# Giving my car a good run before the NCT



## Brendan Burgess (4 Apr 2016)

I had my car serviced last week and I have the NCT tomorrow.  I only drive about 5000 km a year, so the mechanic suggested taking my car for a good long spin beforehand as that improves the emissions.  

I hadn't heard that before and on this website, I see 

"Give the car a good run beforehand as well so the engine is up to operating temperature. Arrive in plenty of time for your test." 

If I am in traffic on the way to the test centre, could it result in a poor reading?  Should I take the car for a 20 km spin on the motorway? 

Brendan


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## odyssey06 (4 Apr 2016)

I was given similar advice with old car to make sure you get car to operating level if concerned about emissions. So a spin could help. I was fortunate that my local centre is against the traffic. The car passed ok so it doesn't hurt.

Good luck with the car. Don't forget to buckle up the rear seat belts. Have heard that's a bugbear of the staff.


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## horusd (4 Apr 2016)

I nearly always take it for a spin on the M50 before a test.  The high temps. apparently burn-off the gloop in the pipes.  Or, at least that's what my mechanic tells me.


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## odyssey06 (4 Apr 2016)

Plus don't get to your appointment way too early or the engine will have cooled down again by the time it's seen.


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## Brendan Burgess (5 Apr 2016)

horusd said:


> I nearly always take it for a spin on the M50 before a test.



What does a "spin" mean?  10k  or 50k? 

Brendan


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## odyssey06 (5 Apr 2016)

I think you want to have the car driving i.e. not stuck in traffic for at least 20 minutes if you can...


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## Boyd (5 Apr 2016)

I think you're overthinking this! Just drive to the NCT as normal and arrive on time. If it passes it passes, if not get it sorted. Loads of old wives tales about NCT inspectiors not liking this and that etc. The last time I was at NCT I filled up the windscreen wiper reservoir using a 7up bottle I filled in the NCT centre. This was in full view of the mechanic who was about to start testing the car......still passed.


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## odyssey06 (5 Apr 2016)

Emissions are a special case... you really don't want an older car being tested with a cold engine. The same engine cold v hot will have a totally different emissions reading. The same engine could pass hot and fail cold, and sorting out emissions problems is not trivial.


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## Palerider (5 Apr 2016)

It makes a difference, drive in a lower gear than normal keeping the revs up, a couple of miles will be fine once the engine gets time to heat up, the purpose is to blow out deposit build up primarily carbon that through normal careful low revving journeys can build in your exhaust and throw off your emissions at the centre.

I drive in 3rd at 3500 - 4000 rpm for about four miles before I get to the centre and once the car is up to operating temp.


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## Dan Murray (5 Apr 2016)

Dear Brendan

If your car's emissions are excessive, surely the right thing is to rectify the emission levels rather than trying to circumvent the test? It's such an attitude which saddens me and makes me fearful that timely progress will ever be made in the fight against global warming!


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## horusd (5 Apr 2016)

Brendan Burgess said:


> What does a "spin" mean?  10k  or 50k?
> 
> Brendan


HI Brendan, I do my test over near the airport and I live on the Northside, so I usually take it for about a 20 - 30 km run up to Blanch/town and around. No more than around 20 mins.  The mechanic said that you need to get up to 100 or 120 (for about 15-20 min) to clear the gunk.  There are loads of options off the M50: M1 or N3 (Derry road) where you can hit that speed and turn back easily.  If the M50/M1 busy the N3 is nearly always pretty empty and you can drive at speed safely.


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## odyssey06 (5 Apr 2016)

Dan Murray said:


> Dear Brendan
> If your car's emissions are excessive, surely the right thing is to rectify the emission levels rather than trying to circumvent the test? It's such an attitude which saddens me and makes me fearful that timely progress will ever be made in the fight against global warming!



If they are not excessive when driving, there is no real problem to rectify? Once the engine has gotten up to its operating temperature the emissions could be ok.
If the car is failing at operating temperature then there is a real problem.
Fingers crossed in this particular instance there is not.

The car should be tested at road condition temperatures. 
Remember the scandal with Volkswagen and its defeat devices? Because the 'smart' car knew it wasn't in a road condition. With old cars they are too 'honest'.


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## Leo (5 Apr 2016)

Dan Murray said:


> Dear Brendan
> 
> If your car's emissions are excessive, surely the right thing is to rectify the emission levels rather than trying to circumvent the test? It's such an attitude which saddens me and makes me fearful that timely progress will ever be made in the fight against global warming!



No where was it stated that his emissions were a problem. It's such jumping to conclusions and subsequent accusations saddens me!


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## Sue Ellen (5 Apr 2016)

Not being nosey or anything but did it pass?


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## roker (5 Apr 2016)

Don't have to worry about taking mine for a spin. the test centre is an hours drive away. If it fails that another hours drive plus return trips


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## mathepac (5 Apr 2016)

The real answer, as usual, is that it all depends. Petrol or diesel? Old engine or new? Do you use an additive with your fuel e.g. dipethene? Does you car have a cat fitted and must it have one? 

