cefski

Took the car for an MOT earlier - a 00MY uk turbo, with de-cat downpipe. Had hoped that it would pass emissions with only the centre cat in place. Did it bollox.

Fast idle test for CO #1 - Should be less than 0.30%. Came back at 1.47%

Fast Idle test for CO #2 - came back as 1.75%

Natural idle test for CO - should be less than 0.50%. Came back as three-point-fookin-nine-six per cent - EIGHT TIMES above the legal limit

That'll be a fail, then

Car had been thouroughly warmed up, too.

Has anyone here passed emissions with just a centre cat? Catted downpipe is now back in place for a re-test on Monday.

Kev

tallsteve

Had a similar problem with my Legacy Turbo, all cats still in place.. Turns out that the high CO2 was caused by a dodgy lambda sensor - might be worth checking!

Good luck with the MOT!

seanks

Exactly same thing just happened to me. Took car to a dealership in Widnes with standard exhaust in boot (heard they were sympathetic when came to decats), had told them it was fully-decatted, got told they had got full-dects through so was hopefull, guess what, it failed.

They said they'd have to put a cat back on (I surmised it was the centre but didn't ask, my fault), one hour £62 to do!
So finally got a call Saturday morning, passed!
How much £180 inc MoT charge!!! They had replaced the downpipe cat and it had taken them two hours!!
My lad was hugely disappointed when we picked it up and the exhaust growl had virtually disappeared!
Won't be getting caught like that again.

How easy is it to change the downpipe, anyone done this themselves?
Also, for the time being as the cars been remapped with full decat, is having the catted downpipe in going to cause any problems?
cheers

Beastie

iTrader: (2)

mine failed cause MAF was on way out. fitted new MAF and passed easily.

seanks

Beastie
Was that with a full-decat?
Mines a MY99, new models maybe better?

cefski

I might have a go at swapping the pipes round later in the week, as once the heatshields are dispensed with, it doesn't look too difficult (note to self - remember to disconnect the lambda sensor!!!) . Brother in law has a pit in his garage which may come in handy, as i think that the downpipe can only be manouvered into position (or out of position, for that matter) from under the car.

I might invest in having a twin-cat centre section made up sometime this year, purely for MOT purposes. Centres are way, way easier to swap over than d'pipes.

Car is booked in for a re-test tomorrow morning. Presuming the lambda sensor is ok, there shouldn't be any probs. How much for a new sensor, btw???

Kev

cefski

Failed again

Must me the lambda sensor. I HOPE it's the lambda sensor.

Anyone have any idea how much these things cost???

Cheers

Kev

AvalancheS8

My '97 passed no bother with only the centre in, I don't have the sheet to hand but the results were spot on, low emissions, no problems at all, So it should be possible if everything is healthy.

ozzy

If the centre cat is in good condition it should pass easily. Mine has done it twice.

New Lambda is around £120 for an original Subaru one. You can get universal ones for a fraction of this but you'd need to modify the connection.

Stefan

ozzy

Kev,

Here is my results. Car is a MY99 RB5.

First is a PASS with centre cat only.



Second is with a full de-cat (no hope in hell of passing).



Stefan

Beastie

iTrader: (2)

Seanks mine is a MY99 with cat in downpipe.

aggs

My MY2000 classic passed with just the centre cat.
Could be another problem??

cefski

Thanks very much for the info, chaps, particularly for ozzy's scanned emissions results. Definitely something wrong with mine if ozzy's figures are that low with a full de-cat.

Managed to source a nearly new lambda sensor from glenburgie (CLICKY), for about £40 +vat and p&p, so we'll give that a go. Should be here by the weekend.

Once again, cheers.

Kev

ALi-B

iTrader: (1)

If your lambda sensor is gone...I'd expect to see a slightly higher than norm HC level (unburnt fuel)
And also your lambda reading (Air/fuel ratio) will be out too and also be unstable (lean one minute, rich the next)

(refer to ozzy's helpful printouts fr what you "should see" )

cefski

Yup - all that matches my results. HC was slightly up for all twelve tests (eight fast idle tests, four natural idle tests), but still way below the max permissible levels. The lambda readings were almost always slightly lower than acceptable levels (10 out of 12 times), but never higher.

kev

Jolly Green Monster

iTrader: (4)

Would be a good idea to reset the ecu once the new sensor is in, otherwise it MIGHT take a little time to readjust the fueling to get the emissions correct, depending on the year of the car.

My Link ECU mapped by me just passed with a centre cat fitted..
Going back hopefully friday with full decat to see how far out it is without the cat.
Mine only did fast idle though.. the natural idle test was done at the same (2800) rpm and the print out says RPM not checked. I doubt it would idle lean enough on the bigger injectors as they seem a b1tch to get it idling smoothly without going slightly rich.

I'll try and get a print out for decat (have the pass test print out already) and will scan them both etc..

ALi-B

iTrader: (1)

That would suggest the engine is running slightly rich

The HC limit is not very stringent, so a bad running engine can easily pass the HC emissions, but the reading does help point to what is causing the problem . Anything approaching 60+ppm indicates things aren't ideal.

The Lambda being consistently low means the engine is always running rich. (a 0.2 difference, although within the limit can make a quite a big difference to the CO).

So, I would suggest the oxygen sensor is the most likely curlprit (although there is a slight possibility for a coolant temp sensor fault - but I very much doubt that).

cefski

Once again, thanks for sharing your wisdom, chaps.

Just changed the lambda sensor (for a nearly new one) and done the full ecu reset procedure. CEL didn't show any fault codes and started flashing steadily almost as soon as i moved the car, so I presume all is well. Re-test tomorrow am.

Question for you mech-heads... Would a dodgy lambda sensor cause the engine to occasionally hunt for a few seconds when bringing the car to a stop? Noticed this over the past couple of weeks - engine speed would dip to roughly 500 or 600 rpm at idle when warm, but wouldn't do it more than twice before settling at the normal 800rpm.

Just a thought.

Cheers again.

kev

Jolly Green Monster

iTrader: (4)

the symthoms you describe with regard to idle sounds more like a failing MAF but if it is not any worse since the ecu reset then hopefully this is not the case.. if it was very rich due to faulty lambda sensor then yes it could cause this to happen but less likely.

ozzy

Although this is a classic symptom of a failed MAF, it's also the very same symptoms as I experienced when my Lambda sensor failed on my car. So yes is the answer.

Stefan

cefski

Who can see me dancing???

the car passed easily with a replacement o2 sensor and a re-set ecu. For fast idle, CO came back as 0.00% (as opposed to the worst result of 4.90%), HC as 001 (as opposed to the worst result of 029) and lambda as 1.01 (worst was 0.87).

CO at natural idle was 0.30%. (Both cats in place for all of these tests)

The hunting problem also seems to have been cured, though I'll change the MAF at next service in a couple of weeks just to be sure.

Pints all round if you're ever over this way, fellas.

Cheers

Kev

Jolly Green Monster

iTrader: (4)

Glad it passed

cefski

I feel like taking the day off work to celebrate

kev