Hi guys

 

Can anyone tell me if there ia any advantage by removing the de-cats and does it improve performence, also would there be a problem with mot ?

 

Cheerz

 

Chris

no problem with mot. can increase performance but depending on the condition of your turbos it can cause the seals to go.

When you say "can" improve, is it marginal e.g. 5hp or ? Also been looking into this and wondering if I'm going to get stung on the MOT if I remove the pre-cat's and de-cat it at the same time?

 

p.s. is this going to make it real noisy too?

Personally wouldn't take the cats off unless you have new/good known turbos. It will imrpove performance, but that depends on the condition of the engine and turbos.

Personally wouldn't take the cats off unless you have new/good known turbos. It will imrpove performance, but that depends on the condition of the engine and turbos.

 

What he said.

as said above you'll grab a few ponies from it Chris, but the benefits will grow as you run higher and higher boost - they'll become less of a bottleneck.

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Edited October 6, 200916 yr by Daves_Zed

As long as your is pre-August '92 you should be OK, as the Cat laws don't apply!

 

That's not strictly true...it's pre '96 (not sure of the month though). It'll still have to pass the emissions test however.

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Edited October 6, 200916 yr by Daves_Zed

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Edited October 6, 200916 yr by Daves_Zed

the 300zx does not require cats to be fitted and does not need to pass a cat test of any type because it is one of the few exceptions as it is not listed in the exhaust emissions database. Only cars after 95 must have cats fitted and must undergo a cat test.The proper emision test for a pre 95 z is 3.5% co and 1200ppm hydrocarbons tested at idle wether it has cats fitted or not.As for failing because the cats themselves are missing, mot stations have no reference data refering to what exhausts are fitted , so most testers would not have anyway of knowing if cats were fitted originaly and could only advise the fact that a cat might be missing, would be different at a nissan dealership or a z specialist though.

also dave zeds info is from northern ireland test info which is different to uk test.

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Edited October 6, 200916 yr by Daves_Zed

Im an mot examiner mate what you have posted is basicaly correct but yo dont have access to all the required information ie exhaust emissions database, car being tested must be listed in the database to require a cat test and the 300zx is not listed so does not get a cat test, the 300zx up to aug 95 not sure on exact date but definately late 95 must be tested to the older non cat emissions test ie 3.5% co and 1200ppm ydrocarbons at natural idle. from 95 on all cars must pass a cat test and would require a cat to be fitted to do so.all my info comes direct from vosa via the vts device at the testing station.

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Edited October 6, 200916 yr by Daves_Zed

Hi guys

 

Can anyone tell me if there ia any advantage by removing the de-cats and does it improve performence, also would there be a problem with mot ?

 

Cheerz

 

Chris

 

No need for all the debate.

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Old 3rd January 2004, 09:22 #1

Paul C

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Lightbulb MOT emissions test on a zed (cat test)

asked many times when decatting, so heres the score:

 

any vehicle registered from 1 august 1992 has to go through the MOT BET test (Basic Emission Test), the limits are:

Fast Idle

CO

HC

Lambda between 0.97 and 1.03

 

Idle test

CO

 

if the vehicle does not meet these figures (decatted vehicles may well NOT) the the test proceeds on to a more specific test.

 

if the vehicle is between 1 aug 1992 & 31 july 1995 and an exact match is found in the Emission database, then a CAT test is done using the vehicle specific details

 

However, the Z32 is NOT in the emissions database, this means a NON-CAT TEST is carried out using the same values as pre 92 cars

 

Non Cat Test

CO

HC

 

as long as everything is running ok then even De-Catted cars should pass this!

 

if you're lucky enough to own a 1 Aug 1995 on Zed then a default Cat test will apply, which you will prob fail if you De-Cat!