Fuel signal

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lekman
Experienced MS/Extra'er
Posts: 164
Joined: Thu Jan 17, 2013 3:01 am
Location: Sweden

Fuel signal

Post by lekman »

Maybe I already asked this. My old audi has an "onboard computer" (don't know the English for this). the fuel (amount) signal is a potentiometer attached to the mechanics of the K-jet that was there before the ms.
Is it possible to produce a resistance signal from the ms (voltage signal?) that is based on the pulse width or perhaps on the duty cycle of the ms. If just a voltage, can this be transformed to a resistance signal somehow? Servo motor?
Anybody who has dealt with these questions, to make the old on-board information services to work with the ms?

/Lars
DaveEFI
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Posts: 4175
Joined: Sun Apr 15, 2012 12:55 am
Location: SW London, UK

Re: Fuel signal

Post by DaveEFI »

Dunno if it helps, but had the same problem on my Rover SD1. The trip computer on that counted a single injector pulse to measure fuel consumption. I'm using PWM to drive the low impedance injectors directly, and this confused the trip computer.

Jaycar do a kit which measures the current flow in the +12v feed to one injector. This is converted to an on/off pulse similar to the original.

http://www.jaycar.com.au/productView.as ... TID=965#11
Rover SD1 3.5 EFI
MS2 V3
EDIS
Tech Edge O2
London UK.
lekman
Experienced MS/Extra'er
Posts: 164
Joined: Thu Jan 17, 2013 3:01 am
Location: Sweden

Re: Fuel signal

Post by lekman »

Thanks Dave. Now I remember that we have discussed this already. I will look at the Jaycar cit..
/Lars
DaveEFI
Super MS/Extra'er
Posts: 4175
Joined: Sun Apr 15, 2012 12:55 am
Location: SW London, UK

Re: Fuel signal

Post by DaveEFI »

I'm not sure how the K-Jet system works. Mine was originally L-Jet. Carb cars of my make which had a similar OBC used a flow meter in the carb fuel feed - but this wouldn't work on the EFI due to the fuel return. So on EFI it counted the time one injector was open. The actual OBC is the same on both, but the EFI has an adaptor unit between the EFI and OBC. Not quite sure what that does exactly.

On my car, the OBC is a stand alone unit made by Smiths. The original injection Lucas/Bosch.

It's possible yours had a later model which used a later injection system but the same basic OBC?
Rover SD1 3.5 EFI
MS2 V3
EDIS
Tech Edge O2
London UK.
lekman
Experienced MS/Extra'er
Posts: 164
Joined: Thu Jan 17, 2013 3:01 am
Location: Sweden

Re: Fuel signal

Post by lekman »

The OEM-K-jet has a potentiometer that is attached at the mechanical air mass meter.. I therefore need a resistance signal for the fuel information..
Isnt it possible to get some additional processing within the ms1? perhaps a signal that can drive a servo motor?
/Lars
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