Exhaust sensors-E-TECH 16V

[BASHO]

What exactly do the 2 exhaust sensors on the -E-TECH 16V actualy control , I'm for cold start and idle on the upstream in the cast manifold and fuel on the downstream in the exhaust pipe just after the cat.
But-
I realy am guessing as I know SFA about iether as fact.
Can anybody help me out on this

[PrecisionBoost]

The first Oxygen sensor in the manifold controls all air fuel related calculations in "closed loop" operation.

The secondary Oxygen sensor is located after the catalytic converter and it's only purpose is to ensure that the emissions systems ( catalytic converter ) are functioning correctly

During cold start and wide open throttle your car is in "open loop" which means it feeds in fuel without looking at the primary or secondary oxygen sensors.

It's only when the car has warmed up a bit that the ECU jumps over to closed loop to see what the oxygen sensor has to say about how rich or lean the engine is running.

[BASHO]

Thanks mighty for that---now -he -he --if I removed the cat and downstream sensor would I would get a check engine light ? if so , could this be negated in any way and what result would not having the downstream sensor have on the overall engine opperation ?

[PrecisionBoost]

If you remove the Catalytic converter and secondary oxygen sensor odds are your not going to gain any significant power.

In short..... yes.... removal of the secondary O2 will trigger a check engine light.

You can buy a "secondary O2 sensor simulator" designed for the sole purpose of making an ECU happy when you remove the secondary O2.

Most of the time this is when you have high performance turbo cars like mine.... where they run very very rich.

That is to say it's so rich that if I did have a catalytic converter it would be plugged in a week's worth of driving.

For turbo cars rich is good.... rich is safe.... rich keeps a connecting rod from blowing out the side of the block and making a big hole in the hood.

But for slightly modified naturally aspirated engines the removal of the 2nd sensor and cat will cause more problems than it solves.

[wolfsreign]

so, precision, how do you pass smog? if you run rich? and the O2 sensor faker... wouldnt the smog computer use the OBD to check to make sure the O2 is at right levels?
~wolf

[BASHO]

I ask as I've seen Exhaust extractors offered which look well made but don't allow for the the upstream sensor or Cat to be retained, rather --as I understand the somewhat un-english explanations-- the upstream sensor to be relocated in the downstream sensor position with the aid of a wireing extension (not provided suprise!--not) which obviously leaves the downstream sensor short of a hole and an exhaust system short of a cat.
And an engine maybe starting to run like a three leged dog.

I'm thinking a better result would be obtained by replacing the factory cat (which is a bolt out/in unit) with a highflow metalcat keeping the centre section of the exhaust to retain the tuning pulse effect and replacing the rear muffler with a more freely flowing sports job (not necessarily a straight through) it would certainly be a sight simpler , probably emmissions compliant , more cost effective , no sensor movement required and hey--maybe a few of horseys gain.
I'm probably going to get for these thoughts though--but whatdoyareckon ?
I'm not after big power , just a tad more briskness.

When I want power I use this one