hi guys i have 2002 e46 bmw compact 316ti. recently had replace two coils as they where knackerd and causing a misfire so now that ive done that im getting really bad fuel consumption for my money ie. 50miles for £20! could this be that with the coils been knackerd its been over fueling and burned the lambda out or somthing along those lines? any help is greatful, Thanks Kris

wow could be a million and one things there m8 check the spark plugs see if its overfueling

This should help

http://www.classic-car-magazine.co.uk/articles/spark_plug_colour_guide_chart.html

Going with Lliam on this one...

Over fuelling - Maf giving wrong signals, i.e. Telling ECU that the engine is STILL cold...

Over fuelling (2) - Throttle body coked up, letting less air thru...

Over fuelling (3) - Injectors in poor condition...

Over fuelling (4) - Fuel pump pressure way too high for injectors to handle...

Cylinder firing - Spark plug(s) not performing i.e. Pre-combustion, hence lack of power...

Cylinder firing (2) - Oil ingress causing less air/fuel mixture to enter cylinder (Coked Plugs)...

Cylinder firing (3) - Engine timing is "out" ... It happens....

Cylinder firing (4) - Coil breakdown... May still fire the cylinder but with little or no effect due to a more cooler orange spark ! (in combination with plugs)...

Post firing - Lambda sensors/emission control maybe giving poor results to ECU which can work either way in the fuelling of cylinders...

Idea number one... Get a friend to hold the revs at 2500 for a minute or two while you have a close "Smell" at the back box (not too long tho or you'll collapse lol)... If it stinks of petrol then refer to the above... Ignore any water droplets as all cars do this, notice the colour of the burnt fuel at the back box and let me know, Kris....

Just ideas buddy

Just to add... If the Air/fuel mixture is optimum all the components are working as they should then consider changing to a hotter or cooler plug setup...

DAZ

How old is the fuel filter?

thanks for the replys guys.

daz thats some useful information thanks alot im gonna try the holding revs tomorow and try get it on dyignostics on thurs.

im unsure of fuel filter i will ask my friend tomoz he serviced it but i think he replaced it.

thanks. kris