Ipgo
I really like holland so its a good excuse to come over!!

No problem then, see you next spring/summer???

Hopefully!!

bussy at the moment making a new order of electronics to make 5 units with mapsensor,
At the moment I'm not really satisfied with the mapsensor, (still got spikes) but maybee with new electronics and new Pcb it will work better...... to be continu.....

Yesterday all the electronics arrived to complete 3 units with mapsensor.....


Still working at the software too but not satisfied yet, it works (advancing, retarding ignition by inletmanifold airpressure) but theres still to much jitter??
between the numbers calculated in the microcontroller comming from the mapsensor so not good enough to deliver yet...

Now I have new cassings (old casings never arrived) so I can make a new PCB to fit the new cassings and with integrated mapsensor.....

With the new pcb's I can (in theory) do injection (sequential for a 2cv) as well

Also develloping the software so that I can have more then 45 degrees TDC of advance (so before passing sensor, so that you can make 45 degrees (fixed) + 20 degrees (map) so in total maximum 65 degrees of advance BTC.... should be enough to make your 2cv as
fuel-economic as a C1.........

Can programm also that when you release the throttle completly (say above 1000 rpm), no fuel is delivered to the carb ( shut the electric valve in a Visa carb) so just like all modern cars do too....

Your progress is impressive, but shouldn't that shut off fuel to the idle jet/circuit? Cutting all fuel delivery would leave you with a partially or fully drained carb after sufficiently long engine braking.
But if you develop that, you should also think about a stepper motor for idle RPM control and opening the throttle just a little bit so that engine braking wouldn't be so strong, to make the "zero fuel consumption" time much longer
On one trip I averaged 5,3 l/100 km in my standard ignition 2CV @ 75 kph over a distance of 220 km. I wonder how much I can improve with this. I love experiments like that, gotta start saving money for 1-2 Spark

I thought exactly the same, but then I realised the valve on the visa carb must be an anti run-on valve which would shut off fuel to the idle circuit. I can't see any reason why Citroen would have fitted a valve that cuts all the fuel to the carb. I think the detail was lost in translation.

I'm not sure what would be better here, throttle open, or throttle closed. With the throttle open it is easier on the induction stroke, but with throttle closed it is easier on the compression stroke because less air has got into the cylinders. I know when turning my engine on the starter, it always turns over quicker if I don't touch the throttle pedal. Also kick starting a motorbike is always easier with the throttle closed.

Yep,
just lost in translation (NL to PL? ), as Ipgo's idea of shutting down that valve would isolate the idle circuit.

Also, engine braking will be strongest when a throttle valve is completely closed on the over run, which is why diesel engines (which don't have a throttle) use different methods of simulating what happens in a spark ignition engine.

ken

Yes, engine braking is essentially the effort it takes to pump vast amounts of air through this small opening so closed throttle means greater deceleration, but now that cars have the fuel delivery cut off during engine braking, the main purpose has become economy. I'm almost certain many modern cars open up the throttle a little bit allowing us to coast for much longer distances. My mom's Hyundai Getz seems to be able to go for around 1 km or more from 80-90 kph until the engine is "back on" on revs around 1000 per minute. Doesn't engine braking in a 2CV seem very sharp compared to newer cars?
Joolz, it's easier to turn over an engine which takes in less air/mixture because effective compression ratio is smaller, but without combustion the mass of air becomes a gas spring, which means only a small portion of the compression energy is lost as heat. That's why diesel engine have to use some subsitute of the throttle for engine braking, as Ken has mentioned.

to cut fuel at modern cars is only for fuel economics, it has nothing to do with
engine-braking.

Most modern cars have a idle valve alowing extra air into the engine when could (sort of choke) it is possible to open it when the car is cruising along..... however I think the less air gets into the engine (vacuum when throttle is closed) the less compression there is so I think cruising along with throtte closed works best........

Diesel engines brake on exhaust brakes (trucks) operated mostly on air I've drove them during my army time it was mandatory back in '87......

Do you remember the old bus in Most (WM chech) driving to the town and back the driver was double clutching/engine braking all the time when shifting up and down......