Exhaust While ICE is off on MFD ???

The MFD is not a real indicator of whether the engine is running or not. Someone installed an led to indicate engine running several years ago but I have not heard of anything similar lately.

 

I have oftened wondered myself why it doesn't always show on the MFD when the ICE is running. I have always assumed that it is just maintaining heat at such a low idle that it doesn't charge the battery or use it to propel the vehicle because it would be an unnecessary additional load on the ICE for the current conditions.

 

That display on the MFD shows energy flow within the system. Just because the ICE is running doesn't mean it's doing much. It may mostly be contributing heat. Also keep in mind that the MFD is only a crude approximation of what is actually happening in the system. CANview gives a better idea. The MFD misses short duration events and otherwise displays a simplified view.

Tom

 

Could you provide a few more details about your observations?

- speed
- how exhaust was observed

Bob Wilson

 

Hi All,

The MFD shows energy flow in the Drive Train. If the engine is not supplying any motive power, the line from it wont be lit up. The engine is also used for heating the cabin and in some circumstances its run to keep the catalytic converter hot (this actually reduces polution they say). To provide these heating function, the engine is run when it is not providing motive power, and the line on the MFD is blank.

I can feel engine vibration in the wheel when stopped as my que to when this is happening. In weather around freezing, I will turn off the Climate Control system then, and back on when running down the road.

 

I noticed this too. There are plenty of situations where it will be running, but not moving the car or charging the hybrid battery.

Heating the catalytic converter does indeed reduce pollution, at least of the NOx and SOx variety. This is probably the reason for Stage 1 and 2 operation. Below 104 F (I think), the combustion efficiency is bad enough that Toyota probably made a determination that it should be the minimum cutoff. Since there are no CO2 mandates yet in the States, it's a tradeoff to achieve the higher EPA and California classifications which are based on non-CO2 pollution.

I have started doing this too. Since I'm already wrapped up in sweater, coat, gloves, etc. to go outside, I just keep them on a bit longer until the car warms up on its own through driving.

I have also noticed that, when the car does run the ICE to keep itself warm, it does try to make some use of that energy by charging the battery. However, it won't do that if it's already at 7 bars or 8. So, for this, I try to drain the hybrid battery down to 4-6 bars when I park at night. If I get off the main roads with 6-8 bars, I try to drive the last half mile or mile with the heat off and in stealth mode, knowing it will need to run to warm up in the morning. If you drop it below 4 bars, the ICE will run without the 10 second delay and will run to recharge up to about 6 bars, even if it is already warm from an EBH. Because you lose a lot from charge/discharge inefficiency, and because the car won't let the ICE charge the battery beyond 7 bars, it's a tradeoff.

 

This is one of the things I like best about my new ScanGauge. In order of invaluableness (is that a word?)

1) I keep the engine rpm on the upper-left number. If the engine is not running it is 0.

2) The coolant temperature.

3) You can program in the traction battery state of charge, you get a more accurately displayed reading than the mfd bargraph.

4) The 12v battery voltage. If your 12v battery is becoming weak, you see it and don't clog up PriusChat with zillions of questions about your car acting wierd!

Anybody can install it, you just plug one plug into the big plug at the bottom of the dash! IMHO, Toyota should display those 4 values on the mfd, some not necessarily on the main screen.