Accuracy: Torque Pro Fuel Economy vs vehicle information display / odometer / trip computer

[CVTCivic]

Hi guys,

is someone using the Fuel Economy plug in from Torque Pro? I had it running for a few trips and the fuel consumption (l/100km) seems realistic, but it's always a bit off to what the odometer of my car says.

Aren't both just read data from the ECU? How is there room to interprete things or give different data, if they just use ECU data?

Also the average speed is a bit off, as you can see here:

[Ecky]

Wow, am I late to this post!

The reason you're seeing an accuracy discrepancy is that Torque Pro's default way of calculating fuel economy assumes the engine is always running 14.7:1 AFR. Its calculation is based on, essentially, RPM x load x displacement, with an adjustable offset to account for different volumetric efficiencies.

Why this doesn't work, is that most engines vary their AFR with temperature, when at high load, and even when operating under cruising conditions - they swing back and forth between slightly rich and slightly lean because the catalyst works better this way.

There is a way to create a custom PID in Torque Pro that can calculate fuel economy via either injector pulse time, like an Mpguino does, or by adding an AFR reading from a wideband O2 sensor as part of the calculation. I recall finding this on Insight Central some years back but didn't bookmark it. I'll take a look later today to see if I can find it, and post it here.

In the mean time you can probably correct it to "close enough" by adjusting the offset value, hidden in the Torque settings menu.

[CVTCivic]

Originally Posted by Ecky

...In the mean time you can probably correct it to "close enough" by adjusting the offset value, hidden in the Torque settings menu.

Thanks a lot for your detailed reply. I changed the fuel trim adjustment within the settings of TorquePro to 2.0.

Setting description: for people who believe their fuel mileage is off by a small amount - this allows you to adjust it. A value of 1 \=\= no adjustment, 0.9 mens lower, and 1.1 means increase.

Now it's still slightly off, but better. During my last trip, the numbers were almost identical:


(passenger took the photo):


And at the end of the trip, numbers were slightly inaccurate, but I think this is as close as it can get:

[redpoint5]

Yeah, mine is way off in the truck, but I've been too lazy to adjust it yet. It's reading much more optimistic than reality, though the instantaneous seems believable.