Strong engine braking in D

Hi David,

I have a 2016 Prius with a scan gauge. When I'm going down a long downgrade, with the traction battery fully charged, the engine definitely speeds up either in D or in B to provide some engine braking, but my scagauge shows that gas is being consumed. The MPG seems to vary between around 50 and 100 MPG. Unless my scangauge is lying to me, this makes me question your statement that the Prius will turn the engine with no fuel to dump energy.

Greg

 

Many of us with Gen3s have seen ScanGauge showing 0.02 gallon/hour when it should be 0. This seems to be an artifact in the communications between the car and the gauge, not real. When the car clearly is burning fuel, I have not seen less than 0.20 gal/hour, which often translates to 150-300 MPG. Other times, we see true zero fuel use.

On downgrades, my 2014 Subaru sometimes shows the same thing you mention now, in situations where my 1997 Subaru showed perfect zero fuel use. These cases seem to also be associated with the ScanGauge showing lower trip MPGs than the car shows, but I haven't seriously dug into what is really happening.

 

You guys are too young! What happens if you tell your computer to divide some number by 0? Modern computers have a sub-routine that stops you from doing this, but simple or older computers will try! And lock up attempting to produce a result of "infinity"!

Sooo, the Scangauge manufacturer puts a small value that always appears in fuel consumed. So it won't/can't try to divide by zero. Even when no fuel is being consumed, the Scangauge will indicate some is. It's a rather small number so doesn't affect accuracy.

 

I though the ScanGauge could show zero fuel used, then simply show its maximum display number (9999) to avoid divide-by-zero.