I have a bora 150 TDI 53 plate 73k full history serviced only a few thousand miles ago.

I have in the last month changed the maf & coolant sensor was done 2 weeks ago.

The problem i am having is that the car throws alot more black smoke out the back when i take it past 2000 revs in any gear also it has on a couple of occasions missed for a split second like a quick glitch , as stated above in the service the oil , fuel and air filter was changed and all i have done since then is the new coolant sensor and the fan fix which now works perfect i must say thanks Op .

Me and one of the guys on here mike-R tested it a few weeks ago for MAF & Boost leak but all looked ok in Vag-com but now more than ever i get black smoke out the back which is a little embarrassing and i would like to know what would be the cause.

I must mention i have tried to tie the vac pipe going to the EGR to disable it but still the same any further ideas more than welcome.

It show No faults in Vag-Com as of yesterday .........would a faulty coolant sensor cause this ? as above thats all i have done different really in the past few weeks and i also feel my MPG is low ( Don't everyone ) but sometimes very low 30's and i have even seen it in the high 20's.

I don't want to sound rude here and please don't take offence but i am not interested in what your car does to mpg we have enough MPG threads now so i would ask people to make positive comments related to my thread.

Yes i think my car should see into the 40's on careful mainly town driving and carefull motorway driving 60 plus.

Sorry to rant on here but this is worrying me now and this is why i have started this thread in the hope someone can help me or had the same problem and cured it or maybe something i can test myself in Vag-Com.

Regards Andrew

 Did you make sure you got hte correct coolant temp sensor? theres around 3diff ones as they kept changin them and depending what one was in you have to get a new different one.

think theres like 2 pin black 2 pin green 3 pin black etc.

I got mine from German and wedish ended up getting a second one which fixed it.

Think GSF know about this so will advise.

 Well its overfuelling. So either you have a blockage in the Air intake/ filter... there is a break somewhere Air intake side - intercooler pipes etc. Or the new maf is ******. try running the MAF run again and log values to see what air you are getting.

 Headworks i got the correct Coolant 4 pin green one.

Steevee i will look into what you have said and it makes sense and regards to the MAF being goosed again you could be right and i will have to do some logging again.

I hope it's nothing serious crossing my fingers legs and toes.

I will be doing the egr and inlet manifold clean also hopefully so i can take that out of the problem equation.

Was gonna say an egr clean wouldn't go amiss. Take the intercooler pipe off the egr and have a peek inside to see how crudded up it is then you know if it's potentially a cause or not. On my 110 (non-PD) the egr was quite crudded up but I didn't have any running problems or heavy smoking. But cleaning it did remove my slowdown judder (typical 110 fault) and did reduce exhaust smoke very slightly but not by a major amount.

I suspect your fault is more than just the egr.

For the MAF, try unplugging it and going for a short drive to see if its any better. With it disconnected the ECU should substitute its value for a preset value

sorry, just a question.

Garfie, what do u think? good idea to clean the EGR-SMIC pipe on a (PD) engine too?

cause I never cleaned that pipe, but the EGR (atm it is disabled)

Generally all you will find in the intercooler and pipework before the EGR is oil residue. This sometimes builds up enough to make it worth cleaning out but its not essential. The worst part on the intake is the EGR and the inlet manifold as its this section that gets the exhaust gas (and soot) through it. Disabling the EGR will stop the exhaust gas entering the inlet in the first place but is on really beneficial if the EGR valve and inlet manifold are cleaned out at the same time.

Check here to see how mine looked when I cleaned it out at about 100k:

http://uk-mkivs.net/forums/p/89262/628676.aspx#628676

 **UPDATE** When i have had a look under the bonnet this morning i was looking at the lower intercooler pipe and it looks like it has popped out showing most the metal flange what should be firmly seated into the other part of the intercooler section.

Let's hope this is my problem ?

 Yep thats probably all it is mate! that would cause the over fuelling.

 I did get that with my PD150, I replaced the metal turbo pipe on the drivers side and replaced a couple of the rubbery pipes both drivers and pass side, change clips etc, but still kept blowing off (so to speak). Think the 150's are too powerful for their own good.

Normally can hear when its happened as the boost 'tsssss' goes to a 'whoooooosh' (hope you like how technical I am with this).

 hi nochex

my bora is having the same problems as yours did the intercooler pipe solve

the problem

cheers

wynn

 Yes sorted

Was abit slow on this and sounds like its sorted Andy  ,  but i got a huge amount of MPG back when i cleaned the EGR and Intercooler out.. took both completely off and used brake cleaner on then both.. Also reduced smoking a fair bit.. intake very soon i think! its just abit more awkward to get at.

 cheers nochex

just take off the sump guard{couldn't see anything from the top}and the intercooler pipe was off a bit.took the pipe off completely cleaned it up and it looks like one of the lugs on the pipe that the circlip holds in position is damaged. need to get a new pipe!!!!!

The cost of a new pipe ( Genuine ) is about £100

ecosse:

 cheers nochex

just take off the sump guard{couldn't see anything from the top}and the intercooler pipe was off a bit.took the pipe off completely cleaned it up and it looks like one of the lugs on the pipe that the circlip holds in position is damaged. need to get a new pipe!!!!!

afaik thats a common problem, and theres a fix for it.