Hi Everyone
I've been looking and couldn't find a good MAF test, so I though I'd post this.
1) First, you need an OBD2 reader that can read SAE codes (ie a base minimum of Intake Air Temperature (IAT), Air Flow Rate and RPM.
2) Connect your OBD2 reader and get:
a) The RPM your engine is ticking over at
b) The IAT
c) The Air Flow Rate
You can measure various RPM values if you want by logging data and looking at it via a spreadsheet.
3) Now use the Air Density calculator on the following page to calculate your air density at your elevation:
http://www.stealth316.com/2-air-fuel-flow.htm
4) Now calculate the mass air flow by using the Mass Air Flow calculator on the same page. I used a NC of 100% and a DR of 1.
5) Compare it to what you got from your OBD2 reader.
As an example, I used my OBD2 reader to get the following:
Air Flow rate: 19.9 g/sec
Air Temperature: 34 degrees Celcius
RPM: 2687
I then calculated my air density using a sea level air pressure of 14.7 psi and an air temperature of 34 degrees Celcius. The air density works out to be 32.556 g/CF.
I then calculated what the air flow SHOULD be using a default density ratio of 1 (non turbo) and a natural capacity of 100%, I get 6178.4 grams per minute.
Now, if I take the air flow rate of what MY MAF was telling me, I get:
MAF Flow Rate = 19.9 x 60 = 1194 g/minute.
From here, I can see that my MAF is telling the ECU that 1194g of air is flowing per minute when, in actual fact, 2687 g/minute is going through the engine.
As the MAF is telling the ECU that less air is going through, not as much fuel is injected and , as such, I am getting "too Lean" trouble codes at the O2 sensors (P071 - Bank 1 too lean and P0174 - Bank 2 too lean).
Hope this helps a few people
Here's where I purchased my OBD2 scanner for those who don't have one (do your own research though):
http://www.palmerperformance.com/products/pcmscan/index.php
For those who want to create a hybrid solution and save some money, look here:
http://www.discoweb.org/forums/showthread.php?t=18487
Instead of me paying $531 for a new MAF, I now only pay $170 if one dies.
Cheers
Erron
I've been looking and couldn't find a good MAF test, so I though I'd post this.
1) First, you need an OBD2 reader that can read SAE codes (ie a base minimum of Intake Air Temperature (IAT), Air Flow Rate and RPM.
2) Connect your OBD2 reader and get:
a) The RPM your engine is ticking over at
b) The IAT
c) The Air Flow Rate
You can measure various RPM values if you want by logging data and looking at it via a spreadsheet.
3) Now use the Air Density calculator on the following page to calculate your air density at your elevation:
http://www.stealth316.com/2-air-fuel-flow.htm
4) Now calculate the mass air flow by using the Mass Air Flow calculator on the same page. I used a NC of 100% and a DR of 1.
5) Compare it to what you got from your OBD2 reader.
As an example, I used my OBD2 reader to get the following:
Air Flow rate: 19.9 g/sec
Air Temperature: 34 degrees Celcius
RPM: 2687
I then calculated my air density using a sea level air pressure of 14.7 psi and an air temperature of 34 degrees Celcius. The air density works out to be 32.556 g/CF.
I then calculated what the air flow SHOULD be using a default density ratio of 1 (non turbo) and a natural capacity of 100%, I get 6178.4 grams per minute.
Now, if I take the air flow rate of what MY MAF was telling me, I get:
MAF Flow Rate = 19.9 x 60 = 1194 g/minute.
From here, I can see that my MAF is telling the ECU that 1194g of air is flowing per minute when, in actual fact, 2687 g/minute is going through the engine.
As the MAF is telling the ECU that less air is going through, not as much fuel is injected and , as such, I am getting "too Lean" trouble codes at the O2 sensors (P071 - Bank 1 too lean and P0174 - Bank 2 too lean).
Hope this helps a few people
Here's where I purchased my OBD2 scanner for those who don't have one (do your own research though):
http://www.palmerperformance.com/products/pcmscan/index.php
For those who want to create a hybrid solution and save some money, look here:
http://www.discoweb.org/forums/showthread.php?t=18487
Instead of me paying $531 for a new MAF, I now only pay $170 if one dies.
Cheers
Erron
