S4 De-cat?

[disley]

Any issues with going for a complete de-cat on an s4
other than it will not pass an m.o.t, what about lambadas, egt sensors etc
will the fact that theres no cats cause problems with these,
I was thinking of purchasing one of them ebay systems

 

[Siena]

My advice:

Keep the catalysts. Or replace with 200 cell sport CATS.

Why are you thinking of deleting them, out of interest?

 

[aragorn]

I think the common consensus is that the two precats in the turbo elbows can be removed for a reasonable performance increase.

if you remove them all, and your car has 4 lambdas, you will generate a fault code.

If you remove only the precats and you car has 4 lambdas you can move the second lambda after the main cat to stop any faults.

if your car has 2 lambdas you wont have any problems

I'd go with the Ebay downpipes, but fit a pair of sportcats under the car where the main cats usually sit.

 

[Blue_Thunder]

EGT's are in the manifolds, so de-catting won't affect those at all.

The S4 has only 2 lambdas (RS4 has 4). Assuming you are getting a remap at the same time to make the de-cat worthwhile, the tuner can alter the map so that fault codes won't be thrown.

Expect your car to sound fairly raspy with no cats though.

 

[aragorn]

i thaught later S4's had 4 lambdas and early ones had 2?

I've defo seen articles on the net on moving the secondary lambda sensors on S4's before...

 

[stapo69]

I thought the same, US S4s def have all 4. Funnily enough I fitted some LAbree downpipes a week or 2 back, before I was getting a fault on one lambda every so often even after replacing it twice, but now nothing! Result! I concluded maybe a knackered precat?

 

[andybnwc]

At present i run no cats and one small back box , its raspy and horrible at certain revs , i still need to put my new system on so see what it sounds like with 2 boxes.

Later s4s have 4 and vast performance do some extended ones ready for relocation .

 

[disley]

thanks for the info folks,
just thought a de cat and a remap would be a good performance increase but maybe as aragorn sugested, maybe a set of downpipes and sportscats aswell is the way to go or even cheaper a cat back and gutted precats,
My car is a 2000 X so i take it it probably has 4 lambadas?
surely performance would be greater with no cats at all?