Hello and happy 4th of July everyone!

Here it goes, today I fill my tank and before I reset the trip gauge I noticed that the computer (estimated) showed I could go 369 miles on that tank of gas. So I drive less than 2 miles and now my gas gauge suddenly drops to half a tank, I noticed that the new recalculated estimate of 369 miles had dropped to 292 miles. If that's not strange enough as I'm driving (remember this happens within 2 miles after gas up) my estimated mileage is 290 miles starts climbing back up to 369 mile till fill up.

If that's not enough when all this is going on I notice that my gas gauge bars get super bright, then appear to dim down, I thought my gas bars were going to explode there so bright!! To make matters worse when I put the UFO style key into the area where it slides in, a couple of times when I go to press "Start" button the dash goes dark until I reinsert the key again then it starts right up.

Just to clear things up, there's nothing wrong with my battery. I haven't been using the physical UFO type remote key into the docking module next to the start button, instead I keep key in pocket and start the car remotely. Since I have been doing that I have had NO startup problems

What's going on here?

YouTube video, second video skip to time index 50 seconds.

Video 2

 

I have been search everywhere and may have found a cause for the brightly lit gas indicator, tell me what you think.

First after 95 miles I decided to fill my tank back up today and my gas light has returned to normal. Could a faulty sending unit cause the lights to glow brightly to get my attention that I'm very low on gas?

 

Can you share what you were doing, how you were driving just prior to filling up?

On the DTE, the calculation increasing is not unusual. The computer bases that on your most recent mileage and what it detects as the level of fuel remaining in the tank. If I've just come off the track or a particularly spirited run, my MINI may think I can go less than 300 miles even on a full tank. But driving it "normal" will cause the computer to eventually recalculate to something more in line with what I know the normal mpg to be. If I'm driving in the right direction and taking it easy on the BRP, I've been able to get the combination of DTE and actual miles driven up to over 600.

I've also noticed the improving range is pretty consistent during daily driving right after I fill up. I suspect that is due to the computer becoming more conservative as I get closer to empty and it continues to use that value for a little while after a fill up. Typically when I fill up the computer initially reports a range of between 430 and 460 depending on how I've been driving. Usually by the end of my commute to work, I've driven the range up to over 500 (or DTE + actual miles driven is greater than 500).

In your second video, I cannot tell whether the gauge is getting brighter due to dim light conditions and the light on your camera is causing it to then dim. I've never heard of the gauge getting brighter as your gas level gets lower and haven't noticed that in mine. I wouldn't really make sense given your gauge is showing you close to full.

 

I see that my gauges change intensity based on ambient light around them.. or at least it seems that way. Its annoying, but I've grown to accept it.

As for the fuel gauge calculation, its based off of fuel volume and average consumption rates. Drive like a granny and "grow" gas in the tank,... drive like a demon and watch it drop like at rock... granny mode... "grow more" gas...

 

I think I remember my Owner's Manual stating that the DTE works off of the MPG used over the last 30 miles.

My car's fuel level got very confused when my car was towed on a flat-bed. I think it may have been due to the flatbed tilting the nose of the car up in the air for loading and unloading. The gauge went from three carrots to one, and said I had six miles of range left when I re-started it. I quickly shut it down (to look for fuel leaks), and when I re-started it showed two red carrots and 30 or so DTE.

I filled up about 3 miles after that, and only got ~10.3 gallons in, out of a capacity of over 14 gallons. (I've put 14 in a couple of times before.) So the gauge was considerably off.

 

With the estimated gas mileage aside, the fact that the tank is full and the computer thinks it's half empty that indicates something is wrong! The camera has nothing to do with what you saw the gas meter showed, the gas gauge glowed extremely bright off camera. What you saw on the video did happen. I don't know what to other than my driving habits have been consistent for days.

 

My miles to empty drops like a rock the closer I get to empty. The last 50 (did this once), I dropped from 47 to 20 on a 6 mile drive home on side streets taking it easy. Since then, I refill as soon as it hits 2 lights.

 

The minis fuel tank is a "saddle" type tank, with two sides. There is a fuel level sensor on a float on each side.

The reading on your fuel guage is a combined reading from the two senders. It is not an instantaneous reading, otherwise it would fluctuate widely when you went around a corner and fuel sloshed around. Rather it is average buffered reading from the recent past.

Probably what is happening in your car is one of the sensors is faulty, either the float is stuck, or sending an innacurate reading. Sometimes this can be a transient thing that fixes itself, sometimes it is a more recurrent thing.

If you want to have a closer look, if you know how to access the secret OBD menu on the dash, menu 6 gives you fuel level readings. There are 3 readings, 6.0, 6.1, 6.2. I can't remember what order they are in, but one gives you instantaneous readings from the left and right in litres, one gives you the averaged buffered reading in litres (ie what is displayed on your fuel guage) and one gives you the voltage each gauge is sending. If you look at this and one side is much higher than the other, then this means either the sensor is faulty or the pump that sends from side to side is faulty.

I can't explain the bright fuel guauge. However, if you access the secret OBD menu number 2 this goes through a test routine of every light and dial in the instrument console to check they are working properly.

Robbo

 

Why do you say the computer thinks you are only half full? In both videos, unless I missed something, your fuel gauge shows only one light not lit. For my MINI, that would typically correspond to 2-3 gallons.

How many gallons did you put in when you filled up? Are you sure it was topped off?

On the other odd startup issues, you state you know your battery is good. Can you share how you verified that?

 

http://www.realoem.com/bmw/partgrp.d...26&hg=16&fg=05

 

Wait, are you talking about how the carrots turn red when low on fuel?

 

Yes I'm talking about the carrots except they do not turn red they glow extremely bright, then dim down. As of yesterday they were glowing extremely bright then dim again every few seconds, it's beginning to happen more often which is good because I can now have Mini actually see what going on. I'm beginning to think that it's just a bad pressure sensor or the sending unit in the tank causing the issue.

Does anyone know what components are responsible for calculating how many estimated miles to fill up? ECU or is it the sending unit itself?

Thanks

 

Um.. Does this happen while driving under trees or overpasses? The dash will adjust brightness based on ambient light.

My carrots change brightness under every overpass or long tree grove.

It has nothing to do with a pressure sensor in the tank (which, while there is one, it has nothing to do with the fuel level circuit..)

 

I drove down a level street in constant brightness with no changes in lighting, it changes quickly and not gradually. If it's not the fuel level circuit why would it first show a full tank of gas at fill up and a mile later show half a tank the slowly rise from half a tank to a full tank? That to me sound like a meter conflict = fuel level circuit. My metering carrots never behaved like this for the first two months of owning the car.

 

Ok, well.. Sounds to me like its more an issue with the gauge/electronics that monitors fuel slosh and ambient light. This makes more sense since the brightness has nothing to do with fuel level...

Never know, could be something as simple as a loose ground.

 

I just thought I would update everyone about my gas tank meter issue, the fault was a short in the resistance wire that goes to the console in the dash. As you know you can't have wires in the gas meter, they instead use a resistance based wire that would only act up when close to a full tank. So by replacing the gas meter fix the problem.

Just thought I would add to the resources of this great forum so other's can come here to find answers for similar issues with you gas tank meter.

Thanks,
Systemlord.