I'm going to be fitting a decat d/p to my classic (RB5) soon and I was wondering if the Lambda sensor has to be refitted.
Is there any benefit in not fitting it and will it cause any problems.

Thanks Bob

 

Well, the Lambda is still in the original d/p as it wont come out.
The new decat has a threaded hole that I have bunged with a bolt. Is this ok?

 

my decat has been sealed off and runs fine on just the front sensor (classic WRX)

 

Do any dash lights show up?

 

You MUST fit the lambda sensor, it tells the ecu how rich/weak your engine is running and allows it to control fueling. It will bring on the check engine light if not fitted.

Phil

 

no dash lights with no sensor in the dp
problems only arise when you remove the second sensor at the front in the headers

 

very true but there is 2 on the classic and i have no problems only running the one on the front

 

A difference in opinions here, anyone else?

 

i think you must be on about the cat on fire sensor which is in the lower part of the downpipe and is not needed, and as you have a classic you would of only ever had 1 lambda sensor fitted any how

 

Perhaps Domino is referring to the fact that there is one on the (is it headers or up pipe) aswell as the d/p.

My cat on fire/Lambda is more towards the top, only a few inches from the turbo.

 

I changed the exhaust on my MY98 Classic and there was only one sensor and it is near the Turbo on the DP. This is the Lambda sensor and I was told by those that know that it is needed for the ECU. So it's fitted on mine

 

The problem is that the thread in the d/p is smaller than the sensor thread, so it aint screwing in - nowhere near?

 

Sounds like a dodgy DP - I fitted a Ninja Fast Flow DP from ScoobyWorld - exact match with the original DP in all respects and the sensor.

 

It needs re-fitting mate, as said previous, the ECU will detect a fault if its not replaced, or it should do.

 

Sounds like the sensor your trying to screw in is the "Cat on fire" sensor. This is a much smaller diameter than the "Lambda" sensor hence it won't fit. Classics have 2 sensors, the "Cat on fire" sensor and a "Lambda" sensor. If your decatting the car you obviously don't need the "Cat on fire" sensor, this is the smaller sensor. The "Lambda" sensor must be refitted however as the ECU uses this to monitor/control the mixture when the car is cruising. On my 93wrx the "Lambda" is in the headers on the drivers side. On later classics it is in the downpipe. I just changed the down pipe on mine and the hole was there for the "lambda" but as mine is fitted in the headers, i just blocked it with a nut and bolt.

 

No, the sensor has a larger diameter than the threaded hole in the d/p.
It's a 99 classic so probably the Lambda

 

Is the hole you are trying to fit the sensor into at the top or bottom of the dp?

 

HTH it is a TSL sportscat fitted to a MY2000 car and shows the lambda sensor screwed in near the join with the turbo.



Nick

 

Bob has an RB5 which is UK MY99 the only Lambda is at the top of the Downpipe.

Agree with Barretts, you should fit it back on mate.

If the sensor doesnt fit it does sound like the wrong D/P for MY99.

Not sure if you can source another Lambda with the correct size thread, in theory that is all you'd need as long as the electrial connector fits the OE one.

 

Yea, somthing very strange here.

Although there are several lambda sensors fitted to the classic subaru's, they all have the same thread size, so as has been said, you don't have a downpipe for a classic car.

Phil

 

Thanks for all the responses. This is concerning me now.

The d/p fits a treat and the sensor is positioned as per the photo so I can't understand why the thread isn't the same.
The d/p must be for a classic as newage exhausts are made up differently to classics.

If I could source a lambda with the correct fitting this would sort the problem, or alternatively re thread the d/p Lambda hole.

Any more thoughts?

 

I have just measured the hole in the decat d/p which measures 12mm.
The end of the sensor will not even push through the hole so it's way off. The sensor thread is about 18mm.
Looking at the decat d/p Lambda fitting/threaded section, it looks as though there is an inner threaded section tac welded into position. Maybe if this is removed it will reveal the true threaded part?

 

even the new-age cars use the same size thread, is the d/pipe new or not??

you need to re-fit the lambda

alyn

 

**** it!

I am going to take the d/p and sensor to a local engineering shop and get them to tap the correct sized thread into the d/p.

 

Bob before you do that give these guys a call and see if they have an appropriate Lambda for you with the thread size you need.

PRODUCTS FROM MIDDLESEX TUNING CENTRE LIMITED - Equipment

Good luck, fellow RB owner and all that.

 

Update

I have spoken with the person I bought the decat pipe from and he had welded an inner bolt into the larger diameter hole as his car (93 WRX) had a smaller diameter Lambda.

All I have to do is remove the inner bolt which is tac welded into position.

 

Nice of him to tell you about that

 

I did ask him prior to sending the cheque if it would fit a 99 car.

Ah well, it will give me something else to do.

 

sounds like he adapted it to fit the "cat on fire" sensor, as the 93 WRX would have the exact same size Lambda fitment but it will be located in the front collector below the up-pipe....................

alyn

 

Is all the info listed here the same for a UK classic? Does it also have a "cat on fire" senser as well as the standard lambda sensor? And would refitting the lambda sensor in a sports cat down pipe do away with any lights appearing on the dashboard?

Cheers.