18-12-2016, 10:56 AM
The MAF sensor would under-read with contamination. The dirt on the hot wire means it doesn't cool correctly as it's covered in dirt. This makes it think less air is flowing through than there really is.
This thread posted by Pro-Steve (HDI Tuning) is a good read here
https://www.theywhoshallnotbenamed/forum...st-the-MAF
Snippet of checking the air flow rates on a good maf.
"What values should you see in PP2000:
Without a remap you should see approximately 850-900mg/r at full load in third gear around 3000 RPM. With a stage one, air flow will be a bit higher due to the extra turbine drive, you'll see over 900 mg/r, nearer 950 mg/r max. With a stage 2 you should see something like 1200 mg/r max depending on how much you've wound the boost up. If you see massive figures like 1400 mg/r you've likely got a boost leak, this results from the turbo having no restriction so it can suck loads of air through the MAF.
Whilst I'm at it, I may as well let you know what to expect on idle with no load. With EGR: 250-300 mg/r. With EGR unplugged 450-500 mg/r. If you have lower than 250 then it's possible your EGR is jammed open.
As a lot of people use other diagnostics systems which give readings in g/second or kg/hour here's some simple calculations:
To convert from grams per second to mg/ rotation: ((MAF reading in g/s) x 60000 ) / (2 x (Engine speed in RPM)) = air mass in milligrams per intake per cylinder
To convert from kilograms per hour to mg/ rotation: ((MAF reading in kg/hr) x 1000000 ) / (60 x2 x (Engine speed in RPM)) = air mass in milligrams per intake per cylinder."
This thread posted by Pro-Steve (HDI Tuning) is a good read here
https://www.theywhoshallnotbenamed/forum...st-the-MAF
Snippet of checking the air flow rates on a good maf.
"What values should you see in PP2000:
Without a remap you should see approximately 850-900mg/r at full load in third gear around 3000 RPM. With a stage one, air flow will be a bit higher due to the extra turbine drive, you'll see over 900 mg/r, nearer 950 mg/r max. With a stage 2 you should see something like 1200 mg/r max depending on how much you've wound the boost up. If you see massive figures like 1400 mg/r you've likely got a boost leak, this results from the turbo having no restriction so it can suck loads of air through the MAF.
Whilst I'm at it, I may as well let you know what to expect on idle with no load. With EGR: 250-300 mg/r. With EGR unplugged 450-500 mg/r. If you have lower than 250 then it's possible your EGR is jammed open.
As a lot of people use other diagnostics systems which give readings in g/second or kg/hour here's some simple calculations:
To convert from grams per second to mg/ rotation: ((MAF reading in g/s) x 60000 ) / (2 x (Engine speed in RPM)) = air mass in milligrams per intake per cylinder
To convert from kilograms per hour to mg/ rotation: ((MAF reading in kg/hr) x 1000000 ) / (60 x2 x (Engine speed in RPM)) = air mass in milligrams per intake per cylinder."
