MAF is possible, DPFE doubtful, if it's bad you will get EGR codes.

 

Add insufficient fuel supply to the list of possibilities.

 

At the risk of sounding stupid, how is that checked? And wouldn't that possibly throw another code?

Also, yesterday, engine cold, started it up, let the rpm's drop to idle, put it in reverse, forgot something in the house, put it back in park, and I heard a noise...kinda sounded like whoooooooooooo but not low pitched, sort of in between middle & high pitch. First time I heard that! Now, to me...that sounds like it could be a clue to the problem, but what do I know, I'm not a tech, I'm just trying to fix my truck with all of you guy's help. I know I shouldn't get discouraged about this, but I think most all of you know the feeling. I'm trying!

Please keep in mind I don't have any specialized tools, just sockets, wrenches, basic stuff.

This is a far cry from working on my 68 Mustang when I was in high school! Damn! And the car was only three years old at the time.

I appreciate and welcome the help! I'm not giving up yet!

Reloader

 

It's checked with a fuel pressure gauge.

I'm too lazy to review both threads - have you changed the fuel filter?

 

There are several indicators...

One is from the conditions under which the fault code was posted, data that is in the Freeze Frame.

Another is to measure fuel pressure under driving conditions, especially if the DTCs are posted under load while driving.

You can also watch the fuel trims for clues as to when and why the "lean" codes are being posted,

TSB 4-17-4 has more info.

 

The fuel filter has not been changed for a few years. I guess that's a bad thing. To be honest, I never thought about it.

 

I guess that means I should get a better scan tool to read the freeze frame and the fuel trims. And maybe a fuel pressure gauge.

 

When you go to the parts store for a fuel filter, "borrow" a fuel pressure gauge, they should have one in their tool loaner kit. You will at least be able to test the pressure at a low and high idle. Minimum 28, normal 35 to 40, pulling the vac line off the FPR will cause it to go up about 5 psi. If you don't have one, you will also need a clip tool to change the filter.

 

Hi guys, I know it's been a while, had a few familly issues. I've been trying different things then resetting the codes. I haven't been driving it that much and when I do, I've been keeping the mileage down and limiting the engine speed between 1500-1800 RPM's. The P0171 & P0174 codes are still there. I purchased a scan tool that does a lot more than just reads codes & resets them. so, here's what the snapshot shows:

Read Codes
P0171
$10 Generic
System Too Lean Bank 1
P0174
$10 Generic
System Too Lean Bank 2

View Freeze Frame
DTCFRZF P0174
FUELSYS1 CL
FUELSYS2 --
LOAD_PCT 25.5
ECT 345
SHRTFT1 4.7
LONGFT1 29.7
SHRTFT2 7.8
LONGFT2 29.7
RPM 624
MPH 0

All the sensors reported an OK condition reported by the scan tool. I do not know how to decipher what the freeze frame shows, Maybe someone here can.
Thanks for all your help so far.
Reloader

 

you have a vacuum leak.Major culprit is the PCV elbow at the back of the throttle body.

 

Just read the whole thing and see you check the elbow. It's leaking somewhere..

 

Yes, I replaced that whole line, new elbow & PCV valve. I don't suppose it could be something simple like the rubber gasket in the valve cover that the PCV valve pushes into? Probably not. I'm hoping it's not the intake manifold gaskets.

 

Hello. If u have cleaned the Maf sensor (using maf cleaner), changed fuel filter, checked plugs n wires, elbow at pcv, checked fuel regulator then it may be intske manifold gasket. Mine only acted up in temps below freezing. It threw code p01151 n my mech changed us n coil packs. Ran better except in freezing temps. Diagnosed bad intake gaskets which are in process if being replaced this week

 

Sorry changed plugs. I hate autocorrect!!!

 

PM being sent.