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[Faz]

hello every one.just failed the MOT and the garage insists i should change the CAT first.Apparently they have tried to get the reading down to try and make it go through but it didn't go down enough and for the extra effort they want an xtra 50 quid.
Sofar I have spent 100 pounds for a MOT failure sheet! :-[I know all kinds of sensors and valves can effect your CO  readings  such as Lambda sensors etc. what should i change first ?Specially that I do have some kind of Ideling problem (ie fluctuating revs)and she does cut out frequently.Will this be a bigger cause of my failed emissions test than the CAT?I get no lights or warnings appearing on the Dash.Thanks for your help.

[omegaman2]

try a can of forte gas treatment £10.00 it really brings emissions into line

[Kevin Wood]

So they charged you 50 quid just to try to get the emissions through - unsuccessfully?

I think that's a bit unreasonable. The MOT test fee is 50 quid itself so they have doubled it. Did they change or adjust anything as such or just re-test after a fast idle (part of the standard test procedure anyway)? For your MOT fee you get a good 45 minutes of work so how much extra time did they spend on the emissions? If they didn't actually do anything towards diagnosis or effecting a repair I would be thinking about taking this further.

Have they checked for trouble codes in the engine ECU?

I would ensure everything else is tip top first (change air filter, oil and filter, plugs, fuel filter) and check for air leaks in the induction system. Also make sure it's not misfiring and that it gets up to temperature quickly from cold.

Kevin

[Marks DTM Calib]

As already said, there are many things that can affect emissions.

The engine needs to get to temp wuite quick or teh ecu remains in cold start enrichemnet mode and runs rich.

There needs to be no miss fires and it needs run evenly, unburnt fuel will cause an emissions failure.

The exhaust system needs to be ok.....if its not and there are loose baffles, the lambda can get confused.

So, start by checking the basics, clean the breathers and idle valve plus throttle, check the air filter and check for air leaks.

Check the plug wells for oil as well.

[x25xe]

Your idling problem and cutting out is most likely caused by the Air Idle Control valve.  It is very common on these engines.  I think that there is a guide to cleaning it on here.

Hope you manage to get a MOT without too much hassle / expense.

[x25xe]

And here is the guide:

http://www.omegaowners.com/forum/YaBB.pl?num=1194007453

It is very good and should cure this problem.

Hope it helps

[Kevin Wood]

Doh! Didn't read on to see the idling problem. That won't be helping at all, so get that sorted before even thinking about changing a cat. Garage should know better than to suggest changing a cat on a car that won't even idle properly.

Kevin

[Markjay]

...but if cleaning the ICV does not sort out the emissions, you could try:

http://www.systemproducts.com/

http://www.motorshop1.co.uk/cataclean.htm

I wouldn't hold my breath, but is seems sensible to invest £20 before changing cats....

[hotel21]

Cheapest no cost option is to speak to the friendly tester and try the test again with no air filetr in place and see what readings you get....  Would bet a nice clean filter may well solve the probs....  

[JamesV6CDX]

Cheapest no cost option is to speak to the friendly tester and try the test again with no air filetr in place and see what readings you get....  Would bet a nice clean filter may well solve the probs....  

I agree with B - but also I would be cleaning the idle valve, breathers, and possibly change the plugs to make sure you're getting good combustion.

As stated, make friends with a garage that has an emissions tester. My local rig never charges me to "test" emissions before an MOT

[Faz]

A very big thank you to each and every one of you for all the help and advice.An excellent service as usuall.I will keep you posted.

[Sir Gingerlot]

I had a similar problem the other year. Changed the CAT and it made no difference. Could you let us know what part of the omissions it failed on, this may narrow it down a bit. A couple of suggestions given to me were.

1. Air leak before the inlet. Do your heater controls make any hissing sounds. They are controlled using a vacuum pipe which can come loose and let air in.

2. Faulty EGR valve.

3. Faulty thermostate. Does your car get to temperature quickly. If running slightly cold then the management system could be putting in too much fuel which will affect emissions.

4. Any leaks on the exhaust side. This can affect the Lambada readings on the emission test.

5. A product to try is CATACLEAN. It is a fuel additive which helps clean out the whole system and reduce emissions. Saw it tested in Car Mechanic magazine with good results.

Hope this helps.

[Faz]

Cheapest no cost option is to speak to the friendly tester and try the test again with no air filetr in place and see what readings you get....  Would bet a nice clean filter may well solve the probs....  

Thanks to you   I started with the easiest option got the air filter out and banged on the floor a few times and hoovered it as well !It did the trick drove round town for 30 miles yesterday and it didn't cut out and it is idling at round 750 rpm quite happily so I invested in a new air filter.She is now running happier than she has done for ages .Having said all this there is ratelling noises comming from exhaust which it may sugest the cat broken inside?
The Emissions test failed on CO which read 0.996 on the first fast idle test and o.982 on the second  fasidle test where the max. allowed is 0.3.
The Lambda readings were 1.017 and 1.013 respectively for first and second test which is just whithin limit(max allowed is 1.03)

[Kevin Wood]

The Lambda readings were 1.017 and 1.013 respectively for first and second test which is just whithin limit

Rattling cats are never a good sign but you never know. I'd be inclined to tackle the other items mentioned in case anything else is below par and give it a bit of a run. It's running a little lean, according to the Lambda value. The engine management will take a while to "learn" new settings now you've uunblocked the air intake so it may improve. However, if it's running close to 1% CO with the Lambda within limits it does point to a duff cat, I'm afraid

Kevin

[Faz]

Cheapest no cost option is to speak to the friendly tester and try the test again with no air filetr in place and see what readings you get....  Would bet a nice clean filter may well solve the probs....  

Thanks to you   I started with the easiest option got the air filter out and banged on the floor a few times and hoovered it as well !It did the trick drove round town for 30 miles yesterday and it didn't cut out and it is idling at round 750 rpm quite happily so I invested in a new air filter.She is now running happier than she has done for ages .Having said all this there is ratelling noises comming from exhaust which it may sugest the cat broken inside?
The Emissions test failed on CO which read 0.996 on the first fast idle test and o.982 on the second  fasidle test where the max. allowed is 0.3.
The Lambda readings were 1.017 and 1.013 respectively for first and second test which is just whithin limit(max allowed is 1.03)

Oh Dear .....Its Xmas and my car has decided to kick me in the teeth for not washing the winter crap off her.She has started cutting out again!!