lambda problems

[kopron]

I did a Turbo conversion on Saxo 1,4 , 8 valves.
And I also changed injectors .
But now the problem occoured , that lambda sensor is not giving enough voltage 2 computer and to air/fuel meter ( gauges) .
It is shown as poor mixture , while exhaust is black , spark plugs are black, and everyone can smell gas on exhaust pipe.
( 2much fuel )

I changed lambda sensor with new : no change .
I changed lambda sensor with 4 others : no difference .

And as I measured, Lambda is constantly giving 0.185 Volts ( 2 poor mixture ), instead of cca 0.500 Volts ( normal mixture ).
Voltage for lambda heater, that I measured, is 11,75 Volts ( normal ? ).
At first I had placed Lambda before turbine .
Than I placed it after Turbo .
Still no change .

This problem occoured , exactly when i changed injectors .
But even before that, the car was not running smooth at low RPM's ( low idle, 2000 RPM ).

The computer is Magneti Marelli IAW 1AP 40 .
I had 2 change fuel map , to make the car running .
Before that it was even not runing .

I was wondering,if anyone has another idea, what is wrong ( why is too weak lambda signal) until I'm waiting on my friend-expert 2 come from Italy 2 Slovenia ( my country), on/in Monday.

Thank you 4 helping me .

Boschtyan

 

[kopron]

Oukayyy. Thanx 4 idea + info. But, what about , if I mount 2 lambda sensors ( since I have prepared exhaust for 2 sensors ), wiring htem sequentialy , so , that I could get higher voltage out ? Maybe this would also help ? What do you think ?
Thanks.

 

[fueliefan]

that would be a waste of time. If you're still using a narrow band sensor, as long as it's transitioning across ~0.5 volts the amplitude is not terribly important. Also, to carnage1, the ecu "should" have software filters and calibratable psuedo-PID constants to prevent oscillation. I haven't looked at megasquirt in while...
The easiest way to tell if the closed loop system is your culprit is to simply put the vehicle in open loop and see if it continues to oscillate. I would recommend doing this only under light loads (you stated it occurs under cruise conditions).

 

[kopron]

Yes, it somehow someway somekind oscilates somewhere at low loads .
But I didn't understand , what you suggest as solution . Loop = ? ).

Maybe you tought ; If I tested it without Turbine .

But I did, and problem was remaining the same.

Or there was something else that you were thinking about ?

Have a nice day .

Bostyan .

 

[Bribyk]

Get a wideband lambda and save yourself a lot of time. See link attached...

 

[kopron]

Well, when we'll mount M.S., we'll mount a wideband Lambda, just for adjustment of parameters. Than we'll change Lambda with ordinary.

Have a nice day .
In Monday we'll continue.

Till thannn, ... may Lord be with you .
C' yaa.

 

[fueliefan]

By closed loop, i mean the ecu is using the oxygen sensor to change the fueling. You should attempt to disable this and see if the engine continues to oscillate.

 

[kopron]

Yes, i also did disable oxygen sensor, but engine stil oscilated .

But, now, after this past weeks, we mounted MS.

And, a si predicted, it runs smooth almost as it should .

There are yust small "misfires" of the tacts-strokes, bu at least i can drive car normally, without small fast jumping oscilations.

And, so far on 1,5 Bars , it runs very very smoothly .
Next week we'll go on to 2.5 bar of boost.

So, the problem really was in the computer, a s I tought.

Well, next time, when i will go to a similar project, i wil be much much more careful, which computer the car will have.

Unfortunatelly, you can't know that, before, when you lower the compression ratio. Than this problem occour.

But never again I will do this on the same kind of car. Never.

Anyway, I gratefully thank you 4 your help + your time + cooperations + support , and I'm closing 4 now.

Bye, ... see yaaa, brothers, ... if not in this life, than "on the other side",

Boschtjan Zupanchich, Slovenia, Europe, Earth, ...

+ may Lord be with you.