Before someone says it, did a search but can't find exactly what I want.

Bought car 11 months ago, fully de-catted MY95 WRX.

When I bought the car it had just been MOTd and he supplied me with the original centre pipe with cat.

Swapped the pipe over last week, MOT this morning and only thing it failed on was the CO2 emissions.

Advice please - these are the readings.


Fast Idle test:

CO - 0.62%
HC - 125ppm
Lamda - 1.03

Second Fast Idle test:

CO - 0.70%
HC - 124ppm
Lamda - 1.03

Natural Idle test:

CO - 0.69%.


Does the very high HC indicate a MAF problem, or just that the car is running rich?

Also, should I have reset the ecu after I swapped the centre pipe over?

Should I just try and get some injector cleaner, reset the ecu, go for a long blast and try it again?

Is there an easy way to just adjust mixture - or is this not possible on scoobs?

Any advice much appreciated.

 

most likely the lambda sensor.. was the cat nice a hot at the time?

Also if you have exhaust leaks it can draw air in and effect the readings.. check the joints are sealed.

 

Pretty sure no leaks, cat was not very hot - only a couple of miles before MOT.

Lamda was at the top of the allowed range - could it still be faulty?

 

It does indicate that it's running a bit rich. If you can get the lamda nearer to 1 then you may have a fighting chance of getting it through.

Also as mentioned with the centre cat only it need to be nice and hot, take it for a decent run before the MoT. Actually on thinking about it if it wasn't warm enough the ECU may still be in the cold start procedure and running it all rich for that reason.

 

Ah, ok - worth a try. I'll take it for a blast Friday and then try and get straight in for a re-test.

If it still fails when it is very hot, what would I have to do to get it through?

Change lamda/MAF?

 

could be cat' dirty try cataclean before next test should drop results drammatically,
also better as said with hot exhaust, Cataclean available now in most motor spares
shops. I know Osaka in Cardiff supply it now. Good luck m8.

 

Double check for holes, As I had the same prob which turned out to be a small hole hiding under the heat shield. Could not hear it over the noise from the blitz back box.

When you take it for re-test, Give it a good hiding first then get them to test it straight away.

Andy

 

Sounds like a plan! I'll have a look for that.

The middle cat has been in the garage for a year, so I'll try Cataclean.

Seems like v hot cat is the way to go then.

Thanks for all help!

 

personnally I don't believe all this cat cleaning stuff is neccessary..

My centre cat had been in the garage all year and when I took it out it had been used as a mouses food storage and was full of peanuts that we normally feed the birds.

I emptied and bolted it on the car and drove it for a week... the day of the test it had an hour thrash to work and an hour thrash home and straight into the mot bay and passed.

As it is rich then if there is a fault then I would replace the lambda sensor as the first thing to try.

 

Well, I also posted this question on SIDC, and someone posted a link to an older thread which had this in it:

'Any car upto 8/95 that fails the BETS test must pass a full cat test if an EXACT match is found in the emissions data.....WRX,STi RB5 and 22B 's are not listed so therefore they have to pass a noncat test (3.5 %co and 1200 ppm hc at idle). The only models listed are 2000 turbo and P1 ,the 2000 turbo is the UK model and P1 speaks for its self
It is the way the testers manual is written with the emphasis being the wording 'EXACT MATCH'.it also doesn't mention at all in the manual that a car must have a Catalytic convertor fitted as a testable item...................

So if yours is an early model and it fails the emission test then ask the tester to look in his book.


Being an MOT tester helps to understand the rules and how to flex them
'


Armed with this, went back to MOT station lunchtime, they did a re-test with non-cat settings and passed easily

Cheers Everyone for help/advice/comments

Turns out then I went through all the hassle of changing the centre cat for nowt. Next year I'll not have to bother!

Anyone want a centre-cat - don't need it now!!

 

Worth a try.. personnaly I have a UK 96..