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05-01-2019, 18:36   #1
Under His Eye
 
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NCT smoke fail

The auld lads diesel jeep was in for the test and failed the smoke test. Reading was 6 instead of the allowed 3.


Is there anyway to get this down easily?
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05-01-2019, 18:43   #2
Rows Grower
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The auld lads diesel jeep was in for the test and failed the smoke test. Reading was 6 instead of the allowed 3.


Is there anyway to get this down easily?
You can get a product made by Wurth, I think it's called Dieselcure.

Add it to the fuel tank a couple of hundred km's before the retest and again about 50km before the retest and it should help.

I'm sure someone else will have more knowledge of exact way to use it for best results.
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05-01-2019, 18:46   #3
derra_121
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The auld lads diesel jeep was in for the test and failed the smoke test. Reading was 6 instead of the allowed 3.


Is there anyway to get this down easily?

Rev the absolute ****e out of it and drive for approx 30 min constant (motorway or so) to get the engine up to temperature directly before you drive to the centre.

Hotter your diesel engine the better the chance of passing.
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05-01-2019, 18:55   #4
Littlehorny
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Put a fiver's worth of petrol with twenty quids worth of diesel into an old Peugeot that had failed before, drove the stones out of it and it passed on the re-exam.
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05-01-2019, 19:16   #5
Del2005
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Get the thing fixed properly and stop pumping noxious fumes into the atmosphere.
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05-01-2019, 19:30   #6
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Get the thing fixed properly and stop pumping noxious fumes into the atmosphere.
You must have very little to worry about that you take the time to chastise someone looking for advice.
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05-01-2019, 22:34   #7
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Basically much the same advice as already given. Try dipetane, a fivers worth of petrol with around €50 of diesel ( not much less). Drive it along a decent road for about 4/5 miles at around 60/70 mph in 3rd gear just prior to the test.
Above everything else do not let it idle outside the NCT Centre for more than a 30 seconds or so when you get there.
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06-01-2019, 11:58   #8
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Get the thing fixed properly and stop pumping noxious fumes into the atmosphere.
Everyone loves a cheap or free solution before paying a fortune.

I say rev the shoite out of it until kingdom come, then put it through again when the engine is hotter then the fires of hell in damnation!
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06-01-2019, 12:04   #9
Del2005
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You must have very little to worry about that you take the time to chastise someone looking for advice.
I worry about people sticking plasters over major issues. If a car is putting out too much smoke then it's faulty and needs to be fixed. But people will try everything possible then to fix it.

There's a reason why we have limits on the noxious emissions.
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06-01-2019, 12:11   #10
George Dalton
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In the vast majority of cases where an older (pre-DPF) diesel fails on emissions there is actually nothing wrong with the car. A lot of people’s driving style means the engine never reaches high revs or sustained peak load under normal driving. This means there is a certain amount of soot sitting in the exhaust. Then the vehicle goes for NCT/CVRT and the engine is revved to the limiter and all the crap comes out of the exhaust and causes a fail. A good Italian tuneup is all that is required to ensure a pass.
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06-01-2019, 14:53   #11
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....and many well-meaning NCT Receptionists will often tell Diesel Owners to let the Engine run while waiting to be tested "to make sure it's warm".
Probably the worst thing you can do just before the Smoke Test.
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06-01-2019, 14:56   #12
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....and many well-meaning NCT Receptionists will often tell Diesel Owners to let the Engine run while waiting to be tested "to make sure it's warm".
Probably the worst thing you can do just before the Smoke Test.
I have never gotten that in over 10 years continuously driving diesels. In fact they tell you not to leave the keys in the car while waiting to be tested.
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06-01-2019, 18:54   #13
mgbgt1978
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I have..... twice.
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06-01-2019, 19:26   #14
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I have never gotten that in over 10 years continuously driving diesels. In fact they tell you not to leave the keys in the car while waiting to be tested.
Now that you mention it, I often had to go back out and get the keys for the receptionist.
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06-01-2019, 21:03   #15
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OP,
To get the smoke opacity down, a good run prior to the test should help.

You havnt stated what make and model of jeep it is.
I'm assuming it's an older vehicle?

If a good run doesn't sort it, I'd be speaking with a diesel mechanic before using any additives.

It's could be down to a faulty fuel pump or bad injectors.
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