Car failed NCT emissions

Ellemc91

Hopefully someone can help me . I brought my car to the nct a few weeks ago and it failed the emissions test. Brought it to my mechanic and he suspected that it was the catalytic converter so it was replaced. Rebooked the test and brought it back but it failed again! I also used diptane both times and drove the car hard before bringing it to the test. The car was also recently serviced but a full service was carried out. Car seems to burning a lot more petrol than it used to and if the car is left running you can get a strong petrol smell from the exhaust. The car is a 98 toyota corolla.

Here are the readings:
Low Idle CO 0.91% - Above 0.50% is a FAIL
Lambda 0.99 Not between 0.97 and 1.03 PASS
High Idle CO 1.40% Above 0.30% FAIL
HC 246ppm Above 200 Fail

CathalDublin

You'll need to provide more information, what mileage, year, make, model and engine is in the car?

Ellemc91

Mileage 155.678 Miles, 98 TOYOTA COROLLA enigine 1.3 petrol

CathalDublin

Is it burning a lot of oil? High CO would generally mean poor combustion/alot of unburnt fuel, which is probably also why you have a strong smell of petrol and you are using more fuel than usual, your mechanic should be able to trouble shoot this quite easily, checking the plugs for starters.

mullingar

With high HC and high CO = running way to rich.

Was it automatically assumed it was the cat? Or did your mechanic start with the basics first? Basics would include checking the air filter, maf/map sensor, reading short/long term fuel trims, coolant temp sensor (runs rich during warm up)

BOSTIK

if you have the results from the initial test post them up too, the new CAT could be partially masking the original fault.

Ellemc91

CathalDublin wrote: »

Is it burning a lot of oil? High CO would generally mean poor combustion/alot of unburnt fuel, which is probably also why you have a strong smell of petrol and you are using more fuel than usual, your mechanic should be able to trouble shoot this quite easily, checking the plugs for starters.

It's not burning oil but it did have a small oil leak due to a seal but that was fixed. It's probably not the plugs as they were changed a few months ago when it got serviced. All plugs, filters etc. were changed when it got a full service back in January.

Ellemc91

mullingar wrote: »

With high HC and high CO = running way to rich.

Was it automatically assumed it was the cat? Or did your mechanic start with the basics first? Basics would include checking the air filter, maf/map sensor, reading short/long term fuel trims, coolant temp sensor (runs rich during warm up)

Yeah he assumed it was the cat but I had a feeling it probably wasn't that. A new cat probably wasn't needed as it looked in good condition. He has the car now and is doing a full check but he probably should have done that the first time.

Ellemc91

BOSTIK wrote: »

if you have the results from the initial test post them up too, the new CAT could be partially masking the original fault.

Here are the readings from the first test:
Low Idle CO 0.74% - Above 0.50% is a FAIL
Lambda 0.94 Not between 0.97 and 1.03 FAIL
High Idle CO 1.80% Above 0.30% FAIL
HC 396ppm Above 200 Fail

Car was waiting at least 30mins before it was tested the first time. The second time when it was tested it was only waiting about 10mins. After the cat was put in the High Idle CO and HC did reduce but it's still high.

Skatedude

Didn't the mechanic not check for diagnostic codes before doing any work? It is literally step 1 in fixing car issues liker this. Or am I missing something here?

mullingar

Skatedude wrote: »

Didn't the mechanic not check for diagnostic codes before doing any work? It is literally step 1 in fixing car issues liker this. Or am I missing something here?

Better profit margin in fitting a new unnecessary cat

mullingar

Ellemc91 wrote: »

Here are the readings from the first test:
Low Idle CO 0.74% - Above 0.50% is a FAIL
Lambda 0.94 Not between 0.97 and 1.03 FAIL
High Idle CO 1.80% Above 0.30% FAIL
HC 396ppm Above 200 Fail

Car was waiting at least 30mins before it was tested the first time. The second time when it was tested it was only waiting about 10mins. After the cat was put in the High Idle CO and HC did reduce but it's still high.

Those values scream its anything BUT the cat. It's running way way way too rich