P0171 1997 Ford Expedition

[Eugenia Bermudez]

I have check engine light on. Checked codes and it has P0171
Freeze Frame reads
Fuel Sys 1-. CL
Fuel Sys 2-. N/A
Calc Load-. 38.0 (%)
ECT-. 174 (°F)
STFT B1-. 15.6 (%)
LTFT B1-. 15.6 (%)
STFT B2-. 9.4 (%)
LTFT B2-. 13.3 (%)
Eng. RPM-. 1090

Any comments?

 

[Hamfisted]

Vacuum leak probably from PCV elbow hose or something in that area. If you can not find it fairly easily you can definitely find it with a smoke tester.

https://www.amazon.com/AutoLine-Pro-Automotive-Detector-Diagnostic/dp/B07JVT1NG2/ref=sr_1_5?crid=1BQI20MDZQ3PT&dchild=1&keywords=mechanics+smoke+machine&qid=1615329311&sprefix=mechanics+smoke,aps,180&sr=8-5

 

[Tommie]

I agree... here's a cheaper alternative:

 

[Tommie]

rev the engine past 1200 RPM steadily and see if your fuel trims improve to lower single digits. If so then def a vacuum leak. PVC pipe is biggest culprit but the smoke test will make it all obvious. Rock auto has good prices for your needed parts, 5% coupons are littered all over the internet.

 

[Eugenia Bermudez]

When the check engine light came on the first time it had three codes P0171, P0174I, P0455 I took it to a shop and they replaced the MAF sensor and the mechanic cleared the codes and told me to let me know if that worked after driving it a while. I drove it and it was still not running right so I took it back and the mechanic and I took it for a drive. He told me that he couldn't hear or feel anything wrong and that I was probably just paranoid. I had another mechanic check it and he replaced the fuel filter. It ran better but I could still notice a problem. I personally replaced the PCV valve, purge valve and had the shop replace the purge solenoid. Each time I had something replaced it drove a little better then it would start losing power running bad again. I then took it to a mechanic that did a smoke test on it and smoke was coming out of EGR and he told me he couldn't do a proper smoke test until the EGR was replaced. He replaced it and and sent me on my way. 140+ miles later check engine light comes on. But before the check engine light came on I could tell there was something still wrong and I took it back to him at which point he told me it needed to go through it's drive cycles and that could be up to 200 miles. At 140 miles check engine light comes on and here we are

 

[Hamfisted]

Re-read the second post and find a new mechanic....

 

[Eugenia Bermudez]

So I took it to another mechanic and he said it's a bad fuel pump. Says it drops to 25psi under load.

 

[Hamfisted]

So I took it to another mechanic and he said it's a bad fuel pump. Says it drops to 25psi under load.

That can definitely be a contributing factor. It should hold 40-50 under load. Bosch makes a good replacement pump if you don't want to spring for a Motorcraft unit.

 

[Tommie]

Update us if that fixed it, when you did the PVC did you change the actual piping that goes to the back of the intake manifold as well? I'm sure it needs it if you didn't.

 

[Tommie]

Hey Hamfisted, I am chasing a low power issue in my 5.4 2v, I have 30 PSI at idle and with the FPR vacuum pulled it goes to 40 PSI, should my gauge be higher when I rev?

Also, Your sig always grabs my eye when you post LOL