General rule of thumb is to have the car tested when the engine is warm. Bring your second key and arrive with your engine warmed up. Check in and pay, hand in your keys and then sit in your car with the engine ticking over until the tester comes to take it. "I was charging the phone, no mains charger with me bud."

I anyone has specific questions about their car, maybe they can be addressed with specific answers.


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## Brendan Burgess (5 Apr 2016)

Sue Ellen said:


> Not being nosey or anything but did it pass?



Last time I arrived about an hour early and they did it pretty much immediately. I was about 30 minutes early this time, and I had to wait the full 30 minutes.  But my emissions were well below the minimum level. 

Unfortunately, for some bizarre reason my rear fog light is white rather than red, so he failed me for that.  But he told me very helpfully that I can get a special tape from a motor factor which will turn the light red.   

Good job, because I rang Audi about it and they would have to order the part which is €120 and they would charge more for fitting it. 

Brendan


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## odyssey06 (5 Apr 2016)

You're almost over the line so.


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## newirishman (6 Apr 2016)

mathepac said:


> The real answer, as usual, is that it all depends. Petrol or diesel? Old engine or new? Do you use an additive with your fuel e.g. dipethene? Does you car have a cat fitted and must it have one?
> 
> General rule of thumb is to have the car tested when the engine is warm. Bring your second key and arrive with your engine warmed up. Check in and pay, hand in your keys and then sit in your car with the engine ticking over until the tester comes to take it. "I was charging the phone, no mains charger with me bud."
> 
> I anyone has specific questions about their car, maybe they can be addressed with specific answers.



There's not many things that drive me more mad than people sitting in a parked car (or e.g. waiting in front of a closed railway crossing) with the engine running for no ... reason.
Apart from fuel waste it is a clear sign that the environmental impact of burning fossil fuels just doesn't seem to be registering as a problem. 
Apparently petrol is still too cheap.


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## T McGibney (6 Apr 2016)

newirishman said:


> Apart from fuel waste it is a clear sign that the environmental impact of burning fossil fuels just doesn't seem to be registering as a problem.



Not sure if it is problem in the first instance. It certainly isn't an issue in terms of a motorist trying their best to get their car to pass an NCT test, which is what we're discussing here.


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## newirishman (6 Apr 2016)

T McGibney said:


> Not sure if it is problem in the first instance. It certainly isn't an issue in terms of a motorist trying their best to get their car to pass an NCT test, which is what we're discussing here.



There's recommendations in this thread to have a "drive around" to clean the engine (from what is not entirely clear), or to leave the engine running so it is warm when the car is picked up for the test.

I am not aware that there it is a requirement when presenting your car for the NCT to have the engine warmed up, or having done a drive around beforehand. I am sure one can manage to pass an NCT even when presenting the car with a cold engine and without giving it a good run.
Car service maybe, ensure that the engine is properly setup?

It is also possible to modify the on-board computer specifically to pass the NCT. I think we can all agree that this is also a bad idea?


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## T McGibney (6 Apr 2016)

newirishman said:


> There's recommendations in this thread to have a "drive around" to clean the engine (from what is not entirely clear), or to leave the engine running so it is warm when the car is picked up for the test.
> 
> I am not aware that there it is a requirement when presenting your car for the NCT to have the engine warmed up, or having done a drive around beforehand. I am sure one can manage to pass an NCT even when presenting the car with a cold engine and without giving it a good run.
> Car service maybe, ensure that the engine is properly setup?
> ...


Read the previous posts FFS.


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## Leo (6 Apr 2016)

newirishman said:


> There's recommendations in this thread to have a "drive around" to clean the engine (from what is not entirely clear)



A little reading on the workings of the modern internal combustion engine will clear that up for you. 



newirishman said:


> I am not aware that there it is a requirement when presenting your car for the NCT to have the engine warmed up, or having done a drive around beforehand.



The NCT test methods introduce some strain on the engine to simulate performance under load, doing such tests on a cold engine can result in damage, hence the waiver you are required to sign on presenting your car for test.


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## Leo (6 Apr 2016)

newirishman said:


> There's not many things that drive me more mad than people sitting in a parked car (or e.g. waiting in front of a closed railway crossing) with the engine running for no ... reason.
> Apart from fuel waste it is a clear sign that the environmental impact of burning fossil fuels just doesn't seem to be registering as a problem.
> Apparently petrol is still too cheap.



Frequently stopping/starting an engine not specifically designed to withstand it is not recommended. Engines with start-stop built-in use more robust starter motors, more deep cycle capable batteries and alternators to handle the increased charging required, along with lower friction crankshafts and bearings to reduce the energy requirement to re-start the engine.


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## newirishman (6 Apr 2016)

Leo said:


> Frequently stopping/starting an engine not specifically designed to withstand it is not recommended. Engines with start-stop built-in use more robust starter motors, more deep cycle capable batteries and alternators to handle the increased charging required, along with lower friction crankshafts and bearings to reduce the energy requirement to re-start the engine.



