All,

So far I have replaced spark plugs (Due to miss fire code), replaced evap canister (due to another code). For the P0171 and Po174 I have put in a new MAF senor replaced the vacuum hose on the canister on the driver side firewall. Replaced both forward O2 sensors. and now I plan to put a fuel pressure meter on the fuel rails to see how that looks.


As far as the PIDs the long term fuel rail is stuck at 29.7. I have sprayed crab cleaner all through the engine compartment with no change in RPM. I did change the fuel pump about 18 month ago and the fuel filter 2x in the last 12 months.

The last 3 things I can think of are the fuel pump, the fuel injectors and the air intake gasket. This model had no EGR so that cannot be a problem.

Any easy solution to figuring out what this can still be without paying for any extra new parts?

Thanks in advance

-Todd

 

Oh yeah I read a lot about a vacuum elbow but mine does not seem to have it. a vacuum diagram would be great if anyone has one!

 

Did you ever figure out the root cause? Just got the p0171 and p0174 shortly after an oil change. Cleaned MAF without success, no vacuum leaks identified yet either. I switched from Dino to Synthetic.

2013 5.4 79k on the clock, new to me and I didn't get much from dealer on maintenance history.

Edit: Same results on the long term fuel trim, 29.7 bank 1 and bank 2 per the torque pro app.

 

MB,


I lost the codes after replacing the fuel pump again. I assume it was just not enough fuel or the correct pressure. This was the last straw for that vehicle and I traded it in for a 05 excursion with a 6.0L . So far so good with the diesel. I am not sure it was just my expedition or the year but I spent more time under the hood then with my family.


Hope the fuel pump suggestion helps. FYI if you ever change the spark plugs start spraying them down a few days before so they do not break off. I got all mine off but it too 2 days of spray and try to turn then wait and try again.

 

Thanks for the quick reply, I've been chasing a fuel demon in my excursion for a couple months which is why I have this one, lol. May get them both fixed at the same time and go back to the excursion, it's paid for.

Thanks again, will double check fuel pressure and see if I can align to symptoms.

 

I've been chasing down a P0171 & P0174 for a couple weeks.. just found my air filter can has a sloppy large rubber grommet on the bottom side for the IAT/MAF Sensor wires. It's in the right place for an air leak that can throw off the air/fuel mix to cause a lean condition. I think the grommet was only half in and fell out when I was changing the air filter.