Hi all. I bought a 1999 Octavia and in my opinion in knocks spots of the Citroen C4. The problem I have is that sometimes when accelerating in thrid gear on motorways, the rev counter will reach 3500 and then there is a loss of power throughout the gears (as if the turbo was not there even though it can be heard). To solve this I have to switch the engine off and then back on again. My first thought was that maybe the injectors are clogged and need flushing with Redex or something similar but a friend of mine thinks it might be a power surge in the ECU.

My second problem is that I have had to remove the V-Polly tensioning damper as the bracket had snapped. A mechanic has told me that the unit should be there but there is no reason why the aux belt will suffer without the tension unit being there.

Any suggestions to the above problems would be appreciated.

Regards

with the limp mode issue it is probably the sticky turbo problem where the vnt mechanism in the turbo gets stuck causing an overboost and limp mode. Try a search, there are loads of threads about it.

:+1: for trundlenut's comments about VNT. See if you can get the car scanned for faults, most likely it will show an overboost fault. Other possibilities are MAF (generally drives like there is no turbo at any revs) or n75 failing. Might be worth checking your airfilter is clean(ish) - as that is a free check :-)

I would have thought that without the aux tensioner the belt would fall off?!

:+1: for trundlenut's comments about VNT. See if you can get the car scanned for faults, most likely it will show an overboost fault. Other possibilities are MAF (generally drives like there is no turbo at any revs) or n75 failing. Might be worth checking your airfilter is clean(ish) - as that is a free check :-)

I would have thought that without the aux tensioner the belt would fall off?!

Hi thanks for the responses. What is VNT and MAF? and what is an overboost fault please? I dont need a new turbo do I?

The belt was checked by a mechanic and he said that it wont jump off or snap due to the fact that the belt has adequate tension and so far (touch wood) it has done nothing.

The VNT mechanism is part of the turbo and comprises moveable vanes which change position dependingonengine revs and basically mean you get more power from the turbo. The MAF is a sensor which measures how much air is gong into the engine, if this gives dodgy readings the computer gets confused and the car won't run right.

The overboost fault is caused by the vanes in the turbo jamming in one position and then the the turbo makes too much boost when you give it some welly and the computer cuts the amount of fuel to stop the engine getting damaged, this is limp mode that you discovered makes you think your driving a tractor.

The cure for the turbo problem is to have it removed, stripped down and the muck which is jamming the vanes is cleaned off. You should not need a new turbo.

Ok thanks for the help. Its going back to the garage tomorrow.

As above with the turbo. For the snapped damper, probably caused by extra vibration transmitted due to a seized alternator pulley, it has a mechanism within it that allows it to freewheel in one direction.