hi can I get some help. My octavia started to stutter when under load and accelerating and it got gradually worse especially under 1500rpm. I got the egr cleaned and it did improve for a while. Now it's back to stuttering and blowing black smoke. Recently EML came on which turned out to be the turbo which I got changed but performance was still same. Another mechanic then said intercooler was leaking so it was changed and egr valve was cleaned but again it's still stuttering and blowing black smoke Anybody out there have any other ideas what the problem could be. Could it be a fuel issue or air intake leaking.

not wishing to sound obvious but when was the fuel filter last changed   40k is crazy 

Hi. It's been serviced every 10000 miles. But I'll definitely check it. Thanks

Hi. It's been serviced every 10000 miles. But I'll definitely check it. Thanks

^{I would recommend looking at the rubber vacuum pipes from the turbo wastegate to the N75 valve for splits first.  However, if I was a betting man I would guess that the N75 valve is the culprit - the rubber diaphragm in the sensor is know to fail - when it does, the car generally runs rich, which in turn causes EGR / turbo etc to coke up, creating symptoms similar to what you describe.  I've not completed this on a Mk2 Octy, but generally on VAG cars this is a relatively simple DIY job - I have changed two in the past month on friend's cars with similar symptoms to yours.  The valve costs approx. £45 - £55, and you will probably need someone with VCDS to clear the fault codes for you - you can get cheaper non-OEM parts online, but the VAG ones in my opinion are fairly reliable and pretty good value.} 

 

^{Once you have changed the valve, treat the car to a couple of tanks of 'super diesel' (I assume you can get this in NI?) as this generally has more detergents versus ordinary diesel - this should assist with de-coking the car after it has been running in rich fuel condition.} 

Edited 6 August, 201510 yr by Black_Sheep

Cheers black_sheep. I'll definitely start checking that

any joy  :no:

Im not particularly knowledged as a mechanic or anything but I do think I had a recent incident which sounds along the same lines of what you may be experiencing... I also own a 1.9TDI engined Octavia.

 

I was travelling on the M62 back from Manchester to Leeds and having come out of the road works at 50mph had come upto speed at 70 when suddenly there was a shudder, I lost all power and with my foot to the floor in 4th could barely maintain 60. Having perhaps foolishly braved the journey home on fear of being stuck on the hard shoulder of one of the most dreaded motorways in the north I found the bottom of my engine bay drenched in oil and thought Id lost my car. 

 

Took it up to troys who said it was the turbo hose that had blown, they said they replaced the hose and the replacement blew as well. In the end it seemed that the turbo had gotten so clogged up with crap it was just tearing through hoses. What they did there after I believe was to use some turbo cleaner, most likely from FORTE which I know they use in their services to pour straight into the turbo (Ive heard people remove the air filter and tip it straight down?) and then blast the car round at really high revs, even encouraging me to fill up and jet the car round a bit to really clean things out. Since then Ive had no issue, and the cars been an absolute dream to drive, even giving a much better response from the throttle!  :p

 

I do enjoy pushing my car when I hit country roads but generally Im know to swiftly move through the gears, and unlike most be into 5th by 40mph and people have commented that perhaps this style of driving might not be so great for the car, so if you find you have a similar driving style to me, it could perhaps simply be that even with a well serviced car, if you dont get some cleaner through and push the car through its gears a bit more aggressively then things might get a bit clogged!

 

Hope this might have helped in some way and best of luck getting back up and running!! 

Well eventually it's been sorted by the 5th mechanic. The cam shaft had worn on one of the knuckles thus the loss of power. Hope this helps others with the same problem.