MFD shows incorrect engine status

[carz89]

Occasionally (I would say about 10-15%) of the time, the MFD in my Prius shows the wrong engine status. For example, sometimes during the latter stages of engine warmup, when I can definitely hear and feel that the engine is on, the Energy Monitor screen will show the engine is off, with no energy flow to/from the engine. At the same exact time, the instantaneous MPG on both the Consumption and the Energy Monitor screens will show a number less than 99. This isn't a "split second" thing either, as it will last for a minute or more.

Does my Prius have a split personality? The left side of the MFD brain is correctly calculating the MPG as less than 99 (proving that the engine is running). At the same time, the right side of the MFD brain thinks that the engine is off.

I'm thinking that this is a bug in the software (common to all Prii), or that there is a minor defect in my Prius' MFD system.

Anyone else experience inconsistencies with the MFD engine status?

[efusco]

The cartoon on the Energy screen is not an accurate representation and what you're observing is normal...the threshold for showing the ICE operating or energy flow are not 100% accurate and, as you've observed, the ICE maybe running at a low idle but no arrows will show on the screen.

If you really want to know what's going on you should invest in a ScanGuage (see Priuschat Shop)

[echase]

While this is a totally normal, I'm not sure it is actually inaccurate. The engine is running, sure, but do we know that energy is flowing from it during that state? The screen alleges to show energy flow not ICE state. You could also add a tachometer, or do one of Hobbit's many mods.

[qbee42]

The MFD does not show engine status; it shows power flow. The engine can run without power flowing to the battery or wheels.

Tom

[carz89]

Originally Posted by qbee42

The MFD does not show engine status; it shows power flow. The engine can run without power flowing to the battery or wheels.

Tom

If that's true, then it seems like a waste. I've seen the engine running, with no indication of energy flow, and the battery only at 5 or 6 bars. If the computer decides that the engine should run to warm itself up, then why not turn the MG and charge up the battery too? Given the same amount of throttle, the engine would heat up just as fast if it also charged the battery.

What bothers me is that I can't figure out a reason for the apparent inconsistency. I pay close attention to my MFD, probably glancing at it for a split second a few times a minute. Like I said, I've witnessed my described situation only about 10-15% of the time. Usually, the MFD shows what I expect. During engine warmup and the battery less than full-charge, I'll see energy flow from the engine to the battery if the car is still, or energy flow to the wheels for propulsion.

[richard schumacher]

In this case the engine is probably running to finish heating itself or the catalytic converter to optimal operating temperature. The battery is evidently already at its optimal state of charge at that time, so further charging would reduce its lifetime by some trifle. If the engine is running anyway one might as well drive the car at that time, to get some useful work out of it.

[hc167]

I obviously do not designed the prius. but base on my observation. I think when engine is on while there is no energy flow. that usually mean that the computer of prius detect that the engine is not hot enough and need to run the engine to make sure it reach the normal operating temperature. This piece of energy is waste. So this will happen more often in winner then in summer. of course this also mean that you are burning gas. and therefore, mpg will slowly reduce.

[Rest]

Here is something that may be an error. When I drive in that sweet spot, no arrows, and watch my SG2 the battery SOC goes down some. This tells me battery power is being used but it shouldn't be when there are no arrows showing.

[Leo]

Originally Posted by qbee42

The MFD does not show engine status; it shows power flow. The engine can run without power flowing to the battery or wheels.

Tom

Yes, I've seen many times where I am stopped for a red light, the engine is not running, the car is not moving, but I see an energy flow (arrow) running from the battery to the wheels. This usually happens when the car had been warming up the catalytic converter before ICE shutdown. I know the engine is not running because I experience the "shudder" when the ICE sheds its momentum and stops.
I suspect that it's actually showing energy running to something else from the traction battery, but I have no idea what is really happening.
Initially I thought the car was heating up the catalytic converter electrically, but I now know this doesn't happen (but I think it might be a good idea...)

[Sheepdog]

I have learned that when you are in stealth with no arrows you still are using a little battery energy. How much exactly I dont know but it is some.