Constant Codes coming back P0104, P0171, P0174

[05capepony]

After my car sat for the winter storage I have been plagued with constant codes of P0174, P0171 and P0174. Replaced MAF sensor, Cleaned Throttle body, replaced injectors and fuel filter. Returned to stock tune and reloaded Bama 87 and 91R tunes with no results. Car starts right up, but it seems that when it reaches operating temp is where the trouble begins. Ran great before stored for the winter and can't get a handle on what the issue is now. Don't want to keep throwing parts at it. Also gas mileage seems to be about 6-8 mpg less than before the trouble started. Any ides would be great. The only thing I did after the winter was change the valve cover gaskets.

 

[Dino Dino Bambino]

Buy an ELM 327 Bluetooth OBD 2 scanner that plugs into the under dash port, download the Car Scanner app onto your smartphone, pair it to the scanner, and view/record some live data such as O2 sensor voltages and short/long term fuel trims. It'll help us zero in on the possible culprit.
It seems that you have a lean condition and the ECU is trying to compensate by dumping in more fuel. Since both cylinder banks are affected, I'd say the most likely cause is a vacuum leak. Check all the hoses/pipes that are attached to the intake manifold, including the intake pipe itself, for cracks/breaks/leaks. You might want to hire a smoke machine to trace any other possible leaks around the intake manifold.

Which ELM Scanner would you recommend?

I'd recommend the Total Car Diagnostics unit that I have.

 

[05capepony]

Which ELM Scanner would you recommend?

 

[05capepony]

Buy an ELM 327 Bluetooth OBD 2 scanner that plugs into the under dash port, download the Car Scanner app onto your smartphone, pair it to the scanner, and view/record some live data such as O2 sensor voltages and short/long term fuel trims. It'll help us zero in on the possible culprit.
It seems that you have a lean condition and the ECU is trying to compensate by dumping in more fuel. Since both cylinder banks are affected, I'd say the most likely cause is a vacuum leak. Check all the hoses/pipes that are attached to the intake manifold, including the intake pipe itself, for cracks/breaks/leaks. You might want to hire a smoke machine to trace any other possible leaks around the intake manifold.


I'd recommend the Total Car Diagnostics unit that I have.

Prob stupid question. I changed out the valve cover gaskets this spring. Could a leak from the gasket be causing the codes?

 

[VBSTANG06]

Dino knows his stuff I agree with possible vacuum leak.

 

[Dino Dino Bambino]

Prob stupid question. I changed out the valve cover gaskets this spring. Could a leak from the gasket be causing the codes?

Yes that's possible 'cause vacuum would be lost from the crankcase.

 

[Robert Larimer]

Yes that's possible 'cause vacuum would be lost from the crankcase.

I thought the crankcase had positive pressure? I have a catch can that separates the oil from the crankcase gases that come through the PCV valve right?

 

[CrashDevine]

After my car sat for the winter storage I have been plagued with constant codes of P0174, P0171 and P0174. Replaced MAF sensor, Cleaned Throttle body, replaced injectors and fuel filter. Returned to stock tune and reloaded Bama 87 and 91R tunes with no results. Car starts right up, but it seems that when it reaches operating temp is where the trouble begins. Ran great before stored for the winter and can't get a handle on what the issue is now. Don't want to keep throwing parts at it. Also gas mileage seems to be about 6-8 mpg less than before the trouble started. Any ides would be great. The only thing I did after the winter was change the valve cover gaskets.

Replace the plenum gaskets / PCV for vacuum leaks

 

[Gabe]

The '05-'09 cars are known for throwing all kinds of weird codes when the alternators go bad.
And funniest part, the alternator tends to test OK when that happens