# Can you map a skyline to pass an MOT Emissions test without a cat?



## Mwohaaahaahaa (Feb 19, 2010)

Hello,

I was wondering if it is possible to map a skyline to pass an emissions MOT test without a catalytic converter. I know if such a map was possible that it would probably not generate much power but that is not the point.

What are you thoughts?


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## Wade (Jul 31, 2008)

I know this isnt the answer but just put a cat on mate and rip it off afterwards.

Some places even let you leave them in the boot :thumbsup:


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## Mwohaaahaahaa (Feb 19, 2010)

True, but I believe if you get pulled you can be made to do an emissions test on the spot (not 100% sure if that is true, but that's what I have heard) If this is the case than it's not going to be easy to put the CAT back on even it if is in the boot 

The ECU I plan on getting can hold multiple maps and you can switch between then at the touch of a button. So the other map would be my main one and this one for emergencies or MOTs


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## Rain (Apr 8, 2006)

Run a map for street using the cats, and one for track without? not like you can make full use of any car on UK roads as it is, so whats the little bit of difference the de-cat would gain you.


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## mambastu (Feb 13, 2002)

what Skyline is it ? 32, 33, 34 ?


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## rage33 (Oct 12, 2011)

They cant do on the spot tests. The only way they would suspect somethings not right with the exhaust is if its too loud. The law states that an exhaust cant be louder than standard but how are they gona know that? These cars are expected to be loud.

If they do want it tested they will most probably give you a 7 day wonder where you have to produce documents to your local police station with in 7 days


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## jabran200 (Sep 5, 2005)

It is very easy to make a gtr pass emissions which is just the very basic test. I did it on my GTR and it passed no problem on the same power map as to be honest any map that does not give you good economy on cruise and power in the same map is a crap map.


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## mattysupra (Oct 31, 2008)

rage33 said:


> They cant do on the spot tests. The only way they would suspect somethings not right with the exhaust is if its too loud. The law states that an exhaust cant be louder than standard but how are they gona know that? These cars are expected to be loud.
> 
> If they do want it tested they will most probably give you a 7 day wonder where you have to produce documents to your local police station with in 7 days



O yes they can. They can impound your car if the cats are missing. If you fail the emission test and the CAT is present then they will normally give you a certain amount of time to repair the issue. 

But if the CAT is missing in the first place you are in trouble.


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## mattysupra (Oct 31, 2008)

I believe it is possible to do a map to pass emission tests with the CAT missing. but form what i understand the car wont be drivable. It will be more a flick teh map over if you get pulled. 


However. Just fit a sports CAT and solve all issues.


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## jabran200 (Sep 5, 2005)

mattysupra said:


> I believe it is possible to do a map to pass emission tests with the CAT missing. but form what i understand the car wont be drivable. It will be more a flick teh map over if you get pulled.
> 
> 
> However. Just fit a sports CAT and solve all issues.


No, it can be done as emissions on a gtr is very basic test unless you have an r34 then it may be a bit of an issue.


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## Min-e (Sep 23, 2009)

My 32 passed the emissions test with flying colours without a CAT and running 346bhp at the hubs on 0.95bar with a Link G4.

James


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## GOGS 2 (Jun 21, 2009)

if your car is made before 1993 you dont need a cat to pass emission test. so no problem with a decat on older r32


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## Mwohaaahaahaa (Feb 19, 2010)

Min-e said:


> My 32 passed the emissions test with flying colours without a CAT and running 346bhp at the hubs on 0.95bar with a Link G4.
> 
> James


Depending upon the year of your r32 you may not need a cat to pass. the law only applies to car from 1991 (or something round then) and onwards. anything older than that I don't even need to pass an emissions test.

With Regards to getting your car impounded for not having a CAT I believe that but only because it wouldn't pass an emission test. If you could prove you could pass the test without the CAT then they would have no right to take your car with or without a CAT. (If you have more up to date info on this please correct me)

I would go for a sports cat but even then you may not pass the test. they are not that good and I like it when my car backfires and a little flame comes out the back. If I put a cat on that will not happen any more.


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## Mwohaaahaahaa (Feb 19, 2010)

mambastu said:


> what Skyline is it ? 32, 33, 34 ?


Its an r33 gtr. The ecu I am thinking of getting is the Haltech Platinum sport 2000. which i believe is the only one in the Haltech range with switch-able maps. Other wise I would have gone for the plug in version.


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## infamous_t (Jul 9, 2007)

Have been told it can be done comfortably if your running e85 with some time spent on the tune.
Put a cat with a straight pipe on the inside and everyone's happy


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## Mwohaaahaahaa (Feb 19, 2010)

infamous_t said:


> Have been told it can be done comfortably if your running e85 with some time spent on the tune.
> Put a cat with a straight pipe on the inside and everyone's happy


Can you get a CAT with a straight pipe through it?


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## rage33 (Oct 12, 2011)

GOGS 2 said:


> if your car is made before 1993 you dont need a cat to pass emission test. so no problem with a decat on older r32


I thouth it was 1991. And that only applies to uk cars. 
As its an import its actually '95. So if its pre then you will be ok with out one.


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## rage33 (Oct 12, 2011)

What reg is your Skyline?


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## ragt20 (Jun 28, 2003)

not so simple when you can't even fit a sports or standard cat


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## infamous_t (Jul 9, 2007)

Mwohaaahaahaa said:


> Can you get a CAT with a straight pipe through it?


Yes. 
Or you can can make one, much better than hacking at a cat with a broomstick.


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## Mwohaaahaahaa (Feb 19, 2010)

rage33 said:


> What reg is your Skyline?


Mine is a 1995 r33. So does that mean I don't need a CAT or would it have to have been 1994?


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## LongRat (Apr 9, 2012)

Here is a useful guide to find out what emissions testing your car legally requires:

pic100.picturetrail.com/VOL660/2777486/13836344/404506761.jpg

I guess you have to copy and post the URL (with an http double backslash in front) as I don't have enough posts to post a link.


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## gtr R33 lee (Nov 11, 2004)

I know its not the same but had a 1998 306 diesel once, after replacing part of the exhaust and leaving the cat out omissions were lower than when the cat was present!


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## Cris (Sep 17, 2007)

One thing to bear in mind is that the car must pass the level which is recorded for the car. As R32 were not officially imported there are no levels which the car must meet. Obviously if it's pre mid '92 then the cat isn't needed anyway.

I have never even had anyone ask about the cat at MOT time. And given that they have complained about other things which are perfectly fine...


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