*NCT* car failed on emissions help

[mufcboy1999]

hows things everyone.... just would be greatful if anyone a mechanic or someone with experience with this can give me a few tips or something.

my car failed nct last week on emissions because they were too high

* low idle the CO was 6.41 per cent vol... suppose to be 0.5 or less

*high idle the lambda was 0.662 per cent suppose to be between 0.97 and 1.03 per cent
*CO on the high idle was 12.8 per cent volume suppose to be 0.03 or under
*HC on the high idle was 535 ppm suppose to be 200 ppm or under

so far in my head and to the best of my knowledge i need a new cat and a new lambda sensor thats what i was told but will this do the job?..

or would i need a new back box and exhaust system aswell? i mean would i be better of just getting a whole new exhaust? if so i know where i can get a second hand 1 so it might not be too bad..

can anyone who can help me get back to me asap because iv 4 days to re-test and if i miss it by then iv to pay for full test again!! by the way the car is a 95 colt(mirage) 1.5 dohc

cheers and thanks in advanced

[call d]

where are you located?

[Darragh29]

Originally Posted by mufcboy1999

so far in my head and to the best of my knowledge i need a new cat and a new lambda sensor thats what i was told but will this do the job?..

or would i need a new back box and exhaust system aswell? i mean would i be better of just getting a whole new exhaust? if so i know where i can get a second hand 1 so it might not be too bad..

NO NO NO NO NO NO NO NO NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

You need to get it professionally diagnosed by a garage that has the necessary diagnostic equipment, namely computer diagnosis capability and an emissions tester.

You need to check all signal input sensors, (lambda, air flow, coolant temperature, air temperature), and u need to check for vacuum leaks into the inlet tract.

FORGET about replacing ANYTHING until you do the above...

Just very quickly looking at the data, this looks like a fairly serious manifold vacuum leak, possibly around the brake servo unit or manifold vacuum sensor hose. I've seen data similar to this before and the problem was a vacuum leak, the tell tale sign is the way the CO% shoots up at high idle, when inlet manifold vacuum is at its maximum... The excess O2 in the air being drawn in is picked up by the upstream lambda sensor, the ECU then horses in fuel making the air:fuel mixture far too rich, which in turn causes excess CO content in the exhaust gases...

[mickdw]

You really do need to take it to someone who knows what they are doing. Too many people assume that they must have a cat fault if they fail the emissions when in fact it could be down to a huge number of things.
If you want to go fitting a cat and then have the garage shrug their shoulders when it still fails, well go ahead. Otherwise, get a proper diagnosis.

[mufcboy1999]

cheers for the answers lads...

call d... im in waterford bud!!

darragh 29... great info will do that 2mro was actually going to buy the cat and lambda sensors 2mro but il do that 1st... and see how i get on hopefully i can do something by saturday because thats the last day for re-test.

cheers

[Darragh29]

Originally Posted by mufcboy1999

cheers for the answers lads...

call d... im in waterford bud!!

darragh 29... great info will do that 2mro was actually going to buy the cat and lambda sensors 2mro but il do that 1st... and see how i get on hopefully i can do something by saturday because thats the last day for re-test.

cheers

Jesus on your life don't go down the road of buying these parts without a proper diagnosis. I had a customer who had the exact same issue that you are having and the problem was a rubber pipe off the manifold with a crack it that was drawing in air, cost of sorting it out, 50 cent!

[mufcboy1999]

ye nice 1 bud money is not something i can be wasting at mo like most of us had it arranged to buy a cat for 50 eur 2mro and a possably exhaust but that wont happen now especcially after hearing that story 50 cent ****n in hell i would crack if i spent 120 euro for cat and exhaust! n then found out that!...just hope it isnt too much money to get fixed... the fella in nct centre said it wasnt to serious but he was foreign and hard to undestand ... cheers again bud

[Darragh29]

As always, the advice is qualified by the fact that I haven't seen the car so can't give any accurate diagnosis...

[AzureAuto]

[quote=Darragh29;63197727] the tell tale sign is the way the CO% shoots up at high idle, when inlet manifold vacuum is at its maximum... quote]

Surely at high idle the manifold vacuum would be minimal, given the throttle being open at 2000-2500 rpm?
I agree though that a vacuum leak should be checked for as the primary input to ECU for fuelling would be however the OP's car calculates load (air flow meter/manifold pressure sensor), i.e. a leak would seriously affect this calculation. Also the lambda sensor should be checked using appropriate equipment, lest that's giving false correcive values and as DAragh said, the CU is horsing in a load more fuel tahn necessary. Your values are typical of a car that is seriously overfuelling, and I'd get it chcked before any (more) damage is done to your CAT.

