Another NCT emissions fail ~ help!

SuperS54

My mothers car just failed it's NCT due to emissions, I'm not around to help so hopefully some knowledgeable Boardies can.

Car is a 2005 Nissan Almera with >200K on the odometer, failed for;

Low Idle CO 6.98% (above 0.30%) MAJOR
(825 rpm) HC 224 ppm (above 0 ppm) N/A
High idle Lambda 0.81 (Not between 0.97 and 1.03) MAJOR
(2713 rpm) CO 7.09 vol% (above 0.20%) MAJOR
HC 216 ppm (above 200 ppm) MAJOR

Engine/Oil Temperature is given as 101°C.

Everything else is a pass. It's last NCT was in May 2018 and it passed everything, has covered about 5000 miles since then. Oil temp was listed as only 28°C on the last report but that seems unlikely to be accurate. The car is driven most days.

That is all the info I have, appreciate any advice!

Atlantic Dawn

I have never seen such a high fail before. Is the car burning oil, any blue smoke from the exhaust?

nanook5

SuperS54 wrote: »

My mothers car just failed it's NCT due to emissions, I'm not around to help so hopefully some knowledgeable Boardies can.

Car is a 2005 Nissan Almera with >200K on the odometer, failed for;

Low Idle CO 6.98% (above 0.30%) MAJOR
(825 rpm) HC 224 ppm (above 0 ppm) N/A
High idle Lambda 0.81 (Not between 0.97 and 1.03) MAJOR
(2713 rpm) CO 7.09 vol% (above 0.20%) MAJOR
HC 216 ppm (above 200 ppm) MAJOR

Engine/Oil Temperature is given as 101°C.

Everything else is a pass. It's last NCT was in May 2018 and it passed everything, has covered about 5000 miles since then. Oil temp was listed as only 28°C on the last report but that seems unlikely to be accurate. The car is driven most days.

That is all the info I have, appreciate any advice!

The car is running extremely rich according to the lambda value. The O2 sensor(s) are probably not working and possibly the catalytic converter gone too. There could also be a very large leak in the exhaust disrupting the O2 reading and causing it to add excessive fuel. If a code reader was plugged in and the data was read, the problem can be found pretty quickly.

SuperS54

Atlantic Dawn wrote: »

I have never seen such a high fail before. Is the car burning oil, any blue smoke from the exhaust?

Thanks. No smoke that I'm aware of, I'm not there but something like that would have been mentioned.

SuperS54

nanook5 wrote: »

The car is running extremely rich according to the lambda value. The O2 sensor(s) are probably not working and possibly the catalytic converter gone too. There could also be a very large leak in the exhaust disrupting the O2 reading and causing it to add excessive fuel. If a code reader was plugged in and the data was read, the problem can be found pretty quickly.

Thanks. She's taking it to a mechanic next week. I'm guessing replacing sensors and possibly the catalytic converter will mean the end of the road for this Almera.

greasepalm

You would think an engine light would be on dash with that high reading,possible sensors and look at exhaust + would try a bottle of cat clean before replacing cat and a good fast burn down the motorway.
Is your mother a slow driver and short distance journey drives with no motorway runs.

Field east

SuperS54 wrote: »

My mothers car just failed it's NCT due to emissions, I'm not around to help so hopefully some knowledgeable Boardies can.

Car is a 2005 Nissan Almera with >200K on the odometer, failed for;

Low Idle CO 6.98% (above 0.30%) MAJOR
(825 rpm) HC 224 ppm (above 0 ppm) N/A
High idle Lambda 0.81 (Not between 0.97 and 1.03) MAJOR
(2713 rpm) CO 7.09 vol% (above 0.20%) MAJOR
HC 216 ppm (above 200 ppm) MAJOR

Engine/Oil Temperature is given as 101°C.

Everything else is a pass. It's last NCT was in May 2018 and it passed everything, has covered about 5000 miles since then. Oil temp was listed as only 28°C on the last report but that seems unlikely to be accurate. The car is driven most days.

That is all the info I have, appreciate any advice!

I assume it’s a petrol car.
From my experience you could consider the following:-

- fit a new set of plugs

- exhaust is leaking - either a hole in it or/ and it is leaking where it is bolted onto the manifold or at one of the joints where it consists of a number of parts.

- the engine needs to be tuned. Not good if it is burning a very rich mixture
- very strongly recommended that the engine is well heated when you arrive for the test
- add a cleaning chemical to the petrol tank when filling up before the next visit. Do about 100 miles on it before the visit

Get the simple things checked out first before you start considering the more costly items.

