2003 745li burning rich

[vrilman]

I live in an area with no emission testing so I removed the cats from my exhaust. More power and fuel mileage now but engine is running a little rich. Any help adjusting fuel air mixture would be greatly appreciated as I know it would help fuel mileage even more. Thank you in advance.

[White94RX]

How do you know the engine is running rich? You've removed the cats, so it's going to smell rich and stink, even if it's running properly.

Everything is controlled by the DME, and as long as the primary oxygen sensors are functioning, the DME should be running the optimal fuel/air ration for the engine.

[vrilman]

White94RX, I acknowledge your response and agree the DME is running the optimal fuel/air ratio for the engine 'with cats'. That is what I am wanting to be able to adjust for optimal fuel mileage and power. Was so much simpler when cars were carbureted, turn a screw and voila'. A side note, I also have a 1996 BMW 740 with the same 4.4 litre engine. I am able to adjust the fuel air mixture on it. It now gets 30.2 mpg on the highway at 60 mph. Averaged 25.7 mpg on a 1,200 mile trip with average speed of 78 mph. I would like to get my 745 to do a little better than it is. Since removing the cats I now get almost 23 mpg at 70 mph which is a decent improvement over the original 20.5 . If I were able to lean it out just a tad that would improve.