[Darsad]

Not too sure if your car is D jetronic or L jetronic L having an air flow meter. A car without a cat will achieve lower emisson figures than you have so dont waste your money on one just yet. If your car has an AFM then it is possible that the element is contaminated and reading incorrectly ask your mechanic to disconnect it while running it and if the figures improve it is most likely to be the cause as I have seen it on many cars. If there is no AFM Djetronic then take the other guys advice above !

[HollyEvans]

get used to it, as these regulations are tightened more and more cars are going to be forced off the road.

[samih]

In all fairness those results would be shocking even for a vehicle from 70's. My Brava with a failed cat showed CO of about 1.0 percent and HC of about 160 ppm with a lamdba value of very close to 1.0.

I would also guess the air flow meter if fitted. It's running very rich. The best plan of action is to try to get the lamdba value to as close as possible to 1.000 before even thinking of changing the cat.

[mufcboy1999]

its going in later today for a diagnosis so il update ye later...

its amazing how differnt mechanics views differ i went around to at least 10 mechanics in waterford today and nearly each one had a differnt opinion on what needs to be done and how the price verie's, it is really true there are some gangsters out there coudnt belive the prices some were charging me compared to others.

i was told by 8 out of the 10 the cat would cost around 100-150 euro(universal or mitsubishi)
the other 2 were telling it could cost up to 500 euro

i priced lambda sensors some qouted me as little as 40 euro others qouted me as much as 200 euro ...

just a huge differnce in price and prooves you have to shop around...

cheers again for the replys

[Darragh29]

Originally Posted by AzureAuto

Surely at high idle the manifold vacuum would be minimal, given the throttle being open at 2000-2500 rpm?
I agree though that a vacuum leak should be checked for as the primary input to ECU for fuelling would be however the OP's car calculates load (air flow meter/manifold pressure sensor), i.e. a leak would seriously affect this calculation. Also the lambda sensor should be checked using appropriate equipment, lest that's giving false correcive values and as DAragh said, the CU is horsing in a load more fuel tahn necessary. Your values are typical of a car that is seriously overfuelling, and I'd get it chcked before any (more) damage is done to your CAT.

I can see how you would think that the throttle being open would cause the vacuum to diminish instead of maximise, but this isn't what happens, because of the additional volume/displacement of the engine cylinders at high idle.

Remember, for that extra air volume to get inside the engine at higher idle speeds for combustion to happen, the vacuum MUST increase, the air can't just walk or wander into the combustion chamber, it has to be drawn in there by virtue of a stronger vacuum. It isn't always this simple obviously, a turbocharger compresses/pushes the air into the cylinder using compressed exhaust gases, but this is for another day...

OP, sometimes you can hear a vacuum leak if it is large enough, you can hear a subtle hiss of air which gives it away.

However often the problem is a small hairline crack, just large enough to cause what was described to me in Bolton Street DIT once as, "an illegal ingress of air into the inlet exhaust tract"... !

[Darragh29]

Originally Posted by mufcboy1999

its going in later today for a diagnosis so il update ye later...

its amazing how differnt mechanics views differ i went around to at least 10 mechanics in waterford today and nearly each one had a differnt opinion on what needs to be done and how the price verie's, it is really true there are some gangsters out there coudnt belive the prices some were charging me compared to others.

i was told by 8 out of the 10 the cat would cost around 100-150 euro(universal or mitsubishi)
the other 2 were telling it could cost up to 500 euro

i priced lambda sensors some qouted me as little as 40 euro others qouted me as much as 200 euro ...

just a huge differnce in price and prooves you have to shop around...

cheers again for the replys

The key thing you need to look out for OP when dealing with a mechanic on a diagnosis issue like this is:

(1) Do they have the equipment to diagnose a problem like this, for example computerised diagnostics equipment and emissions equipment.

(2) First thing any good mechanic will do for you is look for the obvious problems that they know can exist through their experience. As a simple example, often a perceived battery end of life problem ends up being a bad connection problem. A good mechanic will always start with simple basic checks, regardless of how many times they have seen the same symptom before.

(3) Something you cannot be too sure about in relation to (1) above, is the level of skill and experience that the mechanic has on the equipment and this comes with experience...

The rule of thumb for the good mechanic when it comes to diagnostics I think is always start at the basics and work your way from there.

Unfortunately some mechanics have not built up a good set of diagnostic skills because they were trained before this technology was around, often they are intimidated by the diagnostics technology and they get bamboozled more or less immediately when the fault doesn't fall into a certain mechanical field. I know guys who could take out an engine and put one back in again in an hour or two and it would take me a day to do it, the same guys are labelled "absolute wizards", by anyone who see's them work, but give them an emissions problem and if they cannot sort it by changing the cat and the lambda sensor, then they can't actually fix the problem, they have to hand it over to someone else.

Also, there is a big difference in parts available out there... The lambda sensor for 40 Euro was probably a universal one which I would not fit for any person no matter how short of cash they were. The 200 Euro one was probably an OEM quality part which is designed specifically for your engine as opposed to the universal one which you can try to stick into any engine...