Peugeot 1.6 tu5jp, will engine run reasonably with exhaust open

[Berridale]

Just installed this Peugeot 206 iron block engine into a Berlingo which previously had the later alloy 1.4, changed everything electrical but stopping at cutting the exhaust under the gearbox until i solve the poor running.
.
Has one exhaust sensor on the downpipe at present.
I will weld in provision for the extra sensor later.

Does anyone remember if they run reasonably with the open exhaust or does this throw the engine management out?

Or am i looking at another cause.

 

[seasink]

There are oxygen sensors at each end of the cat converter. Either disconnected will throw a fault code, and probably cause the depollution behavior. The engine should still at least start.

 

[Berridale]

Thanks Seasink,
do the two sensors at either side of the cat compare the values?
So the cat is essential for the sensors to work?

The problem is late engine has the cat below the exhaust manifold but the early engine from 206 and early Berlingo has it under the car.
So at present no cat.
Is there any way to get it to work without the cat?

Will pop over to the farm and get the cat from the P 206 see if i can graft it in.

 

[seasink]

The upper oxygen (lambda) sensor is the control sensor for the combustion. Legislation requires a second sensor after the converter to detect converter failure - it produces an undulating output on the signal conductor, whose amplitude voltage, which increases with age or damage at the catalyst, determines if failure has occurred

Taking the cat off would also trigger failure in the aft sensor. Much the same as a missing sensor I suppose. The important thing is what will the computer do to combustion in cat failure mode in your car. My guess is that it will allow idling.

Edit: a 4 wire sensor has a 2 wire heater circuit.

 

[Berridale]

Seasink,

great explanation.
will try to get the exhaust/cat sorted.