SuperS54

greasepalm wrote: »

You would think an engine light would be on dash with that high reading,possible sensors and look at exhaust + would try a bottle of cat clean before replacing cat and a good fast burn down the motorway.
Is your mother a slow driver and short distance journey drives with no motorway runs.

Thanks. Somewhat surprised the dash is not lit up alright, she didn't mention any check lights and I would expect she would if they were lit.

Typical journey would be ~10km with some major roads, not necessarily motorway but I wouldn't consider her a slow driver, would certainly be heavy footed when accelerating although not crazy speed wise. Definitely not pottering around at 30mph.

Field east

Field east wrote: »

I assume it’s a petrol car.
From my experience you could consider the following:-

- fit a new set of plugs

- exhaust is leaking - either a hole in it or/ and it is leaking where it is bolted onto the manifold or at one of the joints where it consists of a number of parts.

- the engine needs to be tuned. Not good if it is burning a very rich mixture
- very strongly recommended that the engine is well heated when you arrive for the test
- add a cleaning chemical to the petrol tank when filling up before the next visit. Do about 100 miles on it before the visit

Get the simple things checked out first before you start considering the more costly items.

ALDI is selling the chemical at the moment.
Also As an earlier poster recommends, a good fast drive ‘down the motorway’ would be good to burn off the ‘cobwebs’ out of the engine - fairly important if the car is constantly driven at low speed and at low revs

grogi

Field east wrote: »

I assume it’s a petrol car.
From my experience you could consider the following:-

- fit a new set of plugs

- exhaust is leaking - either a hole in it or/ and it is leaking where it is bolted onto the manifold or at one of the joints where it consists of a number of parts.

- the engine needs to be tuned. Not good if it is burning a very rich mixture
- very strongly recommended that the engine is well heated when you arrive for the test
- add a cleaning chemical to the petrol tank when filling up before the next visit. Do about 100 miles on it before the visit

Get the simple things checked out first before you start considering the more costly items.

Before anything is replaced, I would check compression.

If that's fine, an air filter is a ch ap and easy fix. Then spark plugs. Next air sensors (depending what it has, might be intake manifold temperature sensor, map sensor etc), O2 sensor and cat at the end.

The fuel pressure sensor might be faulty as well, if the car has it.

chicorytip

Catalytic Converter.

chicorytip

chicorytip wrote: »

Catalytic Converter.

That won't fix fuel pouring into engine though

SuperS54

Thanks again for all the input. The car is with a local mechanic at the moment. Confirmed with home, no noticeable smoke from exhaust, no lights on dash, possibly using more fuel than before but nothing very significant if it is, oil level normal and no top ups required since the last service 8000KM previously.

Will update when the diagnosis comes back from the mechanic but given everything I'd say nnook5 is likely on the ball.

SuperS54

Car is back from the mechanic and booked in for a retest. Feedback I got third hand was a crack in an air intake pipe, leading to it running stupidly rich. Yet to be seen if all that extra fuel messed up the CAT.

greasepalm

Get a can of cataclean and add to tank as it helps to clean the cat if dirty.
Surprised mechanic did not retest emissions.

SuperS54

He tested with what equipment he had and said it looked good but couldn't guarantee it would pass the NCT test. I wasn't there so I don't know what he tested with, perhaps his equipment doesn't test the full range or is as accurate.

greasepalm

It might be borderline hence what throwing in a can of cleaner might get it down enough for a pass.

SuperS54

Hat off again to nnook5! After repairing the cracks in the inlet the car went back to the NCT and promptly failed again, pretty much the same readings as before. Mechanic checked codes again but could not find an issue, replaced the exhaust gas sensor as a precaution in case it was an intermittent fail. Car passed with flying colours on the 3rd run through the NCT.

greasepalm

Were the readings much lower on the 3rd run.

SuperS54

Yes, significantly lower.

First and second run were almost the same, below is from 1st and third comparison;

ITEM.......................FIRST RUN................THIRD RUN...........CRITERIA

Low Idle CO................6.98%

---

>0.06%...................(above 0.30%)
(825 rpm) HC.............224 ppm

---

>48ppm...................(above 0 ppm) N/A
High idle Lambda........0.81

---

>1.01......................(Not between 0.97 and 1.03)
(2713 rpm) CO ..........7.09 vol%

---

>0.11%...................(above 0.20%)
HC............................216 ppm

---

>30ppm...................(above 200 ppm)