CODEWITHSUNDEEP
automationobd-ii
A-dude
A-dude

Reputation: 171

Fuel Consumption and mileage from OBD2 port parameters.

I am computing my fuel consumption from OBD2 parameter. MAF to be specific and I am receiving data on per second basis. Here is an section of my data.

      TS    RS  EngS    MAF R   MAP    EL   TD Travel

14:41:22    31  932     1056    98  23978   12130
14:41:23    29  2084    2639    107 23210   12130
14:41:24    32  2154    3867    149 38826   12130
14:41:25    36  2426    4683    184 36266   12130
14:41:26    39  2391    3031    133   682   12130
14:41:27    40  1784    2794    132 30634   12130
14:41:28    42  1864    2853    140 30378   12130
14:41:29    43  1953    2900    132 29098   12130
14:41:30    46  2031    3017    135 29098   12130
14:41:31    45  2027    2969    126 20138   12130
14:41:32    47  2122    4253    174 42154   12130
14:41:33    51  2220    4722    183 20906   12130

Where TS : Time Stamp, RS : Road Speed, EngS : Engine Speed, MAF R : Mass Air Flow Rate, MAP Mass Air Pressure, EL : Engine Load, TD Travel : Total Distance Traveled

So basically from this data I am trying to compute my Instantaneous Fuel Consumption and The Mileage in KMPL. For that, Since The Data is per second i am taking MAF of each row and using this formula,

Fuel Consumption = MAF/(14.7*710),

where 14.7 = ideal air/fuel ratio, and 710 is density of gasoline in grams/L

So, this should give my consumption. and I am calculating the distance(in KM) from RS /3600. And further dividing distance by fuel consumption to get mileage. However the calculation is coming horribly wrong. The mileage of my car is around 14KMPL. Here are my results.

      TS    Distance (inKM) Fuel Consum(L)  Mileage(KMPL)
14:41:22    0.0086111111    0.1008355216    0.0853975957
14:41:23    0.0080555556    0.2519933158    0.0319673382
14:41:24    0.0088888889    0.369252805     0.0240726374
14:41:25    0.01            0.4471711626    0.0223628016
14:41:26    0.0108333333    0.2894246837    0.0374305785
14:41:27    0.0111111111    0.2667939842    0.0416467828
14:41:28    0.0116666667    0.2724277871    0.0428248043
14:41:29    0.0119444444    0.2769157317    0.0431338602
14:41:30    0.0127777778    0.2880878491    0.0443537546
14:41:31    0.0125          0.2835044163    0.0440910239
14:41:32    0.0130555556    0.4061112437    0.0321477323
14:41:33    0.0141666667    0.4508952017    0.0314189785

Can someone tell what am I doing so wrong that the computation is so wrong. As the formulas are simple there isn't much scope to do error.Thank You.

Upvotes: 0

Views: 3543

Answers (2)

Dhiren Biren
Dhiren Biren

Reputation: 530

Divide the MAF by 14.7 to get Grams of fuel per Sec next divide by 454 to get lbs fuel/sec next divide 6.701 to get fuel/sec multiply by 3600 to get gallons/ hr

other case GPH=MAF*0.0805 next MPG=MPH?GPH

Upvotes: 0

Troy Halm
Troy Halm

Reputation: 36

MAF is in g/s

MAF(g/s) * 1/14.7 * 1L/710g = Fuel Consumption in L/s Units

Speed (V) is in KPH (Km/hr) so V(Km/hr) * (1hr/3600s) = v KPS(Km/s)

so FC(L/s) / v (Km/s) = L/Km

you want Km/L so v/Fc so your final formula is KmPL = V * 1/ 3600 * 1/MAF * 14.7 * 710

Upvotes: 2

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