Two Lambda Sensors - Advice Needed - Captain/BenR

[Simon]

My car has two Lama Sensors. One before the cats and one after. My understanding is that all phase 2 cars also have two Lama sensors.

Im investigating getting a custom decat pipe made up which will have sockets for the two Lama Sensors.

Devil do one for cars with one Lama sensor but that is no good for me.

First Query:
Will car run OK if I fit custom decat pipe that houses the two sensors?

I have heard stories like the 2nd Lama sensor will not get a correct reading and the ECU will go into secure/limp mode reducing power to a minimum.

Second Query:
If this is the case would something such as a UNICHIP be able to just ignore the 2nd Lama sensor thus car works fine.

Could I replace the Lama sensor with a resistor. E.g. if you find out the voltage at which the probe runs with ideal mixture, you can replace the probe with a compatible resistance, and thus remove the cats with no problem.

Also.

If it is as straight forward as a decat pipe that supports two lama sensors and no other changes would anyone else be interested in one?

 

[BenR]

i can only remember looking at one sensor after the cat...but if there is one before and one after, then why the need for the brackets fore the sensors if the sensors are not in the cat your replacing?

on the sensors, stoichiometric is 0.5v and it will vary to 0.2v for rich and 0.8 for poor.you can test this with a good volt meter. but if you get a resistor, just get one for 0.7-0.6v so it thinks its running slightly lean and itll run more fuel, however if the ecu cant tell the mixture and if you have mods, then it could be detrimental to performance.

 

[BenR]

oops,

0.5v = stoichiometric (perfect)
the lcoser it get to 0,2, the richer it is, the closer to 0,8, the leaner it s running.

 

[Simon]

The 2nd sensor i.e. the one that I described as being after the cat. This I believe is actually located in the cat itself. So if I remove the cat then I have no where to place the sensor.

I think you are right though, the 1st sensor is located before the cat and will not be affected by the removal.

Therefore if I get a cat replacement pipe made that can house the 2nd sensor then will everything work OK ??

 

[BUTRE]

actualy this of the 2nd lama is a concern of a friend of mine who owns a polo 16v.

anyone else for a hint in this subject?

 

[BenR]

i would guess (ask capt) that its for the engine to capare the two, cause emissions testing are only @ a cetain rpm.
and with euro 3 being the same as euro 2 emissions levels, just without the 5 min warm up time, the engine needs to ge the right emissions FAST i.e. straight away!