OBC fuel reading

Thu Dec 22, 2005 6:22 pm

Anyone whos got a OBC fitted:

can you tell me what reading you have on fuel remaining when yer fuel light comes on... ive never seen my fuel light on yet,bulbs been checked yet ive got 43 miles left on the OBC but no illuminated fuel bulb as of yet..

each will be slightly different i know but wanna make sure nothing is wrong here.

cheers

Thu Dec 22, 2005 6:31 pm

The fuel light's likely to be more accurate then the OBC tbh... once you know how much is in the tank, you can calibrate the OBC to give you a good idea though

I think I've got mine fairly accurate now - my light comes on with about 12 / 15L still in the tank I think, so that's what my OBC says too...

Why don't you brim it from where it is now & see how much there was left?

Guest · Sat Dec 24, 2005 3:53 pm

I had this. My bulb had blown. It now lights with 6 or 7 litres showing on the OBC. The needle looks like its reading empty well before the light appears....

Wed Oct 25, 2006 11:21 am

once you know how much is in the tank, you can calibrate the OBC to give you a good idea though

what are the steps to perform an OBC calibration?
a previous thread mentioned using small screw behind the tiny plastic cap on the lower left of the panel, but no detail though.

Wed Oct 25, 2006 6:03 pm

I think I have seen OBC Calibration on the Zone a little while back.

My light comes on when the OBC is down to about 15km left, as bmw325virgin says the needle is right at the bottom before the light comes on.

If you've retrofitted the OBC you need to make sure you have the right code plug in the back for the tank capacity that you have I believe.

Thu Oct 26, 2006 3:06 pm

my fuel light comes on when I have 3 - 4 liters left.....

Sat Oct 28, 2006 9:17 pm

If you've retrofitted the OBC you need to make sure you have the right code plug in the back for the tank capacity that you have I believe

Where can we get a list of which code plug works correctly with which e30 model?

Also about the OBC calibration, how d'ya properly remove the plug without destroying it.

Sat Oct 28, 2006 9:39 pm

mark_i wrote:
If you've retrofitted the OBC you need to make sure you have the right code plug in the back for the tank capacity that you have I believe
Where can we get a list of which code plug works correctly with which e30 model?

Also about the OBC calibration, how d'ya properly remove the plug without destroying it.

http://mysite.wanadoo-members.co.uk/smi ... RATION.htm

Sat Oct 28, 2006 10:12 pm

According to the owners manual my 89 320i has 6 litres remaining in reserve when the light comes on. (63ltr tank.)

Sun Oct 29, 2006 12:07 am

Thanks for the table smithy318i. I came across it later after posting the rquest while researching an OBC retrofit. Mark

Mon Feb 25, 2008 7:03 pm

My OBC shows 35 miles left under the 'range function when my fuel light comes on.

I have the correct coding plugs as I ordered a new one for the OBC to match my clock/engine/model.

How do I calibrate the range reading as the calibration pin seems to allow adjustment for all other functions except this one?

Mon Feb 25, 2008 11:17 pm

Cha_Maan wrote:My OBC shows 35 miles left under the 'range function when my fuel light comes on.

I have the correct coding plugs as I ordered a new one for the OBC to match my clock/engine/model.

How do I calibrate the range reading as the calibration pin seems to allow adjustment for all other functions except this one?

This has been translated from German so might be a little difficult to read.

If the OBC is retrofitted or if the fuel tank sender is changed, you will need to calibrate the OBC again in order to receive a more precise indication of range. Some OBCs do not have any adjustment possibilities, this mostly apply to the US models. A few prefaces for range computation in the BC: Over pin the BC gets 13 and 18 the measured value of the immersion tube giver and the contact of the reserve light. As long as the reserve light out is, the range from the level of the tank and the average consumption of the last approx. 30km is computed. If the reserve light turns on, the BC takes the conditions stored in the coding plug (e.g. with the E30 5L) in place of the true level. The odometer reading is down-counted only, a clamping of the battery e.g. leads to still wronger prognoses of the range. Therefore the conclusion results that when lighting up the reserve light also the BC on 5L remainder contents in the tank must be adjusted exactly. (E24 4.5 or 5,5L, E23 8L, E28 5,5L) Now to the act: The tank should be relatively empty. Now one can drive until the reserve light straight turns on or pulls the immersion tube giver slowly so far out of the tank, until it lights up. I have myself for the 2. Solution decided, since I did not have desire to screw in the middle on the highway at the car. Rear seat remove, felt over on the front seat passenger side turn. With screwdriver maintenance covers unscrew, when removing on seal respect. Remove the cover for the potentiometer with a pin at the BC. Ignition on - position 2, all power consumers (e.g.: Back window, exhaust, climate etc.) out. At the BC the keys and press at the same time, in order to indicate the level of fuel in the tank. The following work is shown at the before Face elevator model, since after Face elevator has the model the fuel pump in the tank, can some details differently look. Immersion tube givers solve (SW8) and slowly raise, until the reserve light straight turns on evenly in such a way. Since the immersion tube giver only a tiny Einfuelloch possesses for the better absorption, one should bring along something patience. Immersion tube givers in this position wedge (here with the red screwdriver). In such a way adjust the potentiometer at the BC with a Uhrmacherschraubendreher to the transition of 6 to 5L that the announcement stops however at the end on 5L. (E23, E24, E28 appropriate values) Everything again in reverse order assemble and completely.

Mon Feb 25, 2008 11:38 pm

Mine goes to a min of 15 litres I think, even with the screw turned completely.

Will not go any lower even if ou run out of fuel. I have correct coding plugs and to be honest the range and MPG, etc is way out.

Mon Feb 25, 2008 11:51 pm

Smithy318i that is barely decipherable.

Mon Feb 25, 2008 11:52 pm

I saved picture as and then you can zoom in

Tue Feb 26, 2008 4:18 pm

slightly off thread but how do i stop my fuel gauge reading irregularly, i could fill it full use it to 3/4, then the next time i use it and start it up it will read only half a tank (for example) and take a while for the true reading to come thru..... i wonder if this will affect the readings if i fit an obc.... so i dont thread hi-jack, can people pm me their ideas or tell me if their gauge does this

Thu Mar 06, 2008 3:12 pm

Cha_Maan wrote:Smithy318i that is barely decipherable.

makes perfect sence to me.

http://mysite.wanadoo-members.co.uk/smi ... RATION.htm

Thu Mar 06, 2008 3:44 pm

My light comes on when the obc says 20miles ish then the obc goes up to about 35miles. I didn't know if my light worked for about a year so I just kept driving till it came on and after 9miles left it will show _ _ _ _

Thu Mar 06, 2008 11:30 pm

My light comes on when the OBC says 120 odd miles. But then I've not calibrated it. The light is far more accurate than either the obc or the fuel level meter.

Sat Mar 08, 2008 1:48 pm

In the light we trust. My OBC sticks at (Range: 19 miles) for about five miles of driving, then jumps upto (Range: 21 miles) for a while before erratically counting down and then flashing - - - - at me for about another 5 miles... then runs out of fuel....

(yes i have run it out of fuel, but the day after i replaced the fuel tank so i knew there was no crap in it to get stuck in the injectors....