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Author Topic: Over reading fuel flow?
j721884
Member
Posts: 2
 Over reading fuel flow?on: July 15, 2019 (GMT)

Has anyone here used the Torque app to log data from the OBD port?

I have been logging some data from my Ford Fusion 1.6 TDCI, during a full accelration pull I have;

92.6 g/s MAF

552.8 cc/min Fuel flow

Assuming that the stoichmetric AFR is 14.46 and the fuel has a density of 0.8345 g/cc I have calculated the Lamda as follows;

552.8*60 / 92.6 * 14.46 * 0.8345 = 0.83

This gives a lamda of 0.83. In other words the ECU is putting more fuel in then it has oxygen to burn. I’m assuming a value like this would lead to plumes of black smoke, yet there isn’t any with my car. I think there is an error with the OBD reading. Has anybody looked at torque logs before? Any ideas why the fueling is so far off?

moreause
Member
Posts: 639
 Re: Over reading fuel flow?on: July 15, 2019 (GMT)

stoich value of 14.7 value is only in normal driving

for power the value change from 10 to 12 :1 depending on application

if you have it in you value check for the COMMANDED afr

j721884
Member
Posts: 2
 Re: Over reading fuel flow?on: July 16, 2019 (GMT)

Quote from moreause on July 15, 2019
stoich value of 14.7 value is only in normal driving
]>

Just to clarify this is a diesel engine. It is different. You tend to run lean all the time to prevent smoke.

Interestingly if I calculate the fuel flow from the MPG it is lower. Then it works out to be a lambda of 1.1

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