My trip computer is not accurate, showing better mileage than actual by at least 15%. On my last tank of gas I actually averaged 18.1 mpg, while my tc showed 21.5. Any ideas how to correct this? I have reset it and no improvement. I have even replaced the tc, and my service rep tells me not to expect a more accurate reading. Is this as good as it gets? Also, I am still looking for the little plastic cover that covers the trip computer display.
Many thanks,
Bob
I would guess that the problem is with the fuel flowmeter. Low fluid flow measurements tend to be tricky. The trip computer is only as good as the inputs.
The only fuel consumption mileage metric that matters is what you measure when you fill the tank.
DelJ
Quote:
Originally Posted by bobalvis
My trip computer is not accurate, showing better mileage than actual by at least 15%. On my last tank of gas I actually averaged 18.1 mpg, while my tc showed 21.5. Any ideas how to correct this? I have reset it and no improvement. I have even replaced the tc, and my service rep tells me not to expect a more accurate reading. Is this as good as it gets? Also, I am still looking for the little plastic cover that covers the trip computer display.
Many thanks,
Bob
My trip computer is not accurate, showing better mileage than actual by at least 15%. On my last tank of gas I actually averaged 18.1 mpg, while my tc showed 21.5. Any ideas how to correct this? I have reset it and no improvement. I have even replaced the tc, and my service rep tells me not to expect a more accurate reading. Is this as good as it gets? Also, I am still looking for the little plastic cover that covers the trip computer display.
Many thanks,
Bob
Somewhere along the line MB changed the trip computer as far as mileage readout is concerned, maybe 2002. My 00 430 would read actual mileage over the whole trip after reset. The reset would always start over at 6.6 MPG and go up from there. My 05 500 SE when reset only shows the mileage of the last 62 miles run. Why MB did this I don't know. Maybe Wolfgang can tell us!
We discussed the trip computer accuracy on Ken's M-Class list a while back and folks compared it with what was put into the tank. As I remember most folks got pretty reasonable results. The data input comes via the CAN-Bus from the 4ETS controller (wheel speed signal), engine controller and instrument cluster (fuel consumption). The cluster reads the fuel level. If there's a problem with the fuel level sensor in the tank it could lead to erroneous consumption figures. With sulfur in the fuel a tank after being filled up shows low or empty. Driving with that setup would presumably show fuel consumption figures which are too favorable.
The service manual only says it uses "average" fuel consumption, but not what kind of average. I checked on the webpage of the trip computer manufacturer, since taken down, and it explained the algorithm as "moving average". Maybe this was in regards to the 2002+ versions, not sure. When I measure it for comparision it's usually under 62 mi, so it would be the same figure for either method.
There must be a fuel flowmeter for the on-the-fly fuel consumption determination. Measuring the short term fuel consumption rate would be impossible if the system only measured fuel tank level.
DelJ
Quote:
Originally Posted by Wolfgang
...The data input comes via the CAN-Bus from the 4ETS controller (wheel speed signal), engine controller and instrument cluster (fuel consumption). The cluster reads the fuel level. If there's a problem with the fuel level sensor in the tank it could lead to erroneous consumption figures. ...
Linear Mode
