What's the sensor in the middle of the exhaust called?

[adey]

Help please: My K-reg GTI-R has a Mongoose exhaust, with a sensor about half-way down, where I *think* there would originally have been a cat. Is this the lambda sensor or not? The reason I'm unsure is that the workshop manuals only show an "exhaust gas sensor" being at the outlet of the turbo, and don't seem to mention anything downwind, at least, not for the SR20DET engine.

My exhaust need replacing to get it through its MOT, and this sensor in the middle is so rusted up it's going to need replacing. But without knowing what it is, this won't be easy.

 

[cojack]

It's a temp sensor fella. mine was rusted up but it came out no messing. Could always heat it up a little to get it out

 

[AJ4]

more specifically, its a cat temp sensor. The idea is that it warns you not to park over piles of dead leaves etc if the cat is too hot, via the little 'sizzling sausage' bulb in the dash.

 

[DOT2DOT]

So it doesnt matter if its not wired to anything??? Or does uk model not have this light and the sensor is just blocking a hole on my car?

 

[geetee]

tis only wired to the warning light on the dash.

makes no odds if it's connected or not.

Cheers
Graham 8)

 

[NISM0]

temp sensor??

are you sure its deff not the lamder probe which mesures your gas emisions then lets the ecu ajust fuleing for emissions, if it is it needs to be connected, of course i could be wrong but most cars with a cat have to have this sensor ive also been wondering if it is a temp sensor why is it there??

 

[AJ4]

more specifically, its a cat temp sensor. The idea is that it warns you not to park over piles of dead leaves etc if the cat is too hot, via the little 'sizzling sausage' bulb in the dash.

I'll quote myself

The lambda sensor is mounted next to the turbo, if you look down the left front side of the engine you can see the wire loom going to it.

You don't need the lambda sensor either, like you said, its only for emmisions. If its well tuned its not necessary.

 

[DOT2DOT]

You don't need the lambda sensor either, like you said, its only for emmisions. If its well tuned its not necessary.

Balls.

 

[AJ4]

lol, well maybe if you have an old shitty oil burner engine its necessary, or just love seeing your idle jump around as the 14 year old system still tries to work :roll:

 

[geetee]

AJ wtf are you on about???

The cat temp sensor is just for the light in the dash - not needed.


The Lambda sensor as you rightly say is in the turbo elbow. This is needed.

The Lambda is used by the ECU to regulate the air/fuel mixture when in cruising or part throttle situations. It's called closed-loop feedback.

:roll:

Nothing like an owner's club for finding accurate information is there!

Cheers
Graham 8)

 

[AJ4]

explain to me exactly how a lambda sensor is needed ?? My car is mapped to run at 14.7:1 on the first 10 load points, and every point up to 4000 rpm. What exactly do I need a lambda sensor for ??

You could argue that the manufacturer fits lambda sensors, so they must be needed. Yes, if you don't have a mappable ECU. The reason they are fitted to production cars is to counter manufacturing tolerances affecting the base map, changes in ambient temperature, and years and years of all the little parts of the system going in different directions.

Your basically saying that you need a lambda sensor, because its impossible to tune a car to give the right air/fuel mixture at different load points. I think more than a few people actually beleive in 'mapping', its not an urban myth :lol:

Besides all that anyway, I drive a 4wd rally car that drinks petrol like my missus drinks alcopops, why the feck would I care about emissions anyway ?

Amazingly enough, in the last 20 years I've owned dozens of old cars that didn't have lambda sensors and they still worked fine :?: :?: WTF is that all about then ? :lol:

 

[Fast Guy]

Curious, if it isn't needed, why does a faulty one cause you to run rich?

 

[Odin]

My car has the lambda sensor switched off and the car still works and runs fine, And blow me down with a feather it even pasted the M O T :shock: :roll: :lol: :lol: :lol: :lol: .

But I do have Motec ECU fitted , Makes no difference at all if its switched on or off :? , Funny that .



rob

 

[NISM0]

wo man

didnt meen to start a scrap, i just thought you had one infront and behind cat , cheers, oh why do you need a temp sensor at the cat??

 

[Odin]

Re: wo man

oh why do you need a temp sensor at the cat??

Its purpose is to let you know if the hot cat is likely to set the dry grass or under growth you've parked your motor on, On fire lol .




rob

 

[AJ4]

Thank you Rob !!! 8)

The reason the car runs rich with the faulty lambda is because the standard base map is overly rich.

I can't see how people can't understand, if they believe you can tune a car for power by adjusting the AF ratio, but you can't adjust the AF ratio at idle for some reason... :?:

<bemused>

 

[AJ4]

Re: wo man

Its purpose is to let you know if the hot cat is likely to set the dry grass or under growth you've parked your motor on, On fire lol .

I've already said that, twice !, in this very thread. This has got to be some kind of wind-up, surely ??

 

[Odin]

Thank you Rob !!! 8)



I can't see how people can't understand, if they believe you can tune a car for power by adjusting the AF ratio, but you can't adjust the AF ratio at idle for some reason... :?:

Your welcome fella, And to answer your question its because most of them don't know there head from there ar5e lol . Oh and they probably listen to there tuner of choice to much :roll: :? :? .


rob

 

[cojack]

Right this may be me being a mong or my cat temp light don't. When is this light ment to come on. I only thought it came on if the cat was overheating :?:

 

[NISM0]

ahh ha

ive actualy got a mate who got stuck in a field of straw, he kept wheel spinning then smelt smoke, he got out the car and the next theing he knew wooof a brand new pesat up in smoke, doh, good job i don't have a cat lol, cheers