DIY: BMW Air Flow Meter Testing

Video tutorial on how to testing and troubleshoot a BMW air flow meter which is the design of an early style mass air flow sensor. This is a Bosch Motronic system and is also found on other vehicles besides BMW such as Alfa Romeo, Volkswagen, Porsche, Mazda, etc. Similar procedures may be applied to other vehicle, but refer to OEM specifications to ensure the values are the same. I also did two types of testing on the potentiometer which were done by both the resistance and applying voltage to the circuit. I would recommend doing the voltage test vs the resistance because it is a much more reliable test. The resistance test will always show the mildest of contact issues and magnify the readings. A faulty air flow meter can cause issues with starting, idle, fuel economy, throttle hesitation, throttle flat spots, and emissions. This particular tutorial was done on a 1984 BMW 733i equipped with a 3.2L inline 6 cylinder M30. Website: http://4diyers.com Facebook:   / 4diyers   Google Plus: https://plus.google.com/+4DIYers Twitter:   / 4diyers   Instagram:   / 4diyers   Tumblr:   / 4diyers   Pintrest:   / 4diyers   Air flow meter refurbishment:    • DIY: BMW Air Flow Meter Refurbishment   Pinout functions: 6 - ground 9 - input voltage from DME 7 - output voltage from DME 22 - temperature sensor Tools/Supplies Needed: -3/8" ratchet -10mm socket -standard/flat screwdriver -razor knife -multimeter -9v battery -9v battery plug -2 small connectors Procedure: -first start by removing the rubber intake elbow going from the air box -ensure that the car is up to full operating temperature -disconnect the O2 sensor on the firewall -start the vehicle, while running, push the door inside the air flow meter inwards -if the vehicle's idle increases while smoothing out, the air flow meter does need to be cleaned or calibrated -next remove the air flow meter complete from the vehicle -allow it to cool down because it will hold the heat for a little while and this can affect the testing of the temperature sensor -the multimeter will be required to check the resistance -my probing pins #6 and #22, between the temperatures 15-30°C (59-86°F), the reading should be between 1450-3300ohms -you can also use a heat gun or hair dryer to determine if the temperature sensor is functional -if there is an issue with the temperature sensor, unfortunately there is no part which can be purchased to replace it, but you can replace it with another sensor from a different air flow meter assembly or purchase another used unit or a new unit -next moving onto the potentiometer starting with the resistance test -probing pins #6 and #7, use the multimeter on the resistance setting -open and close the door to view the values either increase or decrease, if there is drops along the way, there is the possibility of either having a dirty contact or the contact has worn spots -moving onto the next test using voltage to determine the quality of the potentiometer -using a razor knife, cut the silicone around the plastic cap and remove it prying with a standard/flat screwdriver -install the smooth connectors on the battery plug, then connect the 9v battery and plug onto pins #6 and #9 -using the multimeter on the voltage setting, put on the one test probe on the arm and the other on the ground or pin #6 -open and close to view the voltage increase or decrease and determine if there is any drops along the swipe of the potentiometer -if there is any drops or extremely low voltage when the door is fully open, the swipe arm needs to be adjusted or have the contacts cleaned Thank you to all those who watch my videos and support my content. Don't forget to subscribe to my channel for future tutorial videos and like my video if you found it helpful. New videos are always being uploaded every week! © 4DIYers 2013 All Rights Reserved No part of this video or any of its contents may be reproduced, copied, modified or adapted, without the prior written consent of the author.