Hi, I have a small project and would like some advice on how to proceed.First some background.....

The car is a citroen DS of 70 vintage, it has fuel injection (bosch L jetronic i think) and gives non stop problems with controling the mixture and poor running (over rich). What I would like to do is replace the old bosch ecu with something more modern (omex, mega, emerald etc)to fire the original injectors. The engine runs with points at the moment but this could be upgraded to electronic with a off the shelf kit.

What I want to know is what do these type of ecu's need as inputs to control the injectors (lambda,engine temp, crank position etc)and what is the least I could get away with as this engine has no crank sensor and very little place to fit a trigger wheel.

So in short I would like to keep the original hardwear (it has a single throttle body with a throttle pot attached, an injection manifold with injectors and pressure reg, engine temp sensor).

Any ideas??

Marcus

An L-Jetronic would have some kind of crank position sensor, and it will definitely have a moving flap air flow sensor. Possibly you have the much earlier D-Jetronic system which uses inlet manifold pressure (MAP) for engine load sensing? The megasquirt can use MAP and throttle angle, and it can be triggered from an ignition pulse instead of a crank sensor.

If you can lock the ignition advance mechanism (both centrifugal and vacuum), and convert the points to a hall effect or opto-eletrical sensor then you could also run the ignition through a megasquirt.

Hi thanks for that and yes its a D-Jetronic system, Megasquirt looks good. I was hoping to instal a ecu to control the fuel just to make the engine run better but without changing the overall period look/feel of the car.
Now looking at the info on d-jetronic on the web....... looks like i have some reading to do!

Marcus

For MS you will only need coolant and air temp sensors. It has an internal MAP sensor and can take RPM signal from your existing coil. That's all you need. Crank position is only needed for ignition. Ideally you would have TPS as well for acceleration enrichment but it's not required, it can use rate of change of MAP to know you're opening the throttle instead.