for all u turbo guys were did u guys put ut o2 sensors,i mounted mine about 3 inches away from the turbo outlet,and im having a hard time getting a stable reading.Would i be better off with the o2 on the inlet side of the turbo rather then the downpipe?

before there i had it further away from the turbo outlet.moving it closer to the turbo helped but it still isnt right

 

On my truck I put it in the stock location in the T-coupe DP housing.

On the Cav, I'm finishing up, it's in the DP about 3" away from the outlet.

I haven't placed the O2 on the engine side of the turbine, simply because I believe it would give a false rich reading, due to the turbine holding the exhaust gasses in that piping. Same principle as tuning the fueling by backpressure. Also I beleiev the heat would have negictive effects on the O2 sensor.

Now that being said, the '89 and '90 TGP had the O2 on the inlet side to the turbine.

 

thnx man,i just ordered an lm-1 wideband o2 kit,caus ei need to know whats really going on with the af ratio,all the sudden the cars running like crap.ecm says its running lean/narrow band gauge says its running lean,but if ya stand near the back of the car u can smell the gas in th ex.and after pulling the plugs they all smelled liek fuel also

 

You shouldn't get either problem. The O2 only measures the amount of Oxygem in the stream, backpressure doesn't add O2 to the exhaust, so you should be reading fine. O2's also work BETTER the hotter they are, until the point that they melt the insides at about 1800*F. Volvos and MANY other manufacturers put the O2 just in front of the turbo because it gets warmer faster, which means it's online faster.

 

yeah not enough back preasure can lead to a fe wproblems with an o2,my problem happens to be the o2 isnt reaching its operating temperature,so im swaping out th esingle wire o2 for a heated 3 wire o2 this weekend

 

*sigh*

Backpressure or restriction will cause less exhaust gasses to escape from the exhaust system, thus creating an artificially rich mixture, in the exhaust and even the combustion chamber, due to less gasses being able to be let out.

This is an old tuning trick, from way back when tuning cars for higher performance was still in it's infancy.

I have also been able to observe these changes, by playing with the plates on my SuperTrapp muffler long ago.

The part about the O2 sensor heating up faster, is true, but the difference is seconds, making it negligable.
Yes the temp will need to rise extremly high for an instantanious sensor failure, but prolonged period of just higher temps can cause the same scenario to happen.

Either way, will work, I just prefer down stream of the turbine, since it seems safest for the sensor itself, and give IMO a possibly more accurate indication of what is actually coiming out of the engine.

 

So this is before computer controlls and Closed Loop Systems?

I think what we all need to do is just switch to EGT sensors and be done with this stupid O2 sensor debate...lol

 

LOL, exhaust restriction still has an effect even on computer controlled engines.

EGT is even less indicitive of what is actually happening in teh combustion chamber....

EGTs can rise, if it's rich or lean.

 

I never said it would be a better conversation...just not about o2 placment, there's only 1 place to get accurate EGT readings, there's no dobt about that.

 

I think we're going in two different directions, I was not talking about the discussion of EGTS, I was talking about how they react, being that if the mixture is rich OR lean the exhaust gas temp will rise, to me, being less informing than a narrow band O2 reading.