Fuel tank range reads +300

[bimmer630]

I just swapped in an OBC.
I filled my fuel tank today and the display reads +329. also before I filled it, I was almost on empty and the range was around 31, and INCREASED to 35 as I drove!!

In my owners book it states that any number shown in the OBC range display with a + in front of it, indicates the tank is overfilled by that much. Im not super picky but id like to get this OBC to work at least a little bit accurately.
The obc came out of i think an 87 325i, according to the coding plug in the back of it. a chart i found online shows a different coding plug after 87.

If I get the correct coding plug will my range function work correctly?

[Dermeister3]

I got that too usually.

the +329 means you can go over 329 miles/kilometers on the current tank of gas.
Also, the range can go up from driving slowly and conservatively. The range is recalculated often so it'll fluctuate from your current driving habits.

[long tall eta]

your obc is fine. if u fill the tank and u get a +, u have the stated miles left to go plus. if u drive at highway speeds economically this number will be maximused or conversly, if ur beeting the shit out of it light to light the number will be greatly reduced even though the same amount of gas is in the tank. thats why they call it a computer. the same goes for the mpg function. the harder u drive, the less mpg she will read.

[nando]

the range is calculated off your instantaneous MPG, not the long term average. so it can go up/down considerably, and often.

also, 300+ miles is pretty realistic for a stock, well maintained E30.

the reason it went up after you filled is because the level sensors weren't done filling with fuel. they don't work instantly.

[Wh33lhop]

the range is calculated off your instantaneous MPG, not the long term average. so it can go up/down considerably, and often.

Really? That's pretty dumb.

Wish my OBC worked better with the m50. It was fun to play with. (if you are wondering, it works fine but the fuel mileage reading is inaccurate by 40% or so)

[bimmer630]

Something isn't right though. I was on e with the reserve light on and it said 40 miles left

[freeride53]

My obc said it had 27 miles left and it left me stranded in the middle of an underwater tunnel...day before I left for college :up:

[nomansland92]

My odc says over 400 when i fill it and i only get like 250 miles and it's set in miles per gallon

[McGyver]

yeah, they never got 0 miles. thats why you should put a can of fuel in the trunk and drive will you run out of gas so you know where the needle/OBC stops when you have absolutely nothing left. or just fill it up when you get to 1/4 of a tank to keep your pump cool.

[gath]

Mine shows 425+ and the light comes on whenever I get to around 36m left, one day I drove it till it showed 6m lefts and then showed -----, but I was able to get to the gas station without a hitch. It's a 325i and the highest I get is 360 miles on 1 tank.

[nando]

Something isn't right though. I was on e with the reserve light on and it said 40 miles left

the reserve (when the light comes on) is almost 2 gallons.

thus the "R" instead of an "E" on the fuel gauge..

[nando]

My odc says over 400 when i fill it and i only get like 250 miles and it's set in miles per gallon

you'd have to run the tank dry to know for sure if it was off.

also - if you've swapped motors or injectors, all bets are off..

[beybedba]

it's fine ...

[5Toes]

What does the reserve light look like when it comes on? I gotta pull my cluster this weekend and fix my gas guage, My pump likely hates me: I have been driving everywhere with just $20 in the tank. FML

[ohthejosh]

mine said the same when i filled up before drive from SF to LA. on the eta itll say +329 for a LOOOOOOOOOONG TIME :)