Mk V Golf 2.0 GT TDi PO299 Turbo Charger Low Boost Fault Code

[Perkster24]

Hi All,
A couple of weeks ago my 09 plate Golf went into what I now know to be limp mode i.e. reduced power with the flashing glow plug symbol coming up on the dashboard. It generally only occurs if I exceed 65mph on an incline. Driving around town all is fine. PO299 comes up on the fault codes. Two of the glow plugs also came up as faulty but I've since had them all replaced to no avail. Engine photo attached.

Having searched PO299 on this forum it seems that it could be due to all manner of things i.e. vacuum valve, turbo actuator, N75, inlet manifold, holes in pipes etc. I'm hoping it hasn't got anything to do with the actual turbo as this looks like a mega expensive replace!

Does anyone know of any reputable garages/mechanics in the Maidstone, Kent area who could reliably diagnose. I'm not really into messing around with cars and don't have the knowledge/expertise. I'm a bit wary of main dealers and their prices having heard a few horror stories.

Cheers

[j_mack]

It was a hole in a pipe on the gti for me doing exactly this, hard to diagnose though what it actually is... a couple of the hoses looked rubbish on mine (all cracked and crazed) and I replaced them.. problem solved


Sent from my iPhone using Tapatalk

[Perkster24]

Belated thanks for the reply j mack. Did yours come up with PO299 or another fault code?

[DMitch16]

The turbos on these engines have variable angle vanes which are moved by a vacuum actuator. The ring inside the exhaust shell of the turbo is susceptible to carbon build up and corrosion. When this happens the vanes do not rotate fully and the underboost code is registered as boost demand is not met. To test this you need to gain access to the rod connected to the lever on the inner side of the exhaust shell of the turbo. A glove would be advisable. Locate the lever and move it up towards the actuator it will be resistant but should move up easily by around a centimetre. If it is very stiff and hard to move the vane mechanism is seized or carbonised. If it moves work it as rapidly as possible up and down as this will help dislodge some of the build up but is only a temporary measure. The turbo will need a proper clean by disassembling it and cleaning the internal VNT mechanism with carbon cleaner and emery cloth. Some copper grease on the contact points of the ring and put it back together will be like new (almost).

One of the most common problems on a VNT turbo powered V dub that invokes limp mode. The actuator diaphragms can also spring small leaks which produce the same code. Testing these involves connecting a hand held vacuum pump with gauge to the actuator, drawing around 10 to 12 psi of vacuum and seeing if the pressure remains stable over the following 30 seconds, if it drops off you have a leak in the diaphragm and need a new actuator.

[makemineamythos]

The turbos on these engines have variable angle vanes which are moved by a vacuum actuator. The ring inside the exhaust shell of the turbo is susceptible to carbon build up and corrosion. When this happens the vanes do not rotate fully and the underboost code is registered as boost demand is not met. To test this you need to gain access to the rod connected to the lever on the inner side of the exhaust shell of the turbo. A glove would be advisable. Locate the lever and move it up towards the actuator it will be resistant but should move up easily by around a centimetre. If it is very stiff and hard to move the vane mechanism is seized or carbonised. If it moves work it as rapidly as possible up and down as this will help dislodge some of the build up but is only a temporary measure. The turbo will need a proper clean by disassembling it and cleaning the internal VNT mechanism with carbon cleaner and emery cloth. Some copper grease on the contact points of the ring and put it back together will be like new (almost).

One of the most common problems on a VNT turbo powered V dub that invokes limp mode. The actuator diaphragms can also spring small leaks which produce the same code. Testing these involves connecting a hand held vacuum pump with gauge to the actuator, drawing around 10 to 12 psi of vacuum and seeing if the pressure remains stable over the following 30 seconds, if it drops off you have a leak in the diaphragm and need a new actuator.

Really interesting response Mitch! I'm having similar issues with my mk5 2.0 tdi, although the fault codes are different (these can be seen on my own thread here Golf 2.0 TDI occasional splutter? (http://www.vwaudiforum.co.uk/forum/showthread.php/182411-Golf-2-0-TDI-occasional-splutter) )
Ive got the car booked into my local garage next week, to have the turbo and egr valve cleaned. I'd be interested to know if you thought that this is a good place to start? I'm about to start a thread for recommendations for an appropriate garage or mechanic in the north west, who may be able to help me with this. Thank you