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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Incorrect MAF Readings

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Author Topic: Incorrect MAF Readings
bira
Member
Posts: 6
Post Incorrect MAF Readings
on: December 30, 2014 (GMT)

Calculating airflow on my 2013 Mustang GT (302), assuming a volumetric efficiency of 0.8, @ 6000 RPM it should be about 420 CFM. However, the Mass Airflow Rate shows almost 2000CFM!
I have the unit “toggle” set to use CFM. Any ideas?

Edit: Adding some log info.

RPM           CFM          VE (calculated)
5184.75    1558.80    3.440561836
5294.50    1168.72    2.526110327
5201.00    2030.86    4.468481074
5510.50    2074.97    4.309110254
5514.50    1221.66    2.535192866
5330.25      297.19    0.638048077
5226.25      504.22    1.104070176
5133.25    1150.43    2.564688199
F-150Torqued
Member
Posts: 437
Post Re: Incorrect MAF Readings
on: January 18, 2015 (GMT)

I’m not sure your Torque readings are off at all.

I recently tried to verify the MAF CFM readings on my 5.4L F150 – and screwed the calculations up so badly that I unnecessarily bought a new MAF sensor – just to find the new 200.00 one produced the very same readings. THEN, I realized I had left barometric pressure, manifold vacuum, and exhaust backpressure completely out of my hasty calculations!!!

Your 302 CI engine has a 2.0972 CF displacement and, being a four stroke, draws one breath into all cylinders once every four revs. So, with no vacuum, no intake restriction and no exhaust backpressure (((302/144)/4)*6000)= 3145.83 CFM. I’m not sure what your VE (calculated) consists of, but I don’t think your Torque readings are all that far off.
F-150Torqued
Member
Posts: 437
Post Re: Incorrect MAF Readings
on: January 18, 2015 (GMT)

All you have to do is read my last post above to determine I don’t know what I’m talking about!!!!! A four stroke draws a breath of air into each cylinder EVERY OTHER revolution, not every 4th rev. So as you can see, that’s why I spent 200 dollars for a new MAF sensor and found out it read the same as the old one. Maybe one day I’ll figure it out.

Sorry I can’t help.
vwchuck
Member
Posts: 1
Post Re: Incorrect MAF Readings
on: January 22, 2015 (GMT)

CFM is volumetric flow rate. What is logged is your mass flow rate. Very different. You need to convert from mass flow to CFM. The mass flow looks to be in lbs/hr FYI.

F-150Torqued
Member
Posts: 437
Post Re: Incorrect MAF Readings
on: January 22, 2015 (GMT)

Thanks @ vwchuck;

Lbs / hr ??? I knew something was seriously wrong with my attempts to calculate a meaningful number for comparison to my MAF readings on my Torque App. But I wouldn’t have a clue how many lbs would be in a cubic foot or meter, or even if it would be the other way around. LOL. I knew there was a reason I kept the old MAF I changed out – without helping the problem BTW! Now, if I suspect it again, I can just swap it back and see if that does any good.

But, I’m the type – it bugs me when I can’t figure something out! Your info gave me something to work with.
manrob30
Member
Posts: 3
Post Re: Incorrect MAF Readings
on: May 25, 2015 (GMT)

Hi guys i just installed racing meter and i cant find hp voltage and maf widgets
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