Any ideas on this

[iam]

Hi all.

Can anyone tell me what reason an engine would return 18-22mpg when in one car (540i) and less than half that about 10mpg in another (e30) even without a lead foot?
I'm guessing something to do with the ECU. The exhaust is a straight through one. Would that also have an affect?

Cheers
Iam

[Jean]

o2 sensors? is the dme getting the road signal? is the operating temp good?

[glucklich21]

Injectors? When mine were bad they were just dumping fuel into the engine. I burned through half a tank in 40 miles. :/

[iam]

The engine came out of a full bmw service history (110,000m) which I owned and drove for a year previously and it was driving spot on right through to wapping into the e30.
Anyone have a link to cleaning out the injectors?
I did have to change the fuel pump due to trying to turn over the engine with no petrol in the car for too long. It burned out. Could I have possibly been sucking crap through the line and blocking the injectors?

[Jean]

Can you verify if its running in the correct map? Did you do the wiring?

[iam]

Think i've found the answer. Changed out the standard 540i air box which I put in shortly after buying the car, for the cone shaped air filter which it was running when I bought it. I instantly and consistently have got an extra 6 mpg. Leads me to believe the map must be more aggressive.
Anyone agree?

[The Dark Side of Will]

So you're now at 16 mpg? There's still something very wrong.

Definitely sounds like an engine management problem.

What MAF are you using?

[iam]

standard MAF. Straight through exhaust (no cat or back box.) the car was raced on the previous engine so I'm convinced it's been remapped. Am getting the air/fuel ratio corrected soon.