QP Cats

[AndyG]

Can anybody tell me if I will have any running issues if I remove my primary cats on my QP, as the n/s bank has started to rattle.

Andy


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[gingeh721]

Yes. Big ones. The primary cats performance are measured by 4 lambda (oxygen) sensors. 2 per bank, 1 pre cat sensor and 1 post car sensor. The Ecu will see that the cat is not working correctly and display cell codes 4021 & 4031 in addition to putting the car into limp home mode after a number of cel cycles.

The car will pass mot emissions due to the large secondary cats but your engine management will eventually shut down.

Search my last post - 4200 - 200 cell cats fitted.

Regards.

 

[gingeh721]

Also see post

ncsle - Strange Exhaust Noise

 

[AndyG]

Yes I thought that maybe the case, if you replace both primary and secondary cats with 200 cell units what position do the sensors need to be ?

Andy


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[gingeh721]

Sports cats come with a boss on them so they just relocate the second sensors to where your secondary ones were. No cutting needed. The wiring is really long and they just undo a couple of clips and screw them in.

 

[gingeh721]

I got my primary cats gutted as it was cheap and easy (they were barely even there and had disintegrated). They just cut a section off the top of the primary cats, gutted them and welded it back up. This was done on the upper half of the cats for presentation and it looks less messed with for future mots. Not that this would be a problem as it still passes emissions.

The secondary cats were then cut off and the sports cats welded in place. The lambda wiring was then unclipped from it's securing brackets and then just screwed in to the new holes on the sports cats. It took the garage about 3.5-4 hrs.