MOT Fail - Emmisions
 

Hi all

I put my 1995 Turbo Classic through an MOT this morning and it failed on a few bits, nothing else too extreme but the worst being the emmisions. The emmsions came out at 2.73 and i believe it is meant to be around 0.90 or something close so way out!

I am unsure if my car has had the CAT removed - but would it cause it to be this far out? Also can anyone else advise what else could cause the emmisions to be sooooo bad!?

Urgent help needed please.

Thanks

David

Check the lambda sensor(oxygen sensor) is working correctly this can cause it to overfuel and in turn fail on emissions.

Agree, had the same problem, had to fit a new lambda sensor, disconnectied the battery as the engine management light had come on as well, everything then settled down and it flew through the emmisions test

Thanks for the prompt reply, any ideas how to test the sensor and if faulty where i can get another one from?

http://importcarparts.co.uk/ might be able to sort the sensor out, as regards testing, I am sure someone on here will know

Thank you, i will have a look into that, fingers crossed thats what it is!

Any thoughts about the CAT, would it fail this much without a CAT?

As long as it has the centre cat it should go through here are a couple of links for the sensor just check to see if it is the 4 or 3 wire type

http://www.ebay.co.uk/itm/3704612676...84.m1423.l2649


http://www.ebay.co.uk/itm/2607646530...84.m1423.l2649



Hope this helps. Tim

A Cat reduces CO and HC levels so depending on what you failed on this is possible, although HC levels must be <200ppm and CO below 0.3% iirc. Lambda should be between 0.97 and 1.03 which will not be affected by a cat.

Can you give us the full emissions report numbers please?

Ok this is what was printed.

Fast Idle Test: CO Level - 2.96%, HC Level - 68ppm and Lambda 0.93.
Second Fast Idle Test: Co Level - 2.73%, HC Level - 70ppm and Lambda 0.93.

It says it passed the natural idle test.

I've got a cat on my downpipe only and failed with 0.4 on emissions so I don't think 0.2 is that high

Ok all, i have just been reading about Lambda etc and apparently the location on the sensor is at the top of the downpipe on the right as your looking at it, is that correct? If so i have a plug there and not a sensor so does that mean mine is missing or could it be located somewhere else?

if you have nearly 3% CO I would say your engine is running a bit rich, closer 13.7:1 than 14.7:1.

That may be due to the Lambda sensor not adjusting the fueling, but your lambda reading is out anyway, 0.93 lambda x 14.7 (stoich) = 13.671:1 so your engine is overfueling.

If your Lambda sensor has been removed and plugged, that could account for it.

AFAIK they are located in the downpipe, near the top.

Hi, my classic only has cat on downpipe as it has been decatted in the middle, on the first run it failed emissions and on the second run once engine nice and warm it flew through!

Thanks for the info, i think the Lambda sensor may be the cheapest course of action to start with, fingers crossed it is that. I think my Lambda is located in the manifold somewhere though rather then in the downpipe as i said as it is a 1995, apparently they were located in the downpipe later on.

So frustrated, just want an MOT! :cry:

i think your lambda is in manifold iirc.

and cat needs to be up to a good working temperature before testing.

its a fcking farce anyway tbh, the reason they test ctas at idles and light loads, ie 3000rpm is because thats the only time the emissions produced by your engine will fall into parameters.

normal road driving your hardly ever getting stiochiometric air/fuel, so the cat doesnt work anyway??

the lambda is in the manifold on the drivers side(underneath) you'll see it poking out from between the heat sheilds,the one in the down pipe is the temp probe for the cat overheat system(it covers the down pipe one only).had a 94 sti that was a bit of a grey area for the emmisions but not too sure on the 95's but if you qualify for the full test you'll need to put 2 cats back in(downpipe and center)to get it officially through, even 200cell sport cats will be touch and go on a classic.good luck,
mik

Right, i think i am going to change the Lambda get the few other bits sorted that need doing then ask the test centre if they can chuck it on the emmisions test before putting it through the retest, only thing i can think of doing!

Oh, just another quick thing. The car is idling poor until its warmed, hunting for revs, i have cleaned the IACV and it no longer dies but could this also have something to do with the Lambda?

yes, probably overfueling. afaik if the lambda reading is under 100 it tells the car to add more fuel if over 100 it leans it out

Ah ok I stand corrected :notworthy

Def the lambda sensor mate if its idleing poorly till warmed up. If you only give a slight blip on the throttle does the engine start to stall? If so its just sending too much fuel common fault happened on mine a few years back.

Can someone advise exactly where the lambda is? Is it at the bottom of the engine on the manifold to the left as you look down on the drivers side?

Exact same symptoms mate! I will order a sensor!

Can anyone advise if this will fit mine, i have a 3 wire sensor located in the manifold NOT downpipe - http://www.ebay.co.uk/itm/NEW-Oxygen...ht_7634wt_1151

Bump.