Diesel car fail NCT excessive smoke

jacknife

i failed the NCT first time round for excessive smoke and a few other minor issues, got the issues sorted.

The garage couldnt find anything on the diagnostics, he said there was an open circuit, the car drives fine, accelerates, no loss of power, etc

He put additive in it and a cloud of black smoke came out, i put additive in at the weekend and drove it hard today and was seen as soon as i went in

The car still failed on excessive smoke

I have noticed its hard on oil maybe 2 litres per month but i do a lot of driving

Anyone any ideas of what to do or how can i find the problem

Go to a different garage. Bit being able to diagnose & rectify a smokey diesel is appalling IMO

Burning 2l oil a month suggests it's w@nked.

Macdarack

jacknife wrote: »

i failed the NCT first time round for excessive smoke and a few other minor issues, got the issues sorted.

The garage couldnt find anything on the diagnostics, he said there was an open circuit, the car drives fine, accelerates, no loss of power, etc

He put additive in it and a cloud of black smoke came out, i put additive in at the weekend and drove it hard today and was seen as soon as i went in

The car still failed on excessive smoke

I have noticed its hard on oil maybe 2 litres per month but i do a lot of driving

Anyone any ideas of what to do or how can i find the problem

An "open circuit "is very vague, any more on that, what are you driving?

CramCycle

2 litres of oil a month, jaysus, something isn't right.

endacl

CramCycle wrote: »

2 litres of oil a month, jaysus, something isn't right.

Maybe the op is driving a chipper van?

2L a month ?
how many KMs are you doing a month ?

OP, you might as well not to fill up the fuel tank and just drive on motor oil with that sort of consumption.

If it was me and it had a turbo (as any half modern diesels have) I would look into that first especially if the smoke is white/blue instead of black.

KB22

Two litres a month? Is it two stroke!!!!!

BrokenArrows

OP, doesnt matter how much you are driving you should generally not need to topup the oil between services, never mind 2L per month. Did you tell the mechanic this?

Dexter2019

What does the NCT report state under the smoke test results?

jacknife

Thanks Guys,

I do about 4k KM per month, car drives perfect, no loss of acceleration or power

it was very hard start a while back and got diagnostics done and was told the air flow meter and the glo plug unit was gone and the battery, i changed the battery and no issues starting after that

was in the garage today and they gave me Smog Doctor VB35 they said that has instant effect

the NCT report said Exhaust Smoke and CO/HC Lambda (2/3) Smoke 5.840/m Engine Oil 82 Degree C Turbo 3.00/m

jacknife

jacknife wrote: »

Thanks Guys,

I do about 4k KM per month, car drives perfect, no loss of acceleration or power

....................

the NCT report said Exhaust Smoke and CO/HC Lambda (2/3) Smoke 5.840/m Engine Oil 82 Degree C Turbo 3.00/m

4000kms/month is 2500 miles.
With emissions that high it's almost guaranteed that the 2 litres/month oil use is being burnt and not leaked.
Your garage are jokers if they are relying on various bottles of treatments to attempt to remedy the issue.
You are potentially burning 8 litres of oil every 10,000 miles travelled.........

CPTM

Here is why the NCT is good I suppose! It definitely sounds like you need another garage to look at that for you.

zilog_jones

BrokenArrows wrote: »

OP, doesnt matter how much you are driving you should generally not need to topup the oil between services, never mind 2L per month. Did you tell the mechanic this?

Oil consumption of around 1 litre per 1,000 km is within acceptable limits for modern cars, and they say they're doing 4k km per month. I don't think the amount of oil consumption is necessarily the problem here.

But we still don't know what car it is, and they also claimed the MAF was "gone" at some stage but didn't say if it was fixed. A faulty MAF is surely going to cause incorrect fuelling.

zilog_jones

zilog_jones wrote: »

Oil consumption of around 1 litre per 1,000 km is within acceptable limits for modern cars..............

Folk will believe any drivel in an owner's manual these days.
Any modern car using 1l of oil every 1000kms has an issue......... it might be straight from the factory but there's something wrong.

zilog_jones

Well obviously it's not without issues, probably piston rings or something, but it's within acceptable operating tolerances even if it sounds like a lot. It's only when you go beyond that then you're likely to have emissions issues, damage the cat, etc.

wonski

If my car burned 10l of oil every 10k miles I wouldn't even bother with oil service. It would run on a fresh one all the time

jacknife

would it have anything to do with the air flow meter?

zilog_jones

A faulty MAF could cause it to run rich, which will create excessive smoke.

We still don't know what car you have

Alanstrainor

zilog_jones wrote: »

A faulty MAF could cause it to run rich, which will create excessive smoke.

We still don't know what car you have

jacknife

zilog_jones wrote: »

A faulty MAF could cause it to run rich, which will create excessive smoke.

We still don't know what car you have

07 Renault Scenic

jacknife

Got it sorted, it was the air flow meter, no more smoke or oil burning

Thanks guys for all your replies

beauf

Who sorted it.

How does a maf resolve 2l/month of oil consumption?

Dexter2019

Augeo wrote: »

How does a maf resolve 2l/month of oil consumption?

It doesn't!

jacknife

i dont know only that theres no more black smoke and the oil level doesnt drop