1.4 TSI shudder & loss of power

[Woo]

Hi all, I've hunted through posts and found references to "shunting" and faulty valves, but not an exact description of the problem I have. If the problem is covered somewhere then apologies in advance:

I bought the car, a 2008 GT Sport 6 speed manual with 52,000kms, just over a week ago so it's still under full Dealer warranty for 3 months. Under normal acceleration it shudders quite badly as it switches between supercharger and turbo (boost gauge drops then climbs again, assume this is the point turbo cuts in). This may be normal having never driven one of these new. You feel the change in the form of massive power loss for half a second or so and the exhaust note and engine noise disappear then return as the turbo kicks in.
The next problem is that there are points while driving (usually when car is warm) that it feels like neither the S/C or Turbo are working and acceleration is almost non-existent. This might last 1minute, then it goes back to being normal (with the rough change between S/C and Turbo while accelerating) no particular point in time, tonight it was in 3rd gear while I was in traffic, other times it's happened on the highway in 5th or 6th when I've accelerated to increase speed.

Like I said, I bought the car a week ago, have driven it for 1500kms and know very little about the engine. Before this I had a v5 Bora. Some help would be appreciated.

[gldgti]

Doesn't sound 'normal' to me. Perhaps there is a boost pressure regulation problem somewhere. That engine has a very complex induction system (ofcourse!) so it would pay to get someone to take a look at it who is familiar at least with the setup. I can't recommend anyone unfortunately.

general things that spring to mind that could cause faults similar to what you have described are faulty wastegate actuator for the turbo or perhaps an EGR valve problem.

If you have a dealer warranty I would think give them a shot at diagnosing it.... you never know, they might get it right.

[Woo]

Thanks gldgti, I took it to a local VW service centre today and asked him to check for codes. N249/P2261 came up, which appears to be related to Boost Pressure Control Valve and a code for "Coolant Fan Control Module 1". Have got it booked in at the dealer on Tuesday for replacement/repairs, I'll see how they go.

[piper26]

Mate n249 is your turbo recirc valve. You more than likely have. A faulty valve.

With the kms you have and having only just bought it i highly recommend replacing your spark plugs And check the vacuum lines between turbo->n75 & n75-> wastegate for any splits as these are commonly damaged when plugs are replaced.

Hope this helps

[Mattlock]

The shunting you're describing is worse than in my GT. Mine was fine when cold but as soon as the car warmed up, the turbo failed to cut in. I got s/c boost all the way to 3500rpm and then nothing.

VW re-designed the N249 valve to stop the problem in future. You'll probably need the N75 replaced too to fix it.

As piper26 said get the vacuum lines checked too and 60k is the right time for new spark plugs as well.

[Woo]

Hi all, thanks for the replies. As it turns out, there is a bit more wrong than the fault codes showed. Apparently once they got my car apart today, they realised there was a timing chain issue which was part of a larger recall at some point. The car now has the sump and timing chain removed and is waiting on parts from overseas to fix it. Over the phone the tech felt it may take a week to repair this fault, along with the initial turbo/supercharger issue. The tech was really apologetic, knowing I've only owned the car less than 3 weeks. With timing chain and boost valve issues resolved and 60,000km service performed, is there anything else I should be looking out for with this engine? BTW the 60km service has already been done, it was done at 48,000 because time rather than kms dictated that it needed to be done.