Can you tell me how you people with fully decatted UK and Jap etc. Scoobies get through the emissions part of the MOT test? I only just scraped through and I still have my original downpipe on!

Took the MY94 WRX wagon ( with Scoobysport centre pipe and back box, std downpipe ) for its MOT today.

It JUST passed the MOT Emissions, on CO levels, think it was on fast idle.

The garage said they had had to work at it to get it through, and get the cat hot to work enough to drop the CO level to a pass.

When I reminded them it was a Jap import WRX, 1994 model and as such not liklely to be in their database then the car should be tested to non-cat spec ( much higher levels ) they then told me the databases have been updated to cover all the imports of the last few years ... and it WAS in the database now! And anyway 'cos it had a lamda sensor and cat fitted that also meant it had to be tested as a cat car.

Even if I took off the remaining cat when I swap out the downpipe, it would still be tested to cat limits! Swapping back to cat centre would not be enough they reckoned to get a pass!

Any ideas how to pass the emissions MOT with a full decat system these days? No "I know the owner" replies really wanted, as this is the MOT part of the garage I get my servicing done and who was gonna fit my downpipe! no favouritism there then!!

 

Emission numbers, for interest were :

Fast idle :
CO 0.16%
HC 34 ppm
Lamda 1.01

Natural idle:
CO 0.02%


Only other thing I can think of - I seem to have a sticking boost control solenoid which drops boost fro, 0.9 bar to about 0.4 bar ... would this mess up the figures, re: fuelling for incorrect air mass ?

 

Hi
A car with a full decat will never pass a Mot cat test.
If the car is running correct then either cat will do as long as the cat is hot.

 

Been reading up on here re: centre cats .. my WRX is jap import, I THINK it has a centre cat ( is bulging lump in centre pipe! ) but comments vary, some say early jap cars didn't have centre...

Ohh well.

 

The boost control solenoid won't affect the MOT test cos the car won't produce any boost when it's parked even if you rev the engine - you need load on the engine to get boost (i.e. the engine has to be pulling the weight of the car).

 

Just my 2 pennys worth.
I had aggro with my Type RA come mot time.
I obviously new it wasnt going to pass with the full decat, so i put back the cat in the mid section.
I then went for a "dry run" on the omissions machine, but it was obvious that the omissions still wouldnt be low enough to pass.
I then had to go back and fit the standard down pipe cat too.
A rite pain in the ****!