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Fitting a decat?

Cookson

Cookson

ClioSport Club Member
Car  Mk1 Audi TT 3.2 V6
OK, so not wanting to have my management light on all the time, i wondered what the score is with decats and lambas.

I have been told to leave the front one in, but bung up the rear. Leave the rear plugged in, but fire the car up with it out in oxygen, then bag it up and tie it out of the way.

Is this correct?

Or plumb them both in and just deal with the management light?

Finally, should I give them a swap round in the even my first lamba is a little "worn out"??
 
as in put a bung in the hole in the pipe, but leave the lamba plugged into the car, lol
 
Fit it all properly, your engine management light isnt guaranteed to come on anyway. However, if it does buy yourself a code reader off ebay (£20 inc delivery iirc) and clear the fault. Thats what i did and the light hasnt been back on since.
 
Just plug both lambdas in. You may get the light, you may not. I didn't.

If it bothers you so much then buy a code reader to erase the fault when (if) it appears.
 
What's the big problem with the light being on anyway?

It's dead tiny and out to the side, not like it's a massive thing in your face that beeps, like a golf lol.
 
I've had my decat fitted since March with no engine management light. Probably just luck of the draw if it comes on or not.
 
All above points valid, left both my lamba's in and didnt get a light untill months later when i was sat in traffic for ages so i got a code reader and cleared it. What ever you do dont run it with the front one unplugged, it will run sh1t, 2nd one just reports back to the ecu a lower reading to the 1st (or if its the same the light comes on)
 
OK, will try to get it chucked on this weekend. Will leave both lamba in and if it throws a code, get it cleared.
 
i bunged the second hole and unclipped the lambda from underneath the car then tapped the s**t out of the connector to make sure no water can get in
 
Cookson said:
as in put a bung in the hole in the pipe, but leave the lamba plugged into the car, lol
Click to expand...

Ahhhh makes sence now! :)

I didnt think that would work as it would read as the CAT is working too well and throw up the light again? But if its tried and tested... i may just do this.

I have the wee light RS Tuner coming this week so I'll clear it with that.
 
OK, going to give this a go tomorrow. I was going to pay someone to fit it, but it surely cant be that hard??

I mean, its just a case of sliding the old one out, and the new one in yes?? I know space is an issue, but do I need to be undoing the dogbone and moving the lump around etc etc??
 
Its a 10 min job, mine used to be on and off more times than i can remember!
(ie: put cat back on for MOT then take it back off after MOT, also sometimes got board of the loudness etc)
So not worth paying someone to do it.

Only problem you may have are the bolts rusted up, spray with WD40 and leave for 10 mins before you try.
 
Well, i went to the garage, as i coulnt even get my WD40 down there, lol

Suffice to say it all went well. In fact, brilliant.

MPG has gone from 33 to 42 yesterday. Sounds a bit raspier than standard between 3-4k, but its not intrusive
 
Cookson said:
Well, i went to the garage, as i coulnt even get my WD40 down there, lol

Suffice to say it all went well. In fact, brilliant.

MPG has gone from 33 to 42 yesterday. Sounds a bit raspier than standard between 3-4k, but its not intrusive
Click to expand...

nice one :)
 
Out of interest, how much did you pay to have it fitted?
Looks like a bit of a pain to fit so I'm sat at my local exhaust place waiting for them to have a look to quote a price for me.
 
As far as i know if you fit a decat pipe and the light doesn't come on then it means one of the Lambda's is knackered and not reading the emissions/Co2 content right, i changed my pre cat one recently for the post cat sensor and it made a difference in the pull of the car so i went ahead and changed both just to be sure.
so i know for sure if i have a decat put on then my dash light will come on as it will pick up straight away that the two Lambda's are giving the same Co2 reading :)
 
I have just fitted a decat, and as soon as the engine got to temperature.....Herro its Mr eml light here !

Fitted the cat back on now, but the Cat > manifold gasket is blowing like a tw@t so the eml is back on :dapprove:
 
Ste666 said:
As far as i know if you fit a decat pipe and the light doesn't come on then it means one of the Lambda's is knackered and not reading the emissions/Co2 content right, i changed my pre cat one recently for the post cat sensor and it made a difference in the pull of the car so i went ahead and changed both just to be sure.
so i know for sure if i have a decat put on then my dash light will come on as it will pick up straight away that the two Lambda's are giving the same Co2 reading :)
Click to expand...

Really?

Well, my EML light isnt on, and the MPG rose, so cant see my lambda being shagged
 
I dont know why people get so bothered about the light on the dash, atleast if it does come on, you know why it's there!
 
plug the front one in, bung the rear one up, leave the rear one wired up and tuck it under the car somewhere. and no emissions light will come on.

not sure if you have to protect the rear sensor from the elements or not though?
 
blackpanther said:
Its a 10 min job, mine used to be on and off more times than i can remember!
(ie: put cat back on for MOT then take it back off after MOT, also sometimes got board of the loudness etc)
So not worth paying someone to do it.

Only problem you may have are the bolts rusted up, spray with WD40 and leave for 10 mins before you try.
Click to expand...

on a 172? good luck a 182 yes there simple but a 172 takes longer due to the mani - cat bolts been above the subframe and hard to get at!
 
to remove and replace my one on my 172 took around 2.5hrs, but this was my 1st ever attempt.
 
I've got to take my decat off in the very near future and replace it with the cat for mot time... Not looking forward to it, everyone on here seems to say its really awkward.
Would it be easier if i take the manifold off too or do i have to take the decat off to be able to take the manifold off?
 
James23 said:
I've got to take my decat off in the very near future and replace it with the cat for mot time... Not looking forward to it, everyone on here seems to say its really awkward.
Would it be easier if i take the manifold off too or do i have to take the decat off to be able to take the manifold off?
Click to expand...

You would have to take the front subframe off the car to get to the manifold so thats a no.
 
magh said:
You would have to take the front subframe off the car to get to the manifold so thats a no.
Click to expand...

Oh right :/ My car is a scenic though (172 lump) I think i may be able to get at the manifold bolts from above (can easily see the manifold from the engine bay)
My manifold needs to come off as i want to wrap it but im considering buying another and wrapping that and then going to kwik fit and asking them to swap it over for me..
 
I got a Janspeed decat and it has the holes to accommodate both lambda sensors on my 172 cup. It took about 500 miles and the engine warning light came on. I'm going to remove the rear one and strap it to the car and tape the hole up. Will my light now turn off? Or will it require a code reader wipe? Cheers.
 
boldswede said:
I got a Janspeed decat and it has the holes to accommodate both lambda sensors on my 172 cup. It took about 500 miles and the engine warning light came on. I'm going to remove the rear one and strap it to the car and tape the hole up. Will my light now turn off? Or will it require a code reader wipe? Cheers.
Click to expand...

Needs wiping on the OBD IIRC
 
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