MPG gauge creeps upon braking

I apologize if this has been addressed already, but I didn't find anything useful through searching.

The car is a 2003 525i. Today I replaced all of the SAS vacuum hoses, as well as the vacuum hose from the F connector on the intake boot. It's nice not having the CE light on all the time, but now my MPG gauge is acting funny.

The needle reads normally while driving, but now whenever I start to brake before a stop sign/traffic light, it slowly goes down to around 15 and then comes back up when I come to a complete stop.

Is this normal behavior for the MPG gauge? I think it has something to do with the hose off of the intake. Where does that pipe end up?

You'll need to recheck your vacuum lines. You may have mixed up the lines. The MPG gauge is activated by engine vacuum, yes like old Dodges. You can trace it by following the line that comes from the firewall.

Good Luck.

Well, the SAS system functions correctly, and I double-checked the orientation of the check valve and the connections on the small electronic valve.

I wonder if one or both of the larger vacuum hoses on the sucking jet pump got dislodged or something. Would that cause a CE?

I believe your MPG gauge functions correct.
If it goes to the right when stepping on the brakes, and the speed is substantially reduced, the mpg gauge goes almost all the way to the right, and once stopped, it goes to "0" (all the way to the left)

Gotrice and Doru, thank you for the replies.

Interesting! All this time it never did that.

We have mpg gauges on our clusters?

Seriously, that silly gauge seems to me to be a JC Whitney add-on by BMW marketing to sell cars in the showroom.

Do people 'really' look at that thing fluctuating while they're driving?

I'd rather use the cell phone!

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