(I know we are probably a bit off topic now):

That's is not correct, and probably hasn't been for many years (so also for older cars).

Here's a good starting point
http://sustainability.stackexchange...-engine-off-while-standing-at-a-traffic-light
and this one as well
http://physics.stackexchange.com/questions/57794/calculating-engine-starter-s-energy-use

Funnily enough, idling the car for more than 30 seconds is illegal in many countries in Europe (duration depends on country)


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## Leo (6 Apr 2016)

I wasn't arguing about fuel savings, just the premature wear of starting components and shorter battery life. I'd prefer not to have my starter motor fail every 3-4 years as the first article proposes, even if it did save me a little overall.


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## mathepac (6 Apr 2016)

newirishman said:


> There's not many things that drive me more mad than people sitting in a parked car (or e.g. waiting in front of a closed railway crossing) with the engine running for no ... reason.
> Apart from fuel waste it is a clear sign that the environmental impact of burning fossil fuels just doesn't seem to be registering as a problem.
> Apparently petrol is still too cheap.


It's a trade off. Starting a stone cold engine and leaving it running for the duration of the test including the "revving" part of it will use more fuel than one that is at optimum operating temperature. It's an imperfect world and I have no perfect answers. At least there's a purpose to sitting outside the test centre with the engine running as against sitting at railway crossing.


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## mathepac (6 Apr 2016)

newirishman said:


> (I know we are probably a bit off topic now)


Do ya think?


newirishman said:


> Funnily enough, idling the car for more than 30 seconds is illegal in many countries in Europe (duration depends on country)


Spuds are cheaper in Tescos than in Dunnes but that won't get ya through the NCT


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## huskerdu (6 Apr 2016)

newirishman said:


> There's not many things that drive me more mad than people sitting in a parked car (or e.g. waiting in front of a closed railway crossing) with the engine running for no ... reason.
> Apart from fuel waste it is a clear sign that the environmental impact of burning fossil fuels just doesn't seem to be registering as a problem.
> Apparently petrol is still too cheap.



BUT - A warm engine idling uses very little petrol and starting an engine takes more petrol than when the engine is idling.

Your statement is only true if the petrol saved while the engine is idling, is less than the extra petrol needed to restart the engine.

If you are stopping your engine every time you are idling, you are using more petrol in some cases.
Do you know how long you need to be idling before it is worth doing ?


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## Brendan Burgess (7 Apr 2016)

huskerdu said:


> If you are stopping your engine every time you are idling, you are using more petrol in some cases.
> Do you know how long you need to be idling before it is worth doing ?



I did not know that. I turn off my engine at the Level Crossing as the gates can be down for a long time and I prefer the silence. 

Brendan


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## newirishman (7 Apr 2016)

Brendan Burgess said:


> I did not know that. I turn off my engine at the Level Crossing as the gates can be down for a long time and I prefer the silence.
> 
> Brendan



The general consensus seems to be that the cut-off point is round 7-10 seconds.


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## Leo (7 Apr 2016)

newirishman said:


> Funnily enough, idling the car for more than 30 seconds is illegal in many countries in Europe (duration depends on country)



Yet keeping a medium sized dog has the same ongoing impact on the environment as two large SUVs. Eliminating idling is a nice easy political win to pretend people are taking the environment seriously, but it's a trivial issue in the bigger picture.


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## newirishman (7 Apr 2016)

Leo said:


> Yet keeping a medium sized dog has the same ongoing impact on the environment as two large SUVs. Eliminating idling is a nice easy political win to pretend people are taking the environment seriously, but it's a trivial issue in the bigger picture.



Well, most people can't fix the bigger picture. But they can do small things that, if you think about it, don't have any negative impact on an individual. So essentially what you are saying there is just a bit of an excuse. 

I don't care about politics, but I do care about the environment, and what science might tell us.

Here's a very succinct summary, I recommend to spend 2 minutes to read it. Comes with a warning though, as it might cause a change of mind.

https://www.edf.org/climate/reports/idling


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## Leo (7 Apr 2016)

newirishman said:


> Well, most people can't fix the bigger picture. But they can do small things that, if you think about it, don't have any negative impact on an individual. So essentially what you are saying there is just a bit of an excuse.



No, I'm saying we need to focus more on the real causes of environmental damage and stop pretending we're taking action by addressing trivial issues.


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## mathepac (7 Apr 2016)

newirishman said:


> I don't care about politics, but I do care about the environment, and what science might tell us.
> 
> Here's a very succinct summary, I recommend to spend 2 minutes to read it. Comes with a warning though, as it might cause a change of mind.
> 
> https://www.edf.org/climate/reports/idling


Why read an Ahmuhrcan document where engine sizes are bigger and "gas mileage" and gallon sizes are smaller resulting in costs that in no way reflect the cost of European idling? What about some close to home science? And their cars don't take an NCT.


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## Brendan Burgess (7 Apr 2016)

mathepac said:


> And their cars don't take an NCT.



And they don't insist on rear fog lights either!  

Brendan


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