Smoke test FAIL

Just failed mot on smoke test and a couple of other bits nowt expensive thank god.Whats the best way to get through it.Engine oil and air filter only about 6 months old and the engine was warm.The mot guy says use some Diesel Magic.Any thoughts. Cheers
On a further note what causes the elevated smoke levels

What colour is the smoking? Have you tweaked your fuel pump this often causes a little more smoke. I also thought that you couldn't be failed on smoke, I never never heard anyone fail on it before. Maybe go to another mechanic lol

Black smoke.No nothing been tweaked well not since i have owned it.As for not failing, i saw the results on the probe and it said Fail so dont know about that.

The injectors could be on the way out, maybe if your struggling I have heard turning the turbo up could counteract the problem. Check your fuel pump, if your standing at drivers wheel looking at it on the left side underneath the pipes you will see a screw with a 13mm nut if there is still a black plastic cap on it hasnt been tweaked. What is the tick over rpm?

JimMatthews said:

What colour is the smoking? Have you tweaked your fuel pump this often causes a little more smoke. I also thought that you couldn't be failed on smoke, I never never heard anyone fail on it before. Maybe go to another mechanic lol

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Smoke is the only test that the older diesels have, if you look in the on line MOT testers manual you will see :

Reason for Rejection.

1.The exhaust emits dense blue or clearly visible black smoke for a period of 5 seconds at idle.
2.The exhaust emits dense blue or clearly visible black smoke during acceleration which would obscure the view of other road users.

I will need someone dodgy then because it's like stars in your eyes behing my disco after I turned pump up lol. Just have to distract the tester haha

running on veg reduces the smoke test level, may be worth a try.

JimMatthews said:

The injectors could be on the way out, maybe if your struggling I have heard turning the turbo up could counteract the problem. Check your fuel pump, if your standing at drivers wheel looking at it on the left side underneath the pipes you will see a screw with a 13mm nut if there is still a black plastic cap on it hasnt been tweaked. What is the tick over rpm?

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The tick over is about 800-900 .
What is causing the smoke is it too much fuel for the air input ie uncombusted fuel.

The tickover is a little high but not massively mine ticks at 1100 rpm because pump turned right up. Yes it's just too much fuels to air so just check simple things like air filter and snorkle if you have one 1st failing that you can either compensate by turning up the boost or check the injectors. I have never run on veg oil. Always heard it smokes more but I'm not sure. But would deffinatly do simple checks before going major.

chuck bit of 2 stroke in there

Try cleaning out the intercooler and give the turbo bearings a little wiggle. Black smoke is often over fuelling or lack of air.

I have been told that changing fuel filter and filling it with injector cleaner often works. Just let it idle for ten mins then a good run with no need to hammer it.

noiseboymart said:

Just failed mot on smoke test and a couple of other bits nowt expensive thank god.Whats the best way to get through it.Engine oil and air filter only about 6 months old and the engine was warm.The mot guy says use some Diesel Magic.Any thoughts. Cheers
On a further note what causes the elevated smoke levels

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If it were me I would be giving her and engine oil and filter change, plus changing the air filter. Before arriving at the mot place make sure she has a good fast run to clean out any shît in the engine.

+1 on the veg oil. always works on mine. how dense is the black smoke. mine has its pump tweaked, and dose smoke abit under load, infact it smoke a fair bit, but it went through on the smoke test. Cleaning out the intercooler will help a huge amount, gets rid of the oil and gunk trapped in there. Also as above check the turbo, as if the seals are shot, not will give you extra smoke, or worse if they let go all togther, there is a big chance of a run away engine

Oil and filter and keep it in second gear whilst driving and reached maximum rpm hold your foot flat to the floor for 2/3 seconds watch the ****e all Come out. Then go And get your Retest. Used to fail alot of diesels for the same
Thing. And it's down to being driven around like miss daisy.

Funkykipper said:

Try cleaning out the intercooler and give the turbo bearings a little wiggle. Black smoke is often over fuelling or lack of air.

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+1

Easy job and really stopped mine from smoking.

RKServicing said:

Oil and filter and keep it in second gear whilst driving and reached maximum rpm hold your foot flat to the floor for 2/3 seconds watch the ****e all Come out. Then go And get your Retest. Used to fail alot of diesels for the same
Thing. And it's down to being driven around like miss daisy.

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+1 again. I was told this was called the Wide Open Throttle test or something.

I regularly give it a blast through.

Nice straight bit of motorway and floor it. All the cr*p really does come out.

get rid of the EGR valve if its still fitted! run it on a bit of veg oil and take it for a good thrashing down the motorway you will soon have it cleared out.

Thanks for all the input here.Changed oil and filter along with air filter and passed no probs.Opacity went from 3.95 down to 1.6.

noiseboymart said:

Thanks for all the input here.Changed oil and filter along with air filter and passed no probs.Opacity went from 3.95 down to 1.6.

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That's very good news - well done!

Dave