What about a GFB DV+ Diverter Valve

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My Golf 5 GTI is now an absolute joy to drive. The car is really strong and stable on the road. I started noticing that some times the car has a bit of lag on the turbo spool up. For a regular person, this would not be a problem but for me, it needs to get sorted out.

I spent a few hours on the net and everything showed towards the Diverter Valve. I originally changed the diverter valve from a Revision C to the latest spec Revision D. The Revision C was a diaphragm type valve where the Revision D was a piston type. The valve that I fitted on the car just wasn’t the fix for the boost problem. The valve just didn’t seem to give repeatable results.

I took out the valve and strip and cleaned it, not a difficult task to do. Nothing I could really see is wrong with the valve. The piston has small holes in it that allow the air\boost to travel to the inside of the piston. There is a lip seal between the piston and the housing. So when there is pressure on the one side of the piston it has the same pressure on the opposite side. A light spring behind the piston then keep the valve closed.

It does not matter what boost pressure you put on the valve it should stay shut, because of the pressure balance.

So what were my findings

I decided to do a blow test on the piston to see if there are any leaks on the unit. I put my mouth on the front the piston and blew. The blew straight back onto my face. The air leaks past the lip seal. I took the valve apart again and found that the lips seal is very hard and it is a very loose fit on the piston. My thoughts were the seal is worn. I went to VW and ordered a new Revision D Diverter valve.

Revision D Diverter valve with leaking seal.

Before I fitted the new Diverter valve to the Golf I tried the same test as I did with the previous valve. The results were the same. This is a really crap design. I took the new valve apart to check it out. The seal was just as hard as the previous valve and the same loose fit. You really have to blow hard on the valve to get the lip seal to do its job properly. Once the lip seal closes up then it does its job properly.

This now means that while the turbo is starting to spool up and the boost is not enough to make the seal work properly the boost you do generate just gets dumped back into your intake. This causes lag.

Getting a proper fix for the problem

Like I said most people will not even notice this, but for me, this was an issue. The car must be crisp at all times. I started searching the net for all the aftermarket DV valves that are available out there. There are some good ones but most of the reviews state that these just don’t functions as well as the standard valve. The standard valve’s response time is so much quicker than the vacuum-operated aftermarket valves.

I then came across a company called GFB which stands for Go Fast Bits. They designed their own version of the factory valve that utilizes the factory solenoid. You buy their kit and then strip your diverter valve and fit their parts to it. They call it a DV+. It was really well priced too. I ordered myself one of the kits. When I received the kit I was amazed by the quality of the parts and how well it was packed.

Here is a link to the kit:

GFB DV+ Diverter Valve Audi | VW

Installing the kit & First drive

Installing the kit was a dream, GFB gives you clear instructions on what to do. It takes about 15 to 20 minutes to do the install. It is really easy to do and you don’t need to be a trained person to install it.

I took the car for a drive and was amazed by the increase in response. The car felt stronger even between gearshifts. It comes onto boost so quickly. Nothing like before. It was like the car was completely transformed. This is by far not a big mod, but it feels like a big one.

Conclusion

I must say that I would recommend anyone to fit a GFB DV+ unit to their car if the car has an electronic diverter valve. Most manufacturers use the same make of electronic diverter valves these days. Go Fast Bits has replacement DV+ kits for most of them. Once fitted you may hear some extra sounds from the turbo that give you that more sporty feeling in the car, but that is just because of the way the unit functions.

Here is a link to this unit:

DV+ Performance Diverter Valve T9351