:: Fuel economy gauge...

[Ferret]

My TDs started doing this a while back, and then I noticed a pattern forming...

It would get a lot worse when the weather was cold and the cluster was a bit frozen. Took the guage apart and the pivot point/actuator on the guage was shot.

If you think about it, this isnt surprising as the iMPG guage does an order of magnitude more work than any of the other guages - it's constantly on the move all over the place despite the fact your speed and rpm arent changing that much.

I agree with Morgenster above - I think your mpg is calculated by the ECU - if it was based off the fuel tank sensor and speed sensor only you'd get some weird readings every time you hit a bump and the fuel sloshed around in the tank. The fuel sensor is just not accurate enough to pull these readings off. Also there's nothing in the fuel lines that can measure flow; so it's almost a dead cert that it's the ECU doing the math.

If your guage is doing weird things, suspect the cluster and/or physical guage - they're the most likely culprits. If your ECU was at fault I'd be expecting to see the engine not running properly... (though its output driver may have failed - which is very unlikely considering how hardened bosch electronics tend to be.)

[Ross]

HMMM, sounds plausible.
Qube does your "spare clusterboard" include the gauge? I've an earlt cluster I bought for the LCD display which I can't use anyway. It was from a member here, I can't remember who, who was having trouble with his caps. It has new cap I"m told but he was still having some probs, I don't remember what though.
Anyway if you need a cluster or the gauge let me know.