I am using the Torque app on my phone which does not give me fuel pressure. I wrote a PID for the app, still didn't work. I used my buddy's scan tool, but at the time, the pressure was good. My problem seemed occur under moderate load while the truck was hot, but still intermittently.

I did replace the fuel pressure regulator on Sunday, my codes have not come back yet. So far, the gas mileage seems better too.

 

[QUOTE=pounder90;14200093]I am using the Torque app on my phone which does not give me fuel pressure. I wrote a PID for the app, still didn't work. I used my buddy's scan tool, but at the time, the pressure was good. My problem seemed occur under moderate load while the truck was hot, but still intermittently.

I did replace the fuel pressure regulator on Sunday, my codes have not come back yet. So far, the gas mileage seems better too.[

Where did you get the Bluetooth adapter for the torque app?
How much was it?
It plugs into the dlc I assume
Sorry, I know this is of no help to your problem

 

That's what I was thinking based off your finds as well as mine.

 

[QUOTE=vaper;14200108]I bought one of the elm327 adapters from amazon. It was cheap (~ $11). Works great. Plugs into the OBD2 port (dlc?).

 

dlc data link connector

 

[QUOTE=pounder90;14200435]Thanks pounder, I think I'll buy one.

 

I was ready to call it fixed. Ran 3 days with no codes. The light came back on this morning. It was p0174 logged and p0171 pending. I really thought that the fuel pressure regulator had fixed it since I had not been able to clear the codes that long previously. I put the scan tool on, but the STFT and O2 readings were normal. Back to the drawing board.

 

Weird, I had no codes for 2 days driving to work. I carry My scan tool in the truck. When I got to work - No codes, no lights.
2 hours latter when I checked the codes (just to play with the scanner) I had both banks lean codes P0174 etc.
Now how can that be?

 

That is normal. If you have the ability to check pending codes, sometimes they will show up there, but haven't triggered the SES light.

I am pretty sure that I do not have a vacuum leak. I have done several smoke tests. If I disconnect the line going to the vacuum canister, the system is still holding vacuum for atleast 20 mins after running. I am going to focus on the fuel pressure next. Does anyone know what thread is on the fuel rail where the shrader valve is attached? I removed the shrader valve, but it looks smaller than 1/8 NPT. It looked like 27 tpi with the thread gage.

 

The fuel rail Shrader valve is meant to test from.
Why remove it?
Same thread outside as a tire stem.
Test gauge hoses have the correct thread to mate.
Good luck.

 

This does not make sense to me
If both banks are coding lean, the stft should be out of limits?
Did you try a reset?

 

The PCM sets the P0171 and/or P0174 code based on the sum of the STFT and the LTFT. If the sum exceeds ~30% the code is set, first as a pending code. If it sets in two successive "trips" the CEL will be illuminated.

There are actually 9 cells of STFT (based on a 3 X 3 grid of load vs rpm).
The scan tool only displays the STFT cell the engine is operating in at that time. You need to look at the FF data to see what the fuel trims were, as well as the load and rpm, when the code was set.

 

Ok I see,the ff data stft will be out of limits when the code/codes were set.
All my scanner has is freeze frame data, I guess I assumed that was what he was looking at.
Didn't know about the 9 cells 3x3 grid, I am always learning new stuff on here
Gonna have to read up on that
Thanks pdqford

 

I want to thread a fitting into the fuel rail and cowl mount an analog gage to monitor while driving.

I disconnected the battery and let the computer reset. Running out of ideas.

I haven't figured out how to catch the FF data with the Torque app. I can monitor real time data and haven't seen a lean condition. When I turn on data logging, the files are always too large to email. Even if I catch the lean condition when the code is sent, I am still hunting for the cause.

 

I'm getting the same codes right now too... but mine lopes intermittently too.. runs ok once revved up though.

I checked the fuel pressure at O'Reileys auto parts. They will loan you the gage for free. (You have to pay for it, but you get all your money back when you return it). I did the test right in their parking lot. It only takes a few minutes.

Good luck, I hope you'll find it soon.