2014 REx Fuel Tank coding...how do I know it worked?

[msnyderfoto]

As mentioned in another thread, my new to me 2014 REx was already showing the HSOC option and no option to expand the fuel tank...leaving me to believe that was already coded into the car. Is there some indicator as to whether this is the case or not? I was fooling around in some menus before buying the car, and somehow came across a fuel tank capacity level meter. I think it said the left tank was full, but the right tank was empty. That made me think that the car is not set up in euro tank specs, but the guess-o-meter tells me I have 91 gas range miles. Would love some clarification on this.

 

[msnyderfoto]

ANYONE?

 

[alohart]

As mentioned in another thread, my new to me 2014 REx was already showing the HSOC option and no option to expand the fuel tank...leaving me to believe that was already coded into the car. Is there some indicator as to whether this is the case or not? I was fooling around in some menus before buying the car, and somehow came across a fuel tank capacity level meter. I think it said the left tank was full, but the right tank was empty. That made me think that the car is not set up in euro tank specs, but the guess-o-meter tells me I have 91 gas range miles. Would love some clarification on this.

What you are describing is the hidden menu accessible on the i3 instrument panel which is apparently shared by several BMW models. The fuel tank menu items don't seem to apply to an i3. However, I've owned only BEV's, so maybe they're applicable to a REx.

It would be unusual for the previous owner to have enabled HSOC but without increasing the available fuel capacity. A 91 mile gasoline range seems higher than normal. It was supposed to be no greater than the electric range which was 72 miles as rated by the E.P.A.

You could run the REx engine until it runs out of fuel and then pay attention to how much fuel the tank will take until the fuel nozzle clicks off. Don't continue adding fuel after the nozzle clicks off because you could "overfill" the tank such that liquid gasoline enters the activated charcoal gasoline vapor trap which could cause problems. I don't recall the restricted North American fuel tank capacity (1.9 gal.?). It might be as high as 2.4 gal. after the software-limited fuel tank capacity has been increased.

Alternatively, you could license the BimmerCode app (<$50) which would show you the current the fuel tank capacity in liters and allow you to increase it if it's still software-limited. You'd also need to buy an OBD to either WiFi or Bluetooth adapter (~$30 at Amazon) to wirelessly connect your smartphone to the OBD port. BimmerCode can change the behavior of many features, so many including me find its purchase very worthwhile.

 

[TwoLiterSoda]

What you are describing is the hidden menu accessible on the i3 instrument panel which is apparently shared by several BMW models. The fuel tank menu items don't seem to apply to an i3. However, I've owned only BEV's, so maybe they're applicable to a REx.

It would be unusual for the previous owner to have enabled HSOC but without increasing the available fuel capacity. A 91 mile gasoline range seems higher than normal. It was supposed to be no greater than the electric range which was 72 miles as rated by the E.P.A.

You could run the REx engine until it runs out of fuel and then pay attention to how much fuel the tank will take until the fuel nozzle clicks off. Don't continue adding fuel after the nozzle clicks off because you could "overfill" the tank such that liquid gasoline enters the activated charcoal gasoline vapor trap which could cause problems. I don't recall the restricted North American fuel tank capacity (1.9 gal.?). It might be as high as 2.4 gal. after the software-limited fuel tank capacity has been increased.

Alternatively, you could license the BimmerCode app (<$50) which would show you the current the fuel tank capacity in liters and allow you to increase it if it's still software-limited. You'd also need to buy an OBD to either WiFi or Bluetooth adapter (~$30 at Amazon) to wirelessly connect your smartphone to the OBD port. BimmerCode can change the behavior of many features, so many including me find its purchase very worthwhile.

My 2016 gas ranges from 82-87 depending on which mode I’m in. Unrestricted tank.

To the OP, Alohart is spot on with how useful BimmerCode and odb2 devices are. Plenty of options that make it well worth the money.

 

[larrykalenda]

I recently filled up a tank I ran dry and it took 2.3+ gallons. I filled until it "clicked" and stopped. I do fill slow as it gets near the top.

 

[jfran2]

As I recall the process, when you code the car for HSOC, your fuel tank will change from using 1.9 gallons to 2.1. I believe there is a way to get into the advanced menu and increase it further to 2.4 gallons, but I haven't tried that in my 2015 REX.

John Francis
Rolla, MO

 

[ksnax]

2.1 gal should be the nominal capacity after coding. While an additional 0.3 gallons can be trickled in, it is technically overfilling it and can potentially spill over into the evaporative venting and foul the system.

 

[TheAirman]

From 2013 until the end of production, the i3 used the same tank. (part # 16117391827).

Here's a link to one:
https://www.ebay.com/itm/1449073516...lp:4429486&itmmeta=01HS4KY9W65GH5FQST8VDQB34M

The capacity was increased from 1.9 US gallons to 2.3 US gallons on the post LCI models the Range Extender Digital Engine Electronics (RDME) and also possibly the Hybrid pressure refueling electronic control unit (TFE) .

The tank level sensor is on the fuel pump itself. You overfill above that, you risk getting fuel in the vent line through the filler neck.

 

[ksnax]

From 2013 until the end of production, the i3 used the same tank. (part # 16117391827).

