Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
i have a problem with my 2008 silverado 1500 4.8 v8 4x4
codes p0171 p0174
what have i done :
replaced MAF
Replaced Y piece + cats
Run smoke test : no leaks.
Fuel pressure is 42 psi engine on running.
should be 55 to 65 says GM
Did you smoke test the intake side of system and exhaust side as well. Looking at fuel trims for long term looks like a leak in exhaust system. Blow smoke in exhuast and see if it leaks out anywhere. (Mainly around o2 sensors, exhaust manifold, egr valve and valve pipe etc that's in front of o2 sensors. On a few occasions a fuel injector or two can contribute to it as well. But you would see rich numbers for short term. Since short term is ~9 and long term is 29 for both banks would say area to look at is from front o2 sensor back to rear o2 sensor(Stripped out o2 sensor bung or cross threaded, air injection pipe cracked or not reattached etc.
I’d remove the vacuum hose off the regulator and see if your fuel pressure jumps up to spec. Do a snap throttle and see if you’re pressure holds (small initial fluctuation is fine).
Can you current clamp the pump?
Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
