Disco 1 "DeCat"

[DrRangelove]

Hi all, I have a disco 1 1995MY with the GEMS 3.9l V8. It has a rattly cat and I was wondering if anyone knows whether these can be run straight pipe without any major issues or triggering any warning lights.
Cheers
Dave

[John Boy]

The 1995 Discovery I am using had a cat on the passengers side and straight pipe on the drivers, seemed to work, but seems silly to build that way.

[DrRangelove]

Thats the same set up im running. Bit odd i agree as its then only treating half of the exhaust gasses shirley???

Are you using the exhaust for your series build or are you going custom?

Cheers
Dave

[DrRangelove]

So from the research I've done, everything points towards going straight pipe will not throw any codes as on this particular system (3.9L GEMS) the O2 sensors are pre-cat and not downstream of the cat...

I guess there's only one way to find out but if anyone has any experience with this type of mod please chime in!

Cheers

Dave

[harv]

From my experience on non rover efi's, if there are no o2 sensors downstream of the cat's, the computer doesn't know that you've removed them.

[bhoult]

It's not GEMS, but my 88 RRC is running a later model 3.9. At some point during the transition from the 3.5 to the 3.9 I performed a catectomy. There were 3 blocking up the exhaust so it breaths a lot easier. No error conditions in the 13CU managing the EFI resulted from the loss of the cats.

[DrRangelove]

Cheers guys!

"Catectomy" - Love it!