Your advice is desperately needed.

My 2002 Octavia vRS has developed a problem and my local dealer are unable to cure it.

At full throttle and in all gears at anything from 4000rpm and above, it goes rapidly on and off boost, feels almost like a misfire.

My dealer originally diagnosed this as a faulty lambda probe and reset it which cured the problem temporarily. After approx 500 miles it came back and was once again diagnosed as a faulty lambda probe. This was eventually replaced and once again the problem was solved. Unfortunately it's back again and I am at a loss.

Has anyone else here experienced the same thing? How did you cure it? Can anyone please offer some suggestions. I would be grateful for any help/suggestions/cures.

Thanks,

Andrew

Coil packs? Throttle body needs cleaning? air mass meter? Which probe was showing faulty? Was it faulty or showing a reading it couldn't comprehend as it was off the scale. What I am getting at is that it may be getting contaminated with unburnt fuel causing the Lambda to go out of parameters, a symptom of the problem rather than the cause. If it was a coil pack it would show a mis-fire when interrogated. A dirty throttle body just gives general poor tickover. This leaves the air mass meter which might be registering more air than is actually going into the engine, which will lead to over fuelling and unburnt fuel in the exhaust. You could try running it for a liitle while with the air flow sensor disconnected, though this will bring the engine light on, to see if it improves.