EFI and mileage

[Tony Bryant]

> From:          Jason Greene <verde1 at us.ibm.com>
> To:            <diy_efi at esl.eng.ohio-state.edu>
> Subject:       EFI and mileage
> Date:          Tue, 3 Mar 1998 21:23:14 -0500
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> 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.
> 

Check your water and air temperature sensors & associated wiring.

Also, are the injectors,air flow meter,pressure regulator & ECU  
ALL from the same car?