Amazing how many parts were thrown at this vehicle to fix this simple problem. This is what happens when you do not know how to troubleshoot and start replacing parts based on symptoms alone. So follow along and let me teach you some fundamental tests that I use on every vehicle that has a low power complaint.

Engine Performance Diagnostics chapter 1 page 8

symptoms 50

  • low power
  • hesitation problem
  • surging and bucking
  • misfire
  • MAF sensor trouble codes
  • lean exhaust trouble codes (P0171, P0174)

fix 50

  • replace torn air intake tube behind the MAF sensor

test shown enh 50

  • How to use oxygen sensor signals at wide open throttle to identify the cause of a low power complaint
  • how to determine if the MAF sensor is producing the proper peak signals
  • How to properly test fuel pressure

Tools used

  • scan tool
  • pocket screwdriver

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(Chapter 12) Mass Airflow Sensor Testing

Related videos:

MAF and lean codes from a missing air filter (P0171, P0174, P0102):


How to identify and clean a dirty MAF sensor (Subaru):


How to identify and clean a dirty MAF sensor (Lexus):


How to test for a restricted exhaust (catalytic converter):


end faq

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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium. There is a 14 day free trial.

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!