Outta Gas Range Calculation?

2875 Views 7 Replies 7 Participants Last post by MrPrescott, Feb 6, 2002

MrPrescott

Discussion Starter · Feb 5, 2002

For the first 4000 miles, I found that the low gas light always went on with almost exactly 3 gallons left in the tank. Also, the 'Range' was almost dead on given the both the average MPG and my calculated MPG.

Now, with 5500 miles, I notice that the range indicator seems out of whack, indicating I only had 8 miles to go when I still had well over 2 gallons left in the tank. What makes this more surprising is that I haven't been varying my driving conditions much, avoiding jackrabbit starts and pretty much staying around town (17 - 19 mpg). Not to mention that the average MPG indicated is right on my actual MPG.

Has anyone else seen their trip computer act this way?

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phillyflyer

· #2 · Feb 5, 2002

Mr. P.

I remember seeing your answer a while back on this forum. The trip computer is biased at minus 20 miles, so that when your trip computer reads 0, then you actually have about 20 miles left.

You can change the bias if you want, and you can find directions to do that here on the forum as well. Good luck, and don't feel bad. Your MDX is operating normally!!!

Ed

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davegood

· #3 · Feb 5, 2002

Here it is

I found out how to change the setting -- thanks to those that I stole this from...

Here's a copy for both Nav and nonNav calibrations from prior posts, just consolidated for future reference:

OK, here is what you can do. This applies only to the vehicles with Nav Systems.
Start the car and Press OK on the disclaimer screen. Press and hold the keys in this
order: Menu, Map/guide, and Cancel. Continue to hold all three for 5 seconds.

Press Trip Calibrate. You can now change the temperature reading offset and the
miles to empty offset. (An interesting note: Mine came with the miles to empty
offset set to -20 miles. Thus, it showed 0 when there was actually 20 miles or so
left. I suspect that Acura did this to insure that people do not run out of gas. I
changed mine.)

Tom

ardvarkus
Senior Member

Registered: Feb 2001
Location: Sierra Foothills near
Sacramento
Posts: 240
Tom- Good work.

It is NOT in the service manual.

here is how to calibrate a non-nav:

Non-Nav:

1. Turn on display

2. Press CLOCK plus RESET together for 5 seconds. It will enter a calibration mode

3. The value which will be changed will blink. First the temp offest will blink,
pressing TRIP will toggleto the Range Offset. Press TRIP again and you are out of
the calibration mode.

4. There are two values which can be adjusted: a RANGE Offset and a TEMP offset.
The MODE and A/C button will adjust down and up (- and +) respectively.

Like the NAV, the car comes with a -20 mile range offset. This is why when you fill
up you always have plenty of gas in the tank. It can be adjusted in 10 mile
increments.

For the temp offset, be careful. Static measurements can be affected by the
engine/radiator. Don't use the weatherman's temp. Be especially careful if you use
the temp to detect road icing. better to err on the low side.

Ard

PS Credit to Tom (mogur). Once you found the Nav's mode, it was logical that the
non-Nav would have one.

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Deposit - April 01 - held off for the '02 RedRock Pearl Touring / Nav -- build date of 12/15-12/19. Picked up car on 1/2/02 - happy new year!

Installed the Acura BSMs, wood shift knob, rear splash guards, Tailgate Deflector, and WT mats from Tim. at <a href="http://www.hondacuraworld.com">http://www.hondacuraworld.com</a>

Boards installed by the dealer. Also modified center console power to be always on.

10/03 Update -- traded the 2002 RedRock in for a 2003 Midnight Blue - Touring/Nav/Rear Ent. that I actually like much better than the 2002 - quieter, tighter, and a little quicker....

Already had both outlets converted to always on..

02/2007 update - just traded the 03 midnight blue MDX for a silver / black 2007 tech / RES. I really like it - going to add AW mats and tray and sport running boards.

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lester123

· #4 · Feb 5, 2002

Inaccurate gas range??????

I have a different concern with the gas range. I am not sure if it is working properly. Specifically, after I fill up the tank, I would expect the range to be about 350-375 miles, based on getting about 19-20 miles per gallon. It will show only about 200-220. When I said something to the service rep when I brought it in for an oil change, he indicated that he THOUGHT it worked that way, and was not accurate when filling it up.

What gives? My last car, it would go to the "real" remaining range.

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MDXMom

· #5 · Feb 5, 2002

I'm curious about this, too. After most fill-ups, I'm in the 260 - 280 range, which is fine, given a 20 mile lag. Once, though, the range was only 167 after a fill-up.

How is this calculation made? It seems unlikely that it could ever be absolutely correct given driving, temp, road, etc. variations... so I'm fine with using it as a guide, but I'd like to understand what's going into the equation, first order.

Thanks, anyone.

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TheWorm

· #6 · Feb 5, 2002

The range isn't calculated by your overall fuel economy nor by what the trip computer says you've been getting since the last fillup/reset: it figures it out based on your "most recent" driving. I don't know the mileage history it uses, but I'd guess something like your past 20 miles or so based on the change in numbers I've seen over the past year.

So, even if you typically get 20mpg and the trip computer shows that, if you're cross-towning it (e.g. stop and go at 15mpg) on the way to the gas station, the "range" after fillup is going to show something based more on your recent cross-town stop and go mileage rather than the overall. As you start driving again, the #s update up or down, depending on how you're driving right then.

Hope that makes sense.

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sspeedy7056

· #7 · Feb 5, 2002

DITTO WORM!

I have found WORM's explanation to be true in my case also. The owner's manual even describes this in it's definition of the Range reading, albeit, not in very good detail.

On one trip that was all highway from fill-up to fill-up, no stop-and-go at all, where I averaged 21.5 MPG, I saw over 300 as my range upon fill-up.

On another tank, where I drove all highway for 3/4 of the tank, but stop-and-go for the last 1/4, even though I averaged about 19-20 MPG, my Range at fill-up was reflected by the most recent stop-and-go, and displayed only about 250.

I have hit 0 on the range twice with about 1/8 to 1/4 of a tank to go. I'm going to do the recalibration from an above post and reset from -20 to 0.

REMEMBER: There is still a YELLOW light on the dash near the fuel guage with an icon of a gas pump signaling LOW FUEL, that lights up when you have about 1 or 2 Gallons left. I have determined that this is INDEPENDENT of the Range display on the Trip Computer or Nav display due to the fact when I did hit 0 in the past on the Range display, it still took a while for the Yellow light to come on (and I still only took about 16.5 Gallons of the 19.3 that the MDX holds.)

This makes me a little more comfortable in resetting the Range to empty display default to 0 from -20. It seems that the yellow light is the final warning that you are actually low on gas, since the computer is good, but never perfect!

Just my 2 cents.

Thanks to all the "Rocket Scientists" (and I sincerely mean that in a GOOD way) on this site for figuring out the "Calibration Mode".

Dave

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MrPrescott

Discussion Starter · #8 · Feb 6, 2002

Thanks for all the feedback all. I didn't know about the 'reserve'. But I'm wondering what mine is set for since I had about 50 miles left when it showed less than 10.

I'll check it out.

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