Twin Lambda - Saxperience

Alex_3589 · 7th March 2008, 23:54

VTR's from 2001 onwards have twin lambda sensors; so what i want to know is;
-how do these work? do both readings from the sensors have to be the same for the car to run properly?
-is there one sensor before the cat (plugged into the manifold) and one under the car, after the cat?

I am intending to turbo my VTR, and want to run a sport cat either on the downpipe or under the car after the downpipe;
-would one sensor plug into this downpipe; http://www.dp-engineering.nl/EN/prod...DP_Blister.php
then the other plug in after a sport cat under the car?

Mark51^p · 8th March 2008, 00:07

the first sensor measures the amount of harmful gasses before they enter the cat and the one after the cat measures the same gases after they have been through the cat. the level of harmfull gases that have passed through the cat is reduced.

you dont really need the second one as people de-cat their cars to allow a faster flow of gases through the exhaust system as the cat is very restrictive. you can get a sleve from GMC that the second lamba sensor fits into to trick it into thinking it reading safe readings for the amount of harmful gases.
you should be able to get a exhaust system (probs a BTB if you can find one) that allows you to put your cat back in for MOT time. if you engine is setup proberly then it should still run ok with the cat on for a short amount of time (long enough for it to pass the emissions test for your MOT)

Alex_3589 · 8th March 2008, 00:15

cheers mate, i want to run a sport cat under the car after the downpipe;
will it pass the MOT, obviously with the fuelling right?

Mark51^p · 8th March 2008, 00:23

^^ yes it will do but imo id run a 2.5" ystem with the option for you to add the cat in when it comes to MOT time

Alex_3589 · 8th March 2008, 00:27

yea, im guna get a 2.5 inch system built custom by a place called AAS soon.
So its going to be the dp engineering manifold, gt25 turbo, the dp downpipe, a sport cat then the custom system...
do you think having the 2.5 inch system on a standard car apart from a filter for a while will lose me a lot of power?

Mark51^p · 8th March 2008, 01:27

some think it does and some think it doesnt. becasue i have not had a 2.5 system on mine i cant comment. i picked up a BTB from GT3 the other week and he said that he thought he lost power becasue of the large bore but other people disagree

AXracing · 8th March 2008, 08:25

As long as you still have a cat yes. In the early 90s all cars had to pass the new CAT test. But if you could pass it with out the cat that was fine. However they later changed the reg early 2000 to force to to have a cat. So the only way to get a legal MOT is to still run a cat.