Hi guys. Just a quick question... my vRS is quite unwell at the moment, but no-one is sure quite why (the problem has even got the guys at the garage stumped!!). There seems to be a problem with the turbo 'over-boosting' and the wastegate is not able to cope; inevitably it leads to a less than smooth driving experience, as the boost is discharged half a dozen times through the rev range in every gear!! After running every diagnostic they can, they are now going to change the entire turbo/wastegate assembly (fortunately covered under warranty!!) Anybody else had similar problems, and am I to expect the new turbo to fail as well? any advice would be much appreciated

Could well be a fault with the N75 valve as that controls rhe wastegate opertation. Had a very similar fault a while back on another members car who was local to me, took a while to track it down.

i'd say teh same as the great man himself, sounds more like boost control rather than a faulty turbo.

In my limited knowledge a faulty turbo will tend to show itself by a noise or lack of boost and possibly even some smoke.

another vote for n75

Would not say smoke on an Octavia

why not? if the seals have gone on any turbo it'll smoke.

Less on a petrol bengie, and no reports of the tubo seals gone

Why less on a petrol?

if the turbo is overboosting, it's practically going to be due to a few reasons:

1, the wastegate is sticky and not allowing the actuator to open it cleanly - this is easy to check for.

2, the actuator is damaged and not able to open the wastegate properly - again easy to check

3, the N75 valve is faulty (or possibly blocked ports/pipework) and not keeping proper control of the wastegate actuator, which is probably the most likely.

other lesser possibilities are ECU fault or N75 wiring problem.

Odds on it's boost control as per others.

As to the "smoking" comments, that depends on the colour of the smoke. IME any turbo engine will black smoke if it's sufficiently over-fuelled; the reason it's more thought of as a "diesel problem" is that it's very much easier to over-fuel a fully mechanical injection diesel (esp a TD) than anything else.

White smoke clouds OTOH are a result of huge quantities of engine oil (like about a pint per mile) being dumped into the exhaust by blown turbo oil seals.

iv swapped out the n75 for a similair issue and it didnt fix it. ending up sticking in a bleed valve to regulate the pressure. all sorted now.

Thanks for the replies guys. Fortunately my warranty company have approved fitting a new turbo to the car, as the garage are still stumped!!!. Hopefully, this should sort out the problems as I think the wastegate and turbo are part of the same unit (??). Not sure about the N75, but if the warranty is paying, the car can stay in the garage until it's fixed!! Does this course of action sound like a possible remedy?

Well a new turbo is a bonus even if it doesnt fix the issue!

Accepted that you've not got a known but unmentioned remap on the car Stig. Can the garage do a power run and see if it's at or below spec? I was just wondering if it was maybe a dodgy remap by a previous owner.