N/A, 90% stock

hello g1,u car turbo or na a15??

9L/100km is highway driving - 110kph constant speed with air conditioner switched on...

Oh, I understand. Is your 9L/100km town driving?
The 528i fuel consumption I referred to was highway driving. Town is definately a different story. Then they are heavy on the juice.

Perhaps im not using the stock Hitachi carb, thats why my f/c is high.

About your 528i, i know about this car real well, i used this car before. While driving constantly at 110 or 120kph, the fuel economy meter shows abt 10L/100km. This is because a 2.8L engine has high torque and thus, a little touch on the pedal lets the car to maintain at high speeds ( enough torque to withstand wind resistance ). Even at constant 160kph, it shows abt 12L/100km only.

But its a different situation when accelerating from a still stand. Step the pedal gently and it shows 30L/100km...haha

Quote:

That is not good for a 1500cc engine.
My father's 1984 BMW 528i that he had in the past was automatic and it's fuel consumption was 11L/100km at a constant speed of 120km/h.

"""When I continued to adjust it lean, I lost quite a bit of power and my fuel consumption went up."""""

Wow...can that happen? I mean, power loss is something normal. But, how it can make the consumption go high is quite a puzzle.

So, shall i make it richer now?

I asked about the carb because I'm assuming that maybe the new exhaust flows a bit more than the old and now your mixture is not right. I think you may be too lean.
I recently played around with my carb jetting to try and get my fuel consumption to go down. I had adjusted it a little leaner and everything was fine. My fuel consumption went down. When I continued to adjust it lean, I lost quite a bit of power and my fuel consumption went up.

or,
now that I think about it some more, that super quiet muffler may also be more restrictive than the old one.

My main suspicion is exhaust instead of other things since this issue happened immediately after i changed the exhaust system. Within the next 300km after i changed it, i noticed the difference. It was real good before that, 9L/100km....and what else could go wrong during an exhaust setup swap ?...yeah, before anyone would ask, i'll clarify that there are no leaks found from the extractor till the tail pipe end....

There's no visible black smoke from the tail pipe too. Even signs of a healthy engine ( tiny water droplets from the tailpipe during cold start ) is there.

I cannot think that a exhaust can make your fuel consumption go so bad. Something sounds wrong.
Take it to a mechanic that has a gas analizer machine to see what it says about the exhaust gases.