No "9999 mpg" on ScanGauge coasting engine off (EOC). UPDATE: fixed; free SG re-flash

[MetroMPG]

UPDATE: a fix for this issue is now available. You can mail in your gauge to have it re-flashed with the new code. Read on, or jump to post #32 for details.

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I plugged a ScanGauge (SG1) into my dad's 2006 Corolla automatic today, and noticed it does not read "9999" in the instant MPG when coasting up to a stop with the transmission in neutral and the engine off.

The engine was killed with the key, then switched back to "on" again.

The SG1 is set to "hybrid" fuel type to ensure it stays awake.

Instead of 9999, it showed me these instant figures (MPG US) at these speeds (km/h):

km/h    MPG(US)
55    340
52    320
50    300
45    270
40    240
35    210
30    170
25    160

Note: remember, these figures are shown with the engine OFF. I didn't check, but I suspect these would be numbers I'd see if I were coasting while idling.

Has anyone else seen this? I Googled but didn't turn up this specific issue with this car.

I haven't tried it with my SG2 because it's in my car at the Halifax airport.

The problem here is that the SG1 would be under-reporting trip/today/tank MPG if any engine off coasting is done.

[cfg83]

MetroMPG -

My EOC-MPG in my SW2 is always egg-zactly 10 times the MPH. But I am circa-1999 "GM" ECU/PCM, not Toyota 2006.

I think blackjackel will be able to comment on this because he has a 2005 Corolla LE. But I also know he was out of town for awhile, so he may not be able to comment until he gets back.

EDIT: Wait a minute, I didn't notice KM/h. Gotta do some calcs ...

CarloSW2

[cfg83]

MetroMPG -

Important Note: I use an SG1.

I went here :

How do you convert kmh to mph? - Yahoo! Answers

And got these conversion factors :

MPH = kph * 0.6215
kph = MPH * 1.60934

KM/H	MPH	MPG
55   	34.18	340   
52   	32.32	320   
50   	31.08	300   
45   	27.97	270   
40   	24.86	240   
35   	21.75	210   
30   	18.65	170   
25   	15.54	160

From the above, the algorithm looks *very* similar to mine, aka 10 times the MPH.

To me this implies, lacking the needed inputs for calculating MPG, the SG1 "defaults" to a failsafe MPG algorithm.

CarloSW2

[cfg83]

MetroMPG -

Question: When you EOC in the Corolla, what does the RPM parameter report? My SW2 reports 61 RPM, even though the engine is off. I think this is what the Saturn ECU/PCM reports.

CarloSW2

[groar]

If MPG = 10 MPH then GPH = 0.1.

It seams to me a possibility that the ECU signal can't send a lowest value for GPH.

My lowest consumption in my scenic at a steady speed is 2.3L/100 at 70km/h, ie a 1.61L/h = 0.425GPH.
Since last oil change, my consumption while coasting in neutral at idle at 60km/h is 1.2L/100 ie a 0.72L/h = 0.19GPH.

The 61 could also be the lowest value for RPM.

Time to define an OBD3 ?

Denis.

[cfg83]

groar -

Originally Posted by groar

If MPG = 10 MPH then GPH = 0.1.

It seams to me a possibility that the ECU signal can't send a lowest value for GPH.

My lowest consumption in my scenic at a steady speed is 2.3L/100 at 70km/h, ie a 1.61L/h = 0.425GPH.
Since last oil change, my consumption while coasting in neutral at idle at 60km/h is 1.2L/100 ie a 0.72L/h = 0.19GPH.

The 61 could also be the lowest value for RPM.

Time to define an OBD3 ?

Denis.

I think GPH is a value computed by the SG1. I do not think it originates from the ECU/PCM of the car.

I have seen 9999 MPG in a diesel Renault Megane sedan when I am in gear and I take my foot off the accelerator (in Brussels on business with my handy SG1).

My thinking is that the "61" is the "lower end noise" of the sensor in my car.

CarloSW2

[dcb]

The .1 gpm is coming from the ECU, not the scangauge. There are plenty of cars that can coast @ 9999 IIRC. Is there anything in xgauge or other newer functionality that can allow you to add some custom display logic (i.e. if rpm < 100 then mympg=9999)?

[Daox]

My Matrix does the same thing. It will go to 9999 in deceleration fuel cutoff, but with the engine actually off it shows a very small fuel usage.

[metroschultz]

My wifes Avalon works like Daox' Matrix.
9999 in DFC mode, but rolling (albeit high) mileage with EOC.
I am sure it is something in the software from Toyota.
S.

[MetroMPG]

Originally Posted by metroschultz

My wifes Avalon works like Daox' Matrix.
9999 in DFC mode, but rolling (albeit high) mileage with EOC.

I checked, and it's not even doing 9999 in DFCO. It showed between .2 - .5 gph, and seemed to change relative to engine RPM.

But it was reporting OPEN LP in DFCO and switching back over to CLSD LP when the RPM dropped low enough for fuel injection to resume.

Originally Posted by cfg83

Question: When you EOC in the Corolla, what does the RPM parameter report?

When I key off, it freezes at whatever RPM the engine was at, but drops to zero when I immediately key back on.

Originally Posted by groar

If MPG = 10 MPH then GPH = 0.1.

You're right: it was reporting 0.1 gph with the engine off and the key on.

Originally Posted by dcb

Is there anything in xgauge or other newer functionality that can allow you to add some custom display logic (i.e. if rpm < 100 then mympg=9999)?

Not sure - but this is a SG1.

I'm pretty sure Daox is using a SG2 though (no xgauge / add-a-gauge feature).

I do wonder if this has anything to do with the way the engine is stopped, ie. if it were a kill switch, would it handle it differently? Not really a big concern, since I don't drive this car often. But for others who do...