average fuel going crazy

[lionkingns]

So after a bit of wire tracing and and adding managed to get my BC working on my '97 e39 petrol. Everything works but the average consumption for some reason goes crazy while standing in place, i reset it, while driving it is around 10-12L/100km which is normal, than I stop at a red light and it starts going up for no reason, and after a few red lights I get to 15-16L which is way of since I did check it at a constatnt drive without stopping and it stays at 10-12L. I guess I need to code something, but have no idea what to check , but I do have all the tools and programs to do any coding so that is not the issue, just someone pointing out what to do. Oh and the current consumption needle goes to 0 while standing still, so I guess that works ok.

I know this is not a real issue and something that effects my driving, but it annoys me for some reason

[edjack]

I suspect there is a defect remaining in the wiring, or a connector.

What caused the problem in the first place?

[lionkingns]

In there first place it did not have BC at all, changed the blinker handle for one with a BC button, and added the wire to the cluster that activates it

[balidawg]

Look at the fuel trims. That will indicate the actual health of the fuel management system. Ideally you want both long term fuel trims to be between -5% and +5%. Might as well read the DME trouble codes while you’re at it. Report back what you find.