This is a sign that your butterfly is to big.... otherwise you can tune it easely. Even my BX-sport with 2 double carburator is running decent on speeddensity......

Are you sure you have a decent map reading or is it all over the place, then put an fuellfilter in line and a restictor .8mm (I always take a weldingtorch thingy)..


When it doesn.t work you can tune for Alpha_N or hybride

Is 36mm throat too big? I don't think so...

Ok, there is two 36mm throat, second start to open at 70% throttle opening...

But still, there isn't almost any vacuum when throttle is opened...

There isn't any restriction at MAP -line, 160cm hose with 4/2mm hose, very steady MAP-reading at all...

And yes, I use Alpha_N, no way to use Speed Density.

Maybe I have made everything wrong, in last five years..? Even when MS is working fine...

I guess so.......... (sorry don't want to be rude)

A) Have you set the proper Mapsensor in the settings of Megasquirt????????

B) What throttlebody are you using and where is your maphose attached I think something can be wrong there also....

Every Visa engine runs on map with the little vacuumbox (giving more advance at cruising speed.

Marks 4x4 1-2-spark ignition runs on map with Visa vacuumbox

My 1-2-spark 2cv runs on Visa vacuumbox and you can exacty point out with the throttle when the vacuumbox kicks in...

My turbo 2cv runs speed-density Megasquirt with or without turbo to 1.5 bar on boost....

Even my BX-sport runs on Mapsensor = speedensity

So yes I think you are doing something wrong.................(again don't want to be rude)

MS and 2cv works even finer on speed-density trust me I know what I'm talking about.....

My throttle body is 38mm from Daewoo Matiz, similar size 3cylinder engine, 28mm would be better!
I had unstable map until I put a fuel filter in line, it still bounces a bit put it is tunable. Where do you put the resistor?

Harley

That is funny thing, almost everyone who has played with Megasquirt, says the same. Alpha_N is something between very hard and nearly impossible to tune, but I didn't find any difficulty with that. With Speed Density tuning was PITA, and after changed Alpha_N tuning became so easy that it could be...

I'm only telling what I have experienced, and if someone come and say Alpha-N is the wrong way, I will ask why. And if that person can't be justify his opinion, I don't care much. That is because I have used both, and I'm pretty sure that Alpha_N is for this kind of solution, and Speed Density is when I get my supercharger on...

Lpgo, You haven't been rude, and there isn't an absolute true on these machines...

I've got the same in my turbo 2cv and in my opinion it is just to small and I would prefer a slightly bigger one (for a standard 2cv) for a supercharged 2cv it will be perfect.. for a turbo2cv it is to small when driving in the non-boost??? region.......
again my opinon.....
Put the resistor near the inletmanifold, put the fuel filter near the ecu...........

I now this is diffrent to a mapsensor the only thing I want to tell here that a 2cv/visa has a steady mapreading switching the switch on and off at a certain vacuum, (will test this week when it switches so that I can simulate it with the onboard 1-2-spark mapsensor, its a start for me to implement a vacuumsensor, in a later stadium I will make it infinitive with programmable more or less advance, cruising along in my 2cv the switch opens at about 90kmh.



I'm not confused I have only mentioned speed-density........


. Because at a certain throttleposition and rpm there are more possebilities, is the car under load or is it cruising or iddeling along.
You have only 1 fuelload then so it isn.t aqurate enough. Okay on fuel it will work but on lpg there a smaller bandwidth (about 1.2 to 1.6 arf) to make the car run so it doesn't work for me.

I had my BX-sport running at the beginning at A/N, but when I drove a away for instance, give a little throttle, let the clutch come up the engine needs more fuel, but hey the throttle is at the same place so it won't get more fuel and the engine starves, doing the the same at SD map goes up engine gets more fuel, car drives nicely away......

N/Ais easier to tune for me too.....




So with supercharger suddenly SD works???? and without supercharger it doesn't...... Ahem



But hey you are right there are more possebilties here have you ever run hybride,,,
1. tabel A/N 2. table SD works great too when you have eratic map readings........


p.s. where drifting off here 1-2-Spark.......

Back to Knock sensor.

I agree with LPGO on this, HEREis a good article about how to implement a Knock sensor into megasquirt.
We all know how loud and rattly the 2cv is (a lot due to no water jacket), tuning a knock sensor and finding an appropriate place would be problematic at best. 3 switchable ignition curves that are also tunable is a perfect alternative.
The best way to test if a knock sensor is working is to hit the block with a hammer... I don't know about you but sounds like my engine is already hitting itself with a hammer!

Harley

Ref - my 1-2 spark installed. Please see my Dyane 6.52 thread for photos

This evening I made good progress implementing the Mapsensor.

The pointer at my laptop screen is now moving when I suck or blow into the mapsensor and it is giving almost the reel numbers so this is great, I made a little table but it doesn't count btween 2 points it jumps from 1 point to the other. But this will far more be better already then the Visa vacuumbox.

I uploaded a little video at youtube but at the moment I can't find it; as soon as I find it I will post the link here......

Well heres the link http://www.youtube.com/watch?v=cGC12_6WKvw


It is reel stable (running dry) so this is al beyond my expectation.......

I noticed I'm reely good in sucking (almost vacuum) but my blowing sucks; only (.2) bar of boost in my longs.. (no Gay-Joe this is not what you think):lol:

I didn't dream I could make this to work so quick so I dont have a hose to test it in the car
so I will test next week......

to do list
-linear maths between two points
-writing software so that you can tune more or less advance under vacuum and boost with computer.......