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Discussion Starter #1
Up until recently I've been getting between 23 and 28 MPG, which is pretty reasonable and expected. Trouble is, just the other day I had to call a breakdown service to replace my old worn out battery, and since then I've been dismayed to see my MPG drop to around 12 MPG even though I'm driving the same as normal. Not only that, but when I filled up for the first time since having the battery changed it was reading far more in the tank than I was expecting. The fact that the readings have been odd ever since the battery change seems too much of a coincidence. Could the change have knocked all the computers out of sync or something?
 

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Discussion Starter #3
Thanks for the info. Yeah, it looks like that's what's happened. What's this procedure they mentioned for getting the system working properly again, or is it just a case of driving the car until it relearns everything?
 

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When you disconnect the battery, the KAM is reset (Keep Alive Memory). Think of it like rebooting a PC, and all the RAM is refreshed when you log back in.

The ST should actually have more pep, because the ECU is relearning your driving habits and will eventually adjust fuel ratios as needed. If you train it to be more conservative, it will eventually regain your MPG as you expect.
 

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Discussion Starter #5
When you disconnect the battery, the KAM is reset (Keep Alive Memory). Think of it like rebooting a PC, and all the RAM is refreshed when you log back in.

The ST should actually have more pep, because the ECU is relearning your driving habits and will eventually adjust fuel ratios as needed. If you train it to be more conservative, it will eventually regain your MPG as you expect.
You mean all this time I've been getting what the original owner taught it?
 

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You mean all this time I've been getting what the original owner taught it?
It continues to learn based on your driving habits, but yes - it would have never had a reset unless you had pulled battery/disconnected battery before, or reset KAM with an accessport.
 

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Up until recently I've been getting between 23 and 28 MPG, which is pretty reasonable and expected. Trouble is, just the other day I had to call a breakdown service to replace my old worn out battery, and since then I've been dismayed to see my MPG drop to around 12 MPG even though I'm driving the same as normal. Not only that, but when I filled up for the first time since having the battery changed it was reading far more in the tank than I was expecting. The fact that the readings have been odd ever since the battery change seems too much of a coincidence. Could the change have knocked all the computers out of sync or something?
Is that mpg drop calculated by you based on miles and how much fuel you put in the car or by the car's calculation? 12mpg actual is really low, like impressive to get that low if nothing is wrong with the car.
 

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Is that mpg drop calculated by you based on miles and how much fuel you put in the car or by the car's calculation? 12mpg actual is really low, like impressive to get that low if nothing is wrong with the car.
I calculate it based on what actual mileage I've done on the journey compared to the amount of miles till fill up. At the moment it's dropping like a rock, but then again it was showing many more miles when I filled up than I put in the tank, like around 200 miles more than I expected. Mpg wise it seems to be back to normal now, because the readout said just over 25mpg today when I checked it, and that's after I was caught in traffic.
 

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I calculate it based on what actual mileage I've done on the journey compared to the amount of miles till fill up. At the moment it's dropping like a rock......
The Acar app is your friend. it does all the hard work for you. you input odometer, gallons, and price if you feel like it.
I don't work for them, but it integrates with fuelly (in my sig) and gives graphs and lets you add notes so you can track your progress. way easier than doing it manually. Just my .02
The car's computer tends to be off.
 

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The Acar app is your friend. it does all the hard work for you. you input odometer, gallons, and price if you feel like it.
I don't work for them, but it integrates with fuelly (in my sig) and gives graphs and lets you add notes so you can track your progress. way easier than doing it manually. Just my .02
The car's computer tends to be off.
Agreed with all above. The car's mpg estimate I've had to show anywhere from 1/2 mpg low to around 4 mpg high (such as my last fill-up). Kinda annoying when it says you got 35.6 mpg and you really only got 31.7.

The Fuelly app (aCar thing) is really handy, though, for more than just fuel stuff... You can put in reminders for oil changes, tire rotations, put in notes about any mods so you can see any effect on fuel mileage, etc.
 
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