The capacity was increased from 1.9 US gallons to 2.3 US gallons on the post LCI models the Range Extender Digital Engine Electronics (RDME) and also possibly the Hybrid pressure refueling electronic control unit (TFE) .

The tank level sensor is on the fuel pump itself. You overfill above that, you risk getting fuel in the vent line through the filler neck.

Not to be contrarian, but I am not clear on your source for the 2.3 gal figure as I have only seen I01 info. This is from BMW's 2014 REx pub:



Don't use their liter reference, as it represents a rounding error for significant digits that is better calculated in gallons.

My interpretation of that is that the reserve is a physical limit at ".5 gallon". So that only leaves the question of how much of the fuel the pump can actually move out of the tank.

 

[robthebold]

Don't use their liter reference, as it represents a rounding error for significant digits that is better calculated in gallons.

While it's got more digits, I'm not sure that's the conclusion I'd draw.

 

[alohart]

While it's got more digits, I'm not sure that's the conclusion I'd draw.

I wouldn't draw the conclusion that the fuel capacity is better calculated in gallons, especially when liters would be the native units used by BMW. The conversion to gallons requires additional significant digits to express the volume of 9 liters to reduce the loss of accuracy. 2 liters is more accurately expressed as 0.52 rather than 0.5 gallons. The world be better with all countries using the metric system which would avoid needing all of these conversions.

 

[ksnax]

I wouldn't draw the conclusion that the fuel capacity is better calculated in gallons, especially when liters would be the native units used by BMW. The conversion to gallons requires additional significant digits to express the volume of 9 liters to reduce the loss of accuracy. 2 liters is more accurately expressed as 0.52 rather than 0.5 gallons. The world be better with all countries using the metric system which would avoid needing all of these conversions.

Fair point, but that would buck scientific and engineering convention on the handling of significant digits. They cited a greater degree of resolution in gallons with the rounding error in the hundredths. If they were simply running it through a converter, it should only cite tenths.

 

[robthebold]

Fair point, but that would buck scientific and engineering convention on the handling of significant digits. They cited a greater degree of resolution in gallons with the rounding error in the hundredths. If they were simply running it through a converter, it should only cite tenths.

Unless that engineering degree came in a box of Cracker Jacks, the greater degree of resolution was just the translator not knowing how sig figs worked . . . They saw 9 liters and assumed that meant 9.00 (repeating on to infinity) liters, which of course it did not. Then they naively divided 9.00 by 3.78 and got 2.38. Just dividing a number with one sig fig by a conversion factor with 3 sig figs doesn't magically increase the precision . . .

. . . unless of course you figured the BMW engineers were working in the US customary system and only converted it to metric for benefit of German management . . .

I should probably add . . . no unit converter is gonna preserve your significant digits for you. That's all on you. You are the unit converter, and you have to know how "scientific and engineering convention" works.

 

[cpallenjr]

As mentioned in another thread, my new to me 2014 REx was already showing the HSOC option and no option to expand the fuel tank...leaving me to believe that was already coded into the car. Is there some indicator as to whether this is the case or not? I was fooling around in some menus before buying the car, and somehow came across a fuel tank capacity level meter. I think it said the left tank was full, but the right tank was empty. That made me think that the car is not set up in euro tank specs, but the guess-o-meter tells me I have 91 gas range miles. Would love some clarification on this.

I can’t provide a credible reference right now but I believe that cars with the 94 ah batteries were coded to use the full capacity of the fuel tank from the factory. My 2017 94 ah Rex fuel range estimate runs in the neighborhood of 88 miles when full and with the car in Eco Pro. I then used Bimmercode to enable HSOC amongst a few other things.

 

[ksnax]

Unless that engineering degree came in a box of Cracker Jacks, the greater degree of resolution was just the translator not knowing how sig figs worked . . . They saw 9 liters and assumed that meant 9.00 (repeating on to infinity) liters, which of course it did not. Then they naively divided 9.00 by 3.78 and got 2.38. Just dividing a number with one sig fig by a conversion factor with 3 sig figs doesn't magically increase the precision . . .

. . . unless of course you figured the BMW engineers were working in the US customary system and only converted it to metric for benefit of German management . . .

I should probably add . . . no unit converter is gonna preserve your significant digits for you. That's all on you. You are the unit converter, and you have to know how "scientific and engineering convention" works.

Or perhaps they didn't convert anything but actually measured it. The point is that their published figures provide higher precision for gallons, extending it to two decimal places vs. whole numbers for liters. Did BMW lie or is their metric rounded? Only way to really know is to measure it directly I suppose.

 

[robthebold]

Or perhaps they didn't convert anything but actually measured it.

Sure they did . . .

 

[ksnax]

Sure they did . . .

Yeah, that is actually possible due to needing to meet California's standards for the car at the time. Until somebody actually measures this however, it's a pointless discussion beyond knowing that overfilling compromises the EVAP canister.

 

[Tacfoto]

My car is a 2017 with eh 94ah battery so it's already at the higher fuel tank capacity. I regularly run it "dry" and the pump usually clicks off at 2.0-2.2 gallons when filling. I give it one more click... My range prediction on gas with a full tank varies from 75-95 miles with the usual i3 optimism, occasionally 100. I seem to get 70-80 miles of actual range out of it when used on a long trip.

If your fill-ups are 2+ gallons, then I think you have the full "coded" capacity.