Does anyone know what the LOD (engine load) reading on the ScanGauge is actually measuring? What is its significance. particularly in trying to achieve higher MPG?
<div class='quotetop'>QUOTE(Doc Willie @ Jul 27 2007, 12:45 PM) [snapback]486204[/snapback]</div> I believe it is this data you're asking about and without your prodding, I wouldn't have bothered to find out myself. So tnx! Calculated Engine Load California Air Resource Board (CARB) defines this as airflow divided by peak air flow. Peak air flow may be adjusted for altitude via barometric means if available. For diesel engines, the number is current output torque divided by peak output torque at current rpm. We have noted that vacuum leaks can have dramatic effects on this value.
<div class='quotetop'>QUOTE(glenk @ Jul 30 2007, 03:42 PM) [snapback]487565[/snapback]</div> So it is an inverse the air flow. I assume this means there is an air flow sensor somewhere in the intake system. If it's really sophisticated (which I doubt) it corrects for barometric pressure/altitude.
<div class='quotetop'>QUOTE(Doc Willie @ Jul 30 2007, 10:22 PM) [snapback]487776[/snapback]</div> The airflow sensor is a few tiny pieces of wire that show a change in density as the air flows across the wires. It is very simple and most do not take into account the pressure. The Prius also has an Air intake temp sensor. The ECU tries to take into account the density of the air coming in and the temperature to determine how much gas to mix into the air stream when injecting fuel. This is the best I can do to explain how the system works. I know galaxee is very busy but he may be able to break the explanation down a bit more than I have. I hope this helps. D Rock
Yes, it's a "hot wire" air flow sensor. Place a thin wire in the air flow and drive a small current through it to heat it. Watch the voltage across the wire (changes with resistance). The air flow over the wire cools it. This changes the resistance which gives a voltage change. Works well over a limited flow range. Turbulence or a change in turbulence will mess up the calibration. This is why aftermarket "cold air intakes" are a "bad idea" . Some systems do have a separate pressure sensor. Not sure about the Prius. All also have an intake air temp sensor (which gives -some- indication of air density).
Newbie to both Prius and ScanGauge II here...I didn't see an obvious (to me) answer in this thread on how it helps with fuel economy, or why some folks like to have it as one of the four displayed fields on the ScanGauge. What would it tell me about how my driving habits are affecting my fuel economy...should I strive to keep it high...low...or just pick a different field to display since I don't know what it tells me?
Simple answer - you don't control the engine throttle, you control the "request for engine throttle". So you can use that reading to see how the system is using the ICE. Drive for minimal readings (more closed throttle on the ICE), which should give better fuel economy. The engine is actually more efficient at higher throttle openings/higher load, but that's in "gas guzzling" territory, which of course, we don't use. We drive so we don't -need- high load. I don't use that reading, I display engine RPM, l/hr, 12V battery voltage, and engine coolant temp.
