Advice needed please. Failed NCT

bobbyss

You could write down what I know about cars on the back of a stamp so excuse my total ignorance.

Would be very grateful for advice on the following as I need to pass the retest.

Failed NCT. 3 year old car Qashqai. (I think that holds 55 litres approx?) Emissions were outside the limit. The garage told me there was no issues with the exhaust so it was probably my low milage. He suggested using Dipotane. Never heard about this before. So I have been told different things about how to use this so I am very confused.

Are the following correct?

A. The mechanic at the garage said: When you tank is almost empty put in a 1/4 of the Dipotane. Then fill up. Go for a long, long drive on the motorway. When you do the retest just ensure that the Dipotane has gone out of the system as this may influence the reading at the test.

Question: If I have the retest in about three weeks do I just use the 1/4 bottle of Dipotane just once and that is it? Or do I need to use all the bottle and take it o frequent motorway trips?

Question: He said go on the motorway at motorway speed. He suggested a long trip. But someone else said do the motorway drive in 4th gear but on a shorter journey at 80kph. Or maybe both suggestions are correct?

(I would have thought driving in a low gear at a fast speed would damage a car? 4th gear at 80kph seems to be pushing things a lot. Is that not like driving at 60kph in 1st gear? )

He also said not to worry if you get the ratio wrong with the Dipotane as it would not damage the car.

Yet another person said:

take it on a long drive the day of the NCT retest. (Would this be after I have filed up again with no Dipotane in the system or just a regular motorway drive?)

have it in idle as long as you can before the NCT fellow takes the car into the centre.

So my query really is this. I have a retest in three weeks. I just got the Dipotane. What should I be doing between now and then? Do I need to use all the Dipotane ? Frequent Motorway trips? In normal or in 4th gear? Would it be a good idea to go on the motorway the day of the retest? It seems important to have the engine hot when tested???

By the way the day i took it to the test was freezing and I was the first there at 7am.

Many thanks in advance for any advice but please note my complete ignorance in car matters.

User1998

Theres no need to overthink it, just follow the instructions on the bottle. It sounds like you don’t drive your car hard enough. 80kph in 4th gear is completely safe. Drive the car using the entire rev range and don’t change gears early. Make sure you get the engine completely hot for the re test and drive the car hard right before it. Not changing gears early.

Murt2024

Was the engine heated up fully before bringing it to the test center? Like a 30KM drive before it.

daarmcd

Why do you need an NCT

bobbyss

https://www.boards.ie/discussion/comment/121612272#Comment_121612272

Thanks a lot. Do you think a 100 miles on the motorway in 4th to 80kph on the day of the retest is ok?

User1998

https://www.boards.ie/discussion/comment/121612328#Comment_121612328

I would think that 100 miles is a bit excessive. Just add the dipetane in a week before the re test, drive the car hard, and right before the test drive it hard again and arrive with a hot engine. That should do the trick.

antodeco

Make sure you engine is hot before bringing it in. Annitlian tune up once the engine is hot. Do a couple of nice high revs (I'd recommend red line it, but I know what people would say!)

BK5

Thought cars didn't get NCT'd till 4 years old?

bobbyss

https://www.boards.ie/discussion/comment/121612414#Comment_121612414

Thanks.

Annitilian tune up?

High revs- red line it?

This is like a foreign language to me. Could you explain in the simplest terms please?

User1998

https://www.boards.ie/discussion/comment/121616173#Comment_121616173

Italian tune up = red line it

?Cee?view

“NCT frequency and test due dates

Private cars must undergo a roadworthiness test when they are four years old and every two years thereafter until their 10th anniversary. After that they need to be tested annually.”

Why are you getting an NCT?

galvo_clare

Brought the car for an Italian tune up a few years back. Evening appointment so was dark. Came off the motorway with roundabout and long slip road after that.

Something was niggling me about the car behind, so coming off the roundabout I gave it a final strong squirt but didn’t let it go beyond 100km/h.

The plainclothes i40 duly passed me, flicked on the blues for a second and drove on.

I’d love to know what they’d have said if they stopped me.

Field east

https://www.boards.ie/discussion/comment/121612303#Comment_121612303

Poster said that the emissions were outside the limit - hence all the discussion around the Diptane. The following points might be of interest to Bob:-

1) IMO you failed the test -re emissions- because you drive the car very slowly and you probably do short journeys most of the time - maximum 5km to and 5km back. The engine is nearly warm when you stop the car. That kind of driving is the ideal environment for the build up of carbon deposits in the engine firing/exhaust system and that leads to the failed test.

2) the Diptane along with a very hot engine while driving helps to dislodge the carbon buildup. I wonder - if you had the time if going through two bottles of Diptane might be even more effective.

