Smoke on start up. What the problem?

**DG01** · 15th February 2008, 22:44

Hi everyone.
Is has been a while since I've lasted posted a message but I use the site all the time as everyone knows so much info its great to solve problems and find out new things to do with the vectras.

Anyway can some help. My car has been in and out of the stealers with an old problem that a few members have had already but I am still trying to solve. Please see pasted text from old thread:-
need some help on this. ! 46K 150 bhp CDTI. this car has had a lot parts replaced to try and slove a fault by the dealers. The problem is after the car has been resting for over 2 hours it starts up ruff and above ave. smoke comes out the back. I can stop this by either v lightly touching the acc pedal or un-plugging either the MAF, boost sensors to go to basic settings. Both of these sensors are new. the idle and smoke disappear within 10 secs and all seems ok.

The car does not do this when on a cold morning start and does not smoke etc after leaving it for 8 hours just anything upto 6 hours!! It,s not the turbo or injectors as that has been done as well.

Does anyone know what the solution to this problem is as my car has the exact same symptons. I have already had the EGR replaced and the car is getting a new coolant sensor next week. Do you think this will help or is it something else?

Thanks for reading folks ! Happy days

**nutron** · 16th February 2008, 11:30

Is the car running fine otherwise? If so, I would leave it (unless the smoking it so bad it would fail an mot) as you could spend your whole life at the dealers.

**DG01** · 16th February 2008, 22:24

Yeah the car runs great as far as I can tell, the performance is good and the engine sounds fine. I get not bad miles to the gallon but I think it could be better. The worry I have is that when the warranty runs out (June 08) that is when the problem will become really bad and I have to sort it myself £££. The thought is at the momment if that it may be the coolant sensor being faulty and this is being changed next week. The thoery is that when the car is still warmish the sensor if missreading and the ECU is delivering to much fuel to the engine and therefore creating to much fume / smoke.
Also the reason I want this fixed is that when I start the car up and this smoke comes from the back it is really embrassing to have such a great car bad it it looks like it is broken becausse of the fume coming from the back.

I will see what happens when they fit the new coolant sensor, fingers crossed again.

Thanks for the reply, also not sure if this happens to other diesels as I have been a petrol car person before this CDTI?

**plasma** · 16th February 2008, 22:30

Mark GSi had this problem and VX tried oh soo many things to fix it.. They couldnt in the end

**Gsi3.2** · 17th February 2008, 10:20

yep..we sold it to get rid..

..As my old dad above said..it was a shed..

we had so many new parts on it, and so many software updates which did no good..in the end their advice was just to rev it hard from cold

to get it warm enough to stop it running rough..which is very bad practice...

Hence, after 18 months on dodgy diesel ownership it's gone and a 2.8T has taken it's place..we never ever found out what it was that was causing it..

**nutron** · 17th February 2008, 10:36

The coolant sensor should not effect fueling, the MAFS had a temp sensor which is what the ECU uses to calculate fueling along with the pressure sensor on the manifold.

You say it smokes when warm though rather than cold? Maybe the lamba sensors is ******ed?

**Gsi3.2** · 17th February 2008, 10:45

slight misread Nutron..he says it's on startup....the same fault as we had on our 150..

..it just magically clears after 10 -60 seconds or if you boot it hard for 30 seconds..

I don't know about DG01...but we had all the sensors changed on ours..all to no vain..

..

**DG01** · 17th February 2008, 17:24

Thanks for getting back to me guys. The car is really good and I don't want to get rid of it because of this. The rest of the car is great, it also runs and sounds fine when ever is started and the performance is always good. I am not losing oil from the engine so I reckon I am not burning oil, thats why I think it is diesel. Although when I bought the car the garage gave the car an oil change and I am not sure what oil they used, so I am planning to change the oil next weekend to a fully syntheic 3w 30 or 10w 40. This make have a good affect with solving the problem. The stealers have said the car is in good order and no faults are shown on the ECU. The smoke on lasts about 5 secs but the engine sounds and feels fine. Its just a pain in the ***.

I have read some other threads with the same problems KM101 and Keith101 and a few others but I can't remmeber there names.

Again I really like the car and the engine apart from this annoying niggle.

What does the MAF sensor do ?
What does the Lamba snesor do?
Are the haed and dear to fix?
Which oil do you use in your car?

Much appreciate your help guys.

**Gsi3.2** · 17th February 2008, 17:37

the MAF sensor measures the amount of incoming air into the engine

the lambda sensor tells the engine what the emissions are..a feedback device

the head is pricey, but very unlikely to be the problem honestly

we used 5W30 fully synthetic oil..VX's own ..changed every 6,000 miles.

**nutron** · 17th February 2008, 17:39

I use a 0W-40 as it is thin when cold but maintains viscosity when hot. The MAFS measures the amount of air flowing into the engine and the temperature of that air. This allows the engine to calculate how much fuel to put in. The Lamba sensor sits in the exhaust and tells the engine the fuel/air ratio of the exhaust so it can make further adjustment to the mix. The MAFS is a 10 minutes job but the Lamba sensor is a pain to get to, took me hours to get the pre-cat out so Vx will probably take days.