MPG meter

Post Mon Jul 18, 2005 10:21 pm

what controls the MPG meter? mine works, but then again it doesn't...
when i start the engine the needle moves from one side to the other, and then it stays there so it's not broken. On the motorway it moves all of 3mm. It would be nice to know if i can fix it at all

Post Mon Jul 18, 2005 11:13 pm

Think that means it's not getting any speed information.
Came across one like this once that I tried to fix. Found a burnt out resistor in the path between the speedo and ecometer circuitry on the SI board.
Replaced resistor, didn't burn, but meter didn't work either.
Gave up at that point.
Try to source a fresh instrument cluster and try that.

Post Mon Jul 18, 2005 11:36 pm

ah, is the SI board involved it the whole thing? mine doesn't work, i think the rechargable battery is worn or something... a very high resistance in the circuit would makes sense i suppose, since it does move a bit, but onlty really noticable above 80mph...

cheers brian

Post Mon Jul 25, 2005 12:24 pm

Most likely flat SI-board batteries.. Next up is that your tach will start moving jerky.

- Rick

Post Mon Jul 25, 2005 2:10 pm

The one I'm refering to still didn't work with a fresh SI board.

Post Mon Jul 25, 2005 4:36 pm

The fuel consumption is calculated from the flow of fuel at the injector and the speed of the car. When it was launched in the 80's BMW claimed that it was the only accurate one on the market and that all the others gave was an indication of fuel consumption.

Post Mon Jul 25, 2005 4:42 pm

moving on from the subject at hand and apologies for hijacking the thread but......

Has anyone ever had anything to do with the electronic display on an E34 5 series?

My old man is trying to solve a silly intermittent fault which effects the digital display on the dash. This 5 series has the elctronic odometer and display telling you low oil, fasten belt etc.

Briefly it sometimes refuses to light up at all when the ignition is switched on. Then a few seconds later if you turn it off and try again it works.

When you press the brake pedal the temp gauge on the right moves a little.

If the display doesn't work, next time it comes on it will have zero'd the mileage on the trip display, but it does retain the total mileage on the odometer. It is also saying low oil and low coolant when in fact the levels are fine.

Anyone any ideas? And where is the silly little battery in the intrument unit.Had that out and coudn't see anything when we took the back off.

Post Mon Jul 25, 2005 8:47 pm

E30BeemerLad wrote:moving on from the subject at hand and apologies for hijacking the thread but......

Has anyone ever had anything to do with the electronic display on an E34 5 series?

My old man is trying to solve a silly intermittent fault which effects the digital display on the dash. This 5 series has the elctronic odometer and display telling you low oil, fasten belt etc.

Briefly it sometimes refuses to light up at all when the ignition is switched on. Then a few seconds later if you turn it off and try again it works.

When you press the brake pedal the temp gauge on the right moves a little.

If the display doesn't work, next time it comes on it will have zero'd the mileage on the trip display, but it does retain the total mileage on the odometer. It is also saying low oil and low coolant when in fact the levels are fine.

Anyone any ideas? And where is the silly little battery in the intrument unit.Had that out and coudn't see anything when we took the back off.

Possibly, indeed probably, talking complete rubbish, but isn't this a known fault, where one small capacitor fails?

Post Mon Jul 25, 2005 8:49 pm

Open to suggestions on this one really mate.

So do you know how best to going about getting this tested or is there an e34zone somewhere? :lol:

Post Mon Jul 25, 2005 8:51 pm

this site is fairly useful for e34 stuff,

www.bmwe34.net

Post Mon Jul 25, 2005 10:02 pm

cheers big fella

Post Mon Jul 25, 2005 11:07 pm

tusker wrote:The fuel consumption is calculated from the flow of fuel at the injector and the speed of the car. When it was launched in the 80's BMW claimed that it was the only accurate one on the market and that all the others gave was an indication of fuel consumption.

Mine works fine - but only when I switch off the CD player??

As soon as I turn on the tunes, the gauge drops to zero,
Any ideas?

Post Mon Aug 01, 2005 9:27 pm

my mpg stopped working a while ago changed my cluster and put in new batteries still not working were is the sender for the fuel flow i dont really mind it not working but it d be nice to watch how bad it is when its flat out

Post Mon Aug 01, 2005 9:39 pm

Thoughout the 2 years i've owned my e30 the mpg gauge works whenever it feels like it. Sometimes when you start up the car it works fine and other times it chooses not to work. Occassionly it stops working when driving along which causes the engine to cut out for a brief moment