Engine code P0170 and P0174 System Lean Banks 1 & 2

Tiny
JKOSTUR
  • MEMBER
  • 1996 CHEVROLET TAHOE
  • 188,348 MILES
I have a system lean problem that I cant figure out. Ive checked all vacum lines installed new fuel filter and ran injector cleaner as well as cleaned the MAF. My suspicions is it is the MAF itself that is bad but not sure. Can anyone shed a little more light or is there something else I should check?

Sunday, September 8th, 2013 AT 6:20 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
Make sure there are no leaks around the intake. Also, check fuel pump pressure to make sure it is within the manufacturer's specs. Finally, check O2 sensors to make sure they are working properly.
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Sunday, September 8th, 2013 AT 6:28 PM
Tiny
JKOSTUR
  • MEMBER
  • 3 POSTS
Fuel Pump is new and ive check all of the air intake, Also looks like both Upstream 02 Sensors are new but the down stream looks old. Is there only one downstream 02 sensor? Or is there 2. I only seen one when I was under there.

Thanks for your input I really appreciate your time
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Sunday, September 8th, 2013 AT 7:21 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
I believe there is only one down stream. Even though the upper ones look new, you should check them.
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Monday, September 9th, 2013 AT 3:04 PM
Tiny
MADMIKE1735
  • MECHANIC
  • 951 POSTS
Do you have access to a scan tool that has live data? If so, check the short term fuel trims. Do this with engine running. Spray carb cleaner around your intake, etc and see if the voltages change on the fuel trims. Also, drive this with the scanner hooked up, and check your calculated load reading. When you have the gas pedal floored, such as pulling a hill, or passing a car, your calculated load should read above 90% of not, replace the MAF.
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Saturday, September 21st, 2013 AT 7:52 PM
Tiny
JKOSTUR
  • MEMBER
  • 3 POSTS
Don't have a scan tool. I unplugged the MAF while engine was running and vehicle died. I'm not sure what that means but the voltage on the sensor looked ok.
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Saturday, September 21st, 2013 AT 8:03 PM

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