them.

Then check the fuel trims again or wait for a code. If it moves to Bank 1, change that O2 sensor. If it doesn't move, report back and we'll work on it more.

 

This is what I was leaning towards as well. I just can't see it being a vacuum leak without both the P0171 and P0174 codes being thrown.

Keep in mind that I have only owned this thing for a week, so having never pulled codes, they could have been stored from way back before the PO swapped in O2s to begin with.

 

Well, I think I found the issue. The driver's side O2 bung was replaced. It looks like the original one was stripped so someone booger welded a new bung right over the old one and only laid down about a 3/4" weld.

You can literally see light all the way through the bung, so my guess is that this is why the O2 was ready way too much oxygen in the system and throwing the jacked up code.

So, I pulled the Y-pipe out and will re-weld it and have it down in a few. I will report back if this fixes the issue. My only guess is that the previous owner did this when the O2s were replaced.

Look at this thing.

 

Jeez, I can't weld worth a darn, I would have tacked it and at least brazed it

 

Well, I fabricate and build offroad rigs for a living so the fix will be done right.

FWIW, That is just a **** poor install. I can only hope that a shop didn't do that. On closer inspection, the original bung had been cross threaded and was worthless. I am just finishing up putting it all back together and will hope that this fixes the issue. I should have just replaced the whole Y-pipe, but just want to see if this is the fix first. If it is, then a new Y-pipe will be fabbed into place at some point.

 

Well, it looks like this fixed it. Saw a remarkable difference immediately in mileage immediately. I usually average 11.5mpg on the same section on the 12mi drive home from my shop. I have reset the Lie-ometer each day to test it since I bought it. Well, tonight I got 14.9mpg on the same section. This is roughly a 60-65mph section on flat land.

I can completely accept that as my last X got similar mileage when stock.

 

Zedrive didn't look close enough and see those were positive. oops

 

The problem could very well be the DPFE sensor, EGR Differential Pressure Sensor...if truck is over five years and 60K this is often the problem.

 

Just to update it. The screwed O2 bung was the issue. Its now been four months without a code thrown and it runs perfect.