Vane Air Flow Meter

Part 4 - 11th January 2004 

Engine Warning Light On

The AFM's needle was released at the Allan-Key's section and moved backwards till it never touch the circuit board before the engine starts to breath.


This is an experiment due to recent significant lost of mileage or fuel economy, extreme engine rough noise, some extra metallic noises etc.

After this is done and start the car. The engine warning light stays on between 5 seconds to 10 seconds. Each time the car is started but runs fine after which.

The ECU error log code is retrieved as described in Diagnosis System and found error code 31 - which 4AG-E 20Valve Engine Repair Manual says as "Vacuum sensor signal PIM". This is the MAP's vacuum sensor on 20vMAP (aka blacktop). This is however 20vAFM (aka silvertop) hence must translate to AFM Flap voltage instead.


Now it is know that when the car's starting key is put to "ON" position just before "START" the ECU will read as many signals from as many sensors it can so that it can deliver a proper starting fuel delivery.

From this exercise it is found that the AFM's needle needs to touch the starting to the circuit board and it gives 4 volts.

After the starts it likes to be around 3.1V or 3.2V although one other has been found to have 3.8V but that transplant was not 100% successful.

Oh finally - this is not the cause of low fuel efficiency. 


  1. AFM Breakdown
  2. Dismemberment
  3. Flap Tension
  4. Engine Warning Light On
  5. Warning / Tips - Buy Vane Air Flow Meter (AFM)



HOME - Technical Website for Acoustics, Audio and Car

  Malaysia Boleh 


Hit Counter