On turbocharged engines, like the EA888 found in our Mk7 GTI project, a diverter valve serves the purpose of releasing turbo boost pressure when the accelerator is released. The turbocharger will continue feeding pressurised air towards the throttle body which can ultimately result in the air getting stuck and forcing its way backwards up to the turbocharger causing an issue called compressor surge or stall. This causes damage and reduces the life span of the turbo.
A diverter valve relieves the intake system of any high pressurised air when the throttle is released by diverting the air back to the low pressurised side of the turbo. The Mk7 doesn’t suffer as badly as its predecessors. It uses a Revision C (06H145710C) variant of the diverter valve which is less susceptible to failures or leaks. But as with most OEM parts, there are better versions available.
GFB DV+ T9351
Go Fast Bits offer the DV+ T9351 which is an upgrade kit that partially uses some of the original diverter but upgrades the internals to improve performance.
The Go Fast Bits kit contains metal components that upgrade the plastic parts for better reliability and strength. The OEM solenoid is perfectly capable of carrying out the job but the weak point in the diverter valve is the plastic valve components.
The kit contains everything you need to upgrade the plastic components to metal components, some revised springs and extended bolts since the overall length of the diverter valve increases.
Fitting the Diverter Valve – GFB DV+ T9351
Begin by removing the intake hoses and the intake elbow. This will expose the diverter valve.
Remove the connector from the diverter valve. There are 3 bolts that hold it in place. Ensure the bolts do not fall when removing them. Remove the bolts and then slide the Diverter valve away from the turbo.
The diverter can now be split ready to be upgraded.
Start by removing the OEM plastic valve and removing the spring.
Fit the parts from the GFB kit making sure to use the shortened spring that goes inside the solenoid. Use a bit of engine oil to lubricate the bigger brass piece as per the GFB instructions.
There is a dimple and a recess that need to be aligned. Once aligned the two parts can be pushed together leaving an upgraded diverter.
Refit the diverter to the turbo using the extended bolts. It helps to fit them by hand first before using tools to tighten them. Refit the connector and with the intake pipes refitted the GFB DV+ is now installed.
GFB DV+ T9351 Verdict
The initial noticeable difference is more responsiveness on throttle and the car pulls harder than it did with the original diverter valve on. Between gear shifts, the car gets back on the power faster than it did previously. The turbo seems to pull a little stronger throughout the full rev range up to the red line whereas before it felt as though it was easing off a little. I have no reason to believe my factory fitted part was underperforming. There were no indications to suggest so. The DV+ has definitely made an improvement on the OEM part and with that being said I’d highly recommend it, even more so if you’re running higher power than standard.
Fitting instructions can be found here
Product link – GFB DV+ T9351
Further information on Diverter valves in the EA888
OEM Mk7 GTI part number: 06H145710C
Video guide for fitment of a similar part: