Does decat affect how the engine runs?

1. mrrwill Infrequent Poster Joined: Sep 2014 Posts: 234

   #1 25th July 2015, 09:36

   I'm just wondering if someone can shed some light on how a decat affects the running of the engine. Ive had a decat manifold on my 52 reg vtr for about 6 months and just wedged the second lambda sensor between the manifold pipes as I heard they need to be hot to operate. I didnt fit it into the second hole on the manifold as I didn't want my engine management light on all the time.
   There have been no changes in the way the engine runs from what I can tell, but the second lamba reads clean air. If it was in the exhaust behind the cat it would still read some crap but eco friendly crap.
   Is the post cat sensor just there to check that the cat is working and therefore not affecting the engines running? I.e fueling or whatever..
   the exhaust fumes do smell fumy this is just becaise it's decat I guess isnt it?
   
   Cheers
2. white_vts_boy Established Member Joined: Dec 2007 Middlesbrough Posts: 1147 Saxo vts

   #2 25th July 2015, 15:22

   Couldn't say on a Vtr but on my vts all that ever happened was it put the engine managment light on but the car had always ran fine
3. forbessid Frequent Poster Joined: Jun 2006 Cheshire Posts: 621 mk2 Icelandic Vts.

   #3 27th July 2015, 07:24

   If you dont connect the lambda then you will need a sleeve from kam racing to put onto it so it tricks the ecu into thinking it's connected up.
4. Manu Saxperience Addict Joined: Dec 2009 Posts: 11714 A6 Le Mans tuned/A3 TFSI tuned

   #4 27th July 2015, 10:51

   Quote:

   and therefore not affecting the engines running? I.e fueling or whatever..

   it will affect your petrol consumption.
   
   

   Quote:

   the exhaust fumes do smell fumy this is just becaise it's decat I guess isnt it?

   It's the smell of unburnt petrol. Every time I drive behind a decatted car, I can smell it
5. mrrwill Infrequent Poster Joined: Sep 2014 Posts: 234

   #5 28th July 2015, 15:56

   Oh i see, I might buy one. Mine is jist wedge between the manifold pipes. Will the engine be running lean? I hear this can cause problems?
6. user_20080 Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.

   #6 28th July 2015, 17:13

   Quote:

   Originally Posted by mrrwill Oh i see, I might buy one. Mine is jist wedge between the manifold pipes. Will the engine be running lean? I hear this can cause problems?

   No the engine will be running rich.
7. mrrwill Infrequent Poster Joined: Sep 2014 Posts: 234

   #7 28th July 2015, 17:35

   Oh, sorry if thats too much fuel, thats what I meant. Is that bad? And do these sleeves sort that out? Read something somewhere about drilling a small hole in them or something
8. user_20080 Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.

   #8 28th July 2015, 18:09

   The sleeve just allows the lambda sensor to read clean air,in doing so the eml doesn't come on.
9. mrrwill Infrequent Poster Joined: Sep 2014 Posts: 234

   #9 28th July 2015, 19:45

   Ooh, mine isnt on as ive got a plug in the manifold.. thought the sensor had to be kept hot or something though