EFI and mileage

[Carl Summers]

Jason Greene wrote:
> 
> Hello to everyone.
> I'm new to the list and I have a question.
> 
> I put EFI on my 72 Datsun 510. The car never actually came with EFI. I used an
> ECU from an 81 200sx and the manifold from a Japanese model car.
> 
> Well my question is about my mileage.  Why did my mileage go down by almost 1/2
> (30mpg down to 17mpg) when I went from the carburettor to  the EFI?  I've
> played with the Air/fuel mixture and it never improves.  My engine size is a
> 2.2L and the injectors came from the same size engine that had a cross flow
> head (mine doesn't have crossflow). Would any of this make a significant
> difference?
> 
> I know of 2 other guys that have done the exact EFI conversion and get great
> mileage. I've tried replacing the ECU but it didn't make a difference. Does
> anyone know of a sloution or any ideas thatI can try?  Please help......
> 
> Thanx in advance,
> Jason G.
Hi Jason,
   You might check your O2 sensor,,as these start to fade they produce
less voltage and subsequently tell the computer the engine is
lean,,,also if the computer thinks there is an egr valve and there isn't
it alters the AFR when it thinks the egr valve is open and you lose
efficency..HTH's
-Carl Summers