3) Afull tank of fuel with Diptane will do ,say, 300 miles. IMO you do not have to do the 300 miles at high revs so as to get the engine very hot . You could spurts of, Say, 5 miles now and again And somewhat slower in between. If you are worried about the car overheating then just watch the temperature gauge

4)there are two types of diptane - one for diesel engines and one for petrol engines . Make sure you have the right one

5) as an above poster said ‘ read the instructions on the bottle’. From memory it’s a full bottle of Diptane to a full tank of fuel. Next time when filling up , ideally, put the Diptane in first and then the fuel.

6) as already said , arrive at the centre just before the appointed time having driven the car for the last ,say, 5km at high revs.

I am open to correction but that is based on my experience. Hope that has not confused you Bob

antodeco

^^^ the question asked why do they need an NCT is because the car is only 3 years old, and doesn't need an NCT until 4...

josip

Maybe the OP bought the car 3 years ago but it wasn't new at the time.

listermint

Either way once you pass it. Look to sell it on. You shouldn't have a diesel it's lying in the bushes awaiting further problems for you due to your range requirements and driving style. Sell it this year and get a petrol instead. Smarter choice for you.

Oscar_Madison

I failed test years ago because of a clogged exhaust and a low engine temperature- ever since I’ve arrived at the NCT centre with a red hot engine 😀- it really does make a difference- even a few months ago on a freezing cold day, I remembered that I hadn’t run the engine much over the previous months (second car hardly use it) so went for a good drive and made sure the temperature was way up - saw some deposits come out of the exhaust as it got to temperature so we’ll worth doing that before your NCT- haven’t failed an emissions test since

User1998

https://www.boards.ie/discussion/comment/121617812#Comment_121617812

They haven’t said whether its petrol or diesel. There is no emissions test for diesel cars only a smoke test so its most likely a petrol unless they are using the wrong terminology

listermint

https://www.boards.ie/discussion/comment/121617874#Comment_121617874

Warning flags for me where Qashqai and mechanic saying they aren't driving it enough..I'd put money down its a diesel.

magicbastarder

https://www.boards.ie/discussion/comment/121617874#Comment_121617874

there is an emissions test for diesel - the 'smoke' test you mention is an emissions test, it's an emissions test for particulates. in fact, i think you're the one using the wrong terminology!

https://www.ncts.ie/media/z55p1lpj/vir.pdf

Furze99

https://www.boards.ie/discussion/2058331157/advice-needed-please-failed-nct

What year is the car? What's the reg year?

3 Owls in a Coat

https://www.boards.ie/discussion/comment/121617489#Comment_121617489

I would hazard a guess that the car is possibly 3 years and 9 or 10 months old and in early for its test. I don’t know if there is the option of voluntary early testing on a car that doesn’t have its first test done.

Chippy01

''4)there are two types of diptane - one for diesel engines and one for petrol engines . Make sure you have the right one''

Wrong.

There is only one 'type' of Dipethane, and can be used with petrol, diesel, and home heating oil.

endacl

JLM Extreme Clean made a substantial difference. 2022 smoke reading was 0.390/m. Down to 0.050/m last year. I’m due an NCT in march, and she’ll be getting another treatment before that.

bobbyss

Thank you all. Its a 2000 car. Yeah as field east noted above I have low milage and sometimes not used for a couple of days a week. As I mentioned above a fellow at the exhaust centre suggested putting in a quarter of the bottle and a full tank of petrol and get on the motorway at motorway speeds. He also said to get the dipetane through the system before the test as traces could interfere with the reading.

From the helpful suggestions here I intend to use the whole bottle before the test and on the day of the test itself, with all the dipetane gone as per what the exhaust fella said, go for a spin and get the engine warmed up for test.

This would be a motorway run? How far? In 4th gear going at 80? Or any lengths at 100?

Many thanks to everyone for all the feedback.

User1998

https://www.boards.ie/discussion/comment/121630998#Comment_121630998

Any type of driving for 15 minutes or so will heat up your engine. Just make sure to hold the lower gears a bit longer and let the engine rev high.

Depending on the test centre you might have the option of waiting in your car, do this with the engine still running.

EarWig

I failed on emissions one year. My mechanic couldn't find any issue. It was low mileage.

Drove 20km on the motorway in fourth gear at 100kph before the retest, so the revs were high.

Emissions score were perfect second time round.

Luna84

I done a drive with dipetane for emissions once. I drove up and down the motorway as fast as the car would go. You don't have to go to the same extreme as me I was young it was like 16 years ago.

bobbyss

https://www.boards.ie/discussion/comment/121631430#Comment_121631430

Thanks.

Does it matter how long you finish that particular drive and then go to the NCT? Or did you go directly from the drive to the test? What was your wait time? I suppose what I am asking is how long does the engine stay hot for?

I know so little about this stuff I didn't even know it was important to have the engine hot.

Luna84

https://www.boards.ie/discussion/comment/121656053#Comment_121656053

Drive it hard on the way to the test centre and what I done is drive up and down the road usually at an industrial centre with the NCT is for a few high rev blips so it should still be hot when the tester takes your car.

EarWig

https://www.boards.ie/discussion/comment/121656053#Comment_121656053

I went direct to the NCT after the drive.