Benefits Of Decat-Ing A 1Gfe

[MKT222]

i'd like to say hi to all,i just joined LOC,

if i removed the 2 catalytic on my is200,will i get a check engine light?...if so,what can i do to prevent the CEL?

thanks in advance

[ACLex]

i'd like to say hi to all,i just joined LOC,

if i removed the 2 catalytic on my is200,will i get a check engine light?...if so,what can i do to prevent the CEL?

thanks in advance

First of all I believe the MOT laws are changing from March this year and they state that all cars originally fitted with a catalytic converter must have them fitted for the test :(

If you really want to remove them you can buy a complete de-cat manifold on eBay and you will need spacers for the O2 sensors.

Andy

[fjcfarrar]

i'd like to say hi to all,i just joined LOC,

if i removed the 2 catalytic on my is200,will i get a check engine light?...if so,what can i do to prevent the CEL?

thanks in advance

Why do you want to do this? Unless the Cats are faulty/clogged, you will not get a power increase that you will notice.

[MKT222]

my plans are just install an open type air filter and de-cat the exhaust just to lessen the load a little bit for the engine

[steve2006]

I wouldn't bother, cost of converting outweighs the insignificant benefits plus an MOT fail.

[MKT222]

ok,thanks guys,i guess ill just leave it stock

[ormi]

so far every one is wrong on the mot fail part.......but it depends on the cats you mean to what affect it has on the mot the pre cats you can do away with but the main cat under the car needs to be their...

theirs 2 pre cats which are part of the manifold which would involve a replacment manifold(you will get no fault lights doing this)i have one fitted....slightly better throttle response and a change in exhaust note

the main cat you will need a 02 sim and it will fail an mot....not much gain at all so little its not worth doing

[ACLex]

so far every one is wrong on the mot fail part.......but it depends on the cats you mean to what affect it has on the mot the pre cats you can do away with but the main cat under the car needs to be their...

OK, so is a pre-cat a cat or not?

Andy

[fjcfarrar]

Later this year, the MOT is set to include a requirement for all OEM warning lights to be functional as shown by the switch - on sequence, and none to light erroneously. This means you can't now just take a bulb out.

I don't know how rigorously this will be applied, bearing in mind the short time allowed for the whole test.

[noby76]

Mate just get an IS300 2JZ-GE engine and drop a turbo in if the 210bhp stock is not enough that will solve your problem. the only way to gain power is 1. a bigger cubic capacity (engine) or 2. forced air (turbo). decating a car will not increase power.

[steve2006]

Later this year, the MOT is set to include a requirement for all OEM warning lights to be functional as shown by the switch - on sequence, and none to light erroneously. This means you can't now just take a bulb out.

I don't know how rigorously this will be applied, bearing in mind the short time allowed for the whole test.

I read somewhere (can't remember) that for a period of time after the introduction of the new checks if there is a problem they will be an advisory and after the time period has expired they will be fail items.

[ormi]

only the main cat comes into this the pre cat doesnt..

also the engine management light will NOT be coming in to the mot p/s will as will the air bag..

since ive been a tester you cant remove bulbs to get through the mot as it tells you on the vt40 whats fitted to the car and how long the lights stay on for..ive been testing around 5 years

the pre cat isnt classed as a cat when it comes to mot.....and thats from our vosa boy..as stated i am a mot tester hence the reason i get to talk to vosa

[durg]

the pre cat isnt classed as a cat when it comes to mot.....and thats from our vosa boy..as stated i am a mot tester hence the reason i get to talk to vosa

I'm intrigued with the comment that the pre-cat isn't classed at a cat in the MOT test. Surely so long as the tail pipe emissions meet the right level (ie. they are below the limit) it doesn't matter if the front or the rear catalyst is doing the work?

Also a question - does the IS200 have five O2 sensors as the IS300 does?

[Twins1984]

i've got 2 decat pipes fitted

They look like cats so shouldn't be a problem with MOT and increase exhaust gas flow so you will notice increased torque in lower rpms and better throttle response.

I did notice a difference, now need a decent air intake kit :)

[ormi]

the pre cat isnt classed as a cat when it comes to mot.....and thats from our vosa boy..as stated i am a mot tester hence the reason i get to talk to vosa

I'm intrigued with the comment that the pre-cat isn't classed at a cat in the MOT test. Surely so long as the tail pipe emissions meet the right level (ie. they are below the limit) it doesn't matter if the front or the rear catalyst is doing the work?

Also a question - does the IS200 have five O2 sensors as the IS300 does?

right i knew id get silly questions.......

if you remove the main cat it will fail as the main cat has to be seen also the main cat does 95% of the cleaning

you remove the main cat and keep the pre cats it will fail the emissions....

remove the precats and keep the main cat it will pass the emissions...

it has 3 sensors

the mot wording

Reason for Rejection

1. An exhaust system not adequately supported.
   

1. A major leak of exhaust gases from any part of the system.
   

1. A catalytic converter missing where one was fitted as standard
   

[durg]

Thanks for the reply - my question wasn't intended to be a silly one! I was just intrigued in how it works in terms of the MOT test. The design of the catalyst system is carefully planned. The close coupled catalyst (often referred to as the "pre-cat") performs as big a role as a catalyst as the underfloor (or "main" catalyst). The close coupled catalysts are designed to deal with the emissions coming from the engine when the engine is first turned on and although they are smaller than the underfloor catalyst they contain much more precious metal and are therefore more active. They will convert about 90% of the hydrocarbon and carbon monoxide emissions coming from the engine and a significant level of NOx. The second catalyst is there primarily to deal with the NOx emissions generated by the engine during higher speed driving conditions where more catalyst volume is required. Yes a hot underfloor catalyst is very active but it is not the only active component fitted.

My point being - on the MOT idle and elevated idle test the close coupled catalyst on its own (if in good condition) should be capable of dealing with emissions and bringing them under the threshold required to pass the test, and this is why I asked the question about the specific details of the test requirement regarding which brick is being considered during the test.

I work for one of the worlds largest (if not the largest) suppliers of catalytic converters and I'm currently running some advanced engineering projects for Lexus so I do have quite a good understanding of how these things work.

Thanks, Dave