Reply With QuoteExperienced the very same problem - the root cause was the supercharger clutch was slipping when it was warm. Replacement clutch fixed it right up.
Volkswagen Enthusiast
Hi everyone,
About 2 weeks ago my car suddenly decided not to provide turbo boost once it had been driven for about 20-25 minutes. At 3,500RPM, the supercharger disengages and the turbo doesn't cut in. This results is a sudden, noticeable reduction in acceleration and the boost gauge on the dash drops from full boost to about 25%. When cold, it works just fine.
I took it to my mechanic and he ran the codes and it identified an N249 diverter failure, which he replaced with a new part. He said it was a newer revision of the part too. However, the problem still remains, although once in the last 3 days, it failed to have supercharger boost as well.
The fault can be reproduced each and every time and the turbo doesn't return until the car has cooled down.
Interestingly, when it works as normal the car seems to accelerate a bit harder than before maybe as a result of the updated/improved N249.
It's booked in for next week to have another look but I was just wondering if anyone else has experienced similar issues and how easy were they to resolve.
Volkswagen Fan
Experienced the very same problem - the root cause was the supercharger clutch was slipping when it was warm. Replacement clutch fixed it right up.
Dub Crazy
VWwA Super Moderator
Why would the supercharger clutch stop the turbo from working???? I am not seeing that....
Volkswagen Enthusiast
Yeah, I was in the middle of saying the same thing!Originally Posted by h100vw
The supercharger works fine. It provides boost up to 3,500RPM regardless of the operating temperature. The boost is missing from 3,500 upwards.
I wonder if I have a vacuum hose not sealing properly and expanding when hot.
MY08 Mk5 GT Sport - sold
MY14 Tiguan 118TSI - sold (Mazda3 SP25GT in its place)
MY16 Golf 7R: sold (Caterham Super 7 and Hyundai i30N in its place)
Volkswagen Fan
I know. I said the same thing at the time. the two are not connected. dead spot after supercharger should disengage.
the invoice for repair cited a replacement clutch for the supercharger and the problem was gone! go figure.
Volkswagen Enthusiast
How odd. Every time it's done it in the last 2 weeks, there's been no dead spot, the turbo is just MIA! However on the drive home tonight, I had a dead spot; no boost between 3,500 and 4,000 and then it suddenly came back and surprised me and nearly caught me out!
You could be right...
MY08 Mk5 GT Sport - sold
MY14 Tiguan 118TSI - sold (Mazda3 SP25GT in its place)
MY16 Golf 7R: sold (Caterham Super 7 and Hyundai i30N in its place)
Volkswagen Enthusiast
Out of interest, was that all that was changed? Do you mind if I ask How much it cost to fix?
MY08 Mk5 GT Sport - sold
MY14 Tiguan 118TSI - sold (Mazda3 SP25GT in its place)
MY16 Golf 7R: sold (Caterham Super 7 and Hyundai i30N in its place)
Volkswagen Fan
Try the N75 valve also, I had the same symptoms, changed both and all was sorted (N75 should be well under $100)
MY08 Blue Graphite GT TSI DSG
Volkswagen Enthusiast
OK. So what does that one do? I assumed it was the diverter for the supercharger and as it is working fine wouldn't need to be touched.
The only fault code when it did it before the N249 replacement was for the N249. Are the codes cascaded with the most important only showing and secondary codes suppressed?
The mechanic is going to take another look at it on Tuesday so I'll report back after that.
MY08 Mk5 GT Sport - sold
MY14 Tiguan 118TSI - sold (Mazda3 SP25GT in its place)
MY16 Golf 7R: sold (Caterham Super 7 and Hyundai i30N in its place)
Dub Crazy
VWwA Super Moderator
All faults will be held until deleted.
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