P0171/P0174 - System too lean (bank 1 & bank 2) - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

blazzin1 · 05-23-2021, 05:37 PM

My 2010 SS LS3 M6 (FBO) is throwing codes P0171 & P0174 - System too lean (bank 1 & bank 2). Seems to still run good, except I did notice that when I'm pulling up to a stop light and take it out of gear, it will idle up really high, like around 1800 rpm. What's weird is that once the car rolls to a complete stop, the idle will drop down to normal. I've inspected pretty good for any obvious vacuum leaks, and couldn't find anything. Any recommendations on what to look at next???

PaulsSS · 05-23-2021, 08:31 PM

Good place to start is the fuel trims, and fuel pressure

Mouse330 · 05-25-2021, 03:59 PM

MAF sensor. Disconnect it and see if there's a change
Have you made any changes to you intake system? Throttle body?
Gas quality?

DavidH · 07-18-2021, 11:25 AM

I'm currently trouble shooting the same thing. Same codes and that high idle when stopping. I've replaced the injector orings and manifold seals, still persists.

Run a vaccum test or smoke test. You can build a smoke tester for cheap with a pickle jar, soldering iron, and two hoses. I ran this test, a boost leak test, and had no issues. My conclusion is pointing toward something electrical (MAF/o2 sensors), or the fuel pump.

Have you tested fuel pressure at the schrader valve yet?

Has the MAF been cleaned? New intake installed?

Do you have access to a code scanner that will show long term fuel trims and see o2voltage?

G8One2 · 07-18-2021, 12:24 PM

Is this a stock car? Modified? What mods if any?

DavidH · 07-22-2021, 05:22 AM

Another item to check would be exhaust manifold gaskets. I checked mine yesterday and multiple bolts were finger tight. I believe this can cause a leak and induce additional air before the O2 sensors. In pair with this I am seeing a very erratic reading from the front o2s.

If you have access to a DTC scanner I would monitor fuel pressure at the rail during prime and idle, O2 sensor voltage during open loop, and long term fuel trims

05-23-2021, 05:37 PM	#1
blazzin1 Drives: 2010 2SS/RS R6P Join Date: Nov 2008 Location: St. Cloud, FL Posts: 4,845 View My Garage	P0171/P0174 - System too lean (bank 1 & bank 2) My 2010 SS LS3 M6 (FBO) is throwing codes P0171 & P0174 - System too lean (bank 1 & bank 2). Seems to still run good, except I did notice that when I'm pulling up to a stop light and take it out of gear, it will idle up really high, like around 1800 rpm. What's weird is that once the car rolls to a complete stop, the idle will drop down to normal. I've inspected pretty good for any obvious vacuum leaks, and couldn't find anything. Any recommendations on what to look at next???

07-18-2021, 11:25 AM	#4
DavidH Drives: 2010 Camaro 2SS Join Date: Jul 2021 Location: Chillicothe, Oh Posts: 138	I'm currently trouble shooting the same thing. Same codes and that high idle when stopping. I've replaced the injector orings and manifold seals, still persists. Run a vaccum test or smoke test. You can build a smoke tester for cheap with a pickle jar, soldering iron, and two hoses. I ran this test, a boost leak test, and had no issues. My conclusion is pointing toward something electrical (MAF/o2 sensors), or the fuel pump. Have you tested fuel pressure at the schrader valve yet? Has the MAF been cleaned? New intake installed? Do you have access to a code scanner that will show long term fuel trims and see o2voltage? Last edited by DavidH; 07-19-2021 at 04:52 AM.

05-23-2021, 08:31 PM	#2
PaulsSS Drives: 15SS Camaro Join Date: Dec 2020 Location: US Posts: 346	Good place to start is the fuel trims, and fuel pressure

05-25-2021, 03:59 PM	#3
Mouse330 Drives: 2011 2SS, 2006 GMC Sierra Join Date: Jul 2019 Location: MA Posts: 245	MAF sensor. Disconnect it and see if there's a change Have you made any changes to you intake system? Throttle body? Gas quality?

07-18-2021, 12:24 PM	#5
G8One2 Drives: 2014 Camaro 2SS Join Date: Feb 2015 Location: Metro Detroit Posts: 492	Is this a stock car? Modified? What mods if any?

07-22-2021, 05:22 AM	#6
DavidH Drives: 2010 Camaro 2SS Join Date: Jul 2021 Location: Chillicothe, Oh Posts: 138	Another item to check would be exhaust manifold gaskets. I checked mine yesterday and multiple bolts were finger tight. I believe this can cause a leak and induce additional air before the O2 sensors. In pair with this I am seeing a very erratic reading from the front o2s. If you have access to a DTC scanner I would monitor fuel pressure at the rail during prime and idle, O2 sensor voltage during open loop, and long term fuel trims