*Manual for electric diverter valve on 1.8T*
Hello all,
Since the instructions for installing an electric diverter valve are very popular in the German TT group, I would like to share them with you here as well.
First of all: I do not take any liability for possible damages, this instruction is only for information.
Important: This is no "N249 delete instruction". The original control function is completely preserved, but the complex vacuum control, which was necessary at that time, is omitted. Instead, an electric DV is used, as was the case in later VAG models.
What are the advantages of the conversion?
- Reduced complexity of the vacuum control
- omission of the N249 incl. vacuum accumulator -> cleaner look
- Orig. DV often opens from 0,2bar boost pressure unintentionally
- faster control behavior, thus significantly improved response of the engine
- improved durability
- total costs under 70€
What are the disadvantages of the conversion?
- Possibly N249 error code with BAM engines (cause still uncertain?)
- Installation at BAM only possible with DV relocation kit (lack of space)
- Possibly larger pressure peaks at load change than with series part - I'll try to verify this with logs
- Legality uncertain, may not be allowed (?)
A Pierburg valve is used, which is normally used by Fiat / Alfa. No adapter is needed, it is a single part, so no leaks can occur on the DV itself.
The connection diameter of 28mm is slightly larger than the original (25mm), in the rubber intake hose fits without problems, with silicone I had to press a little.
I recommend to buy a meter of vacuum line (3-4mm inner diameter) to be able to route the new lines. Alternatively, something can be built from the old lines, then you should work especially carefully when removing.
Installation:
(This manual is for the European / German TT, US spec TTs have N249 on the cam cover, but technically it’s the same)
First we have to take care of the holder of the control valves N112 and N249 in front of the intake manifold. The N249 (German driver's side) can be removed along with all the vacuum lines there. The vacuum reservoir on the valve cover is also removed in this process.
Two new vacuum lines are then installed:
N112 to secondary air injection valve (to the "right" in the photo).
N112 to intake manifold (on the photo to "top")
The final lines and valves in front of the intake manifold can be seen in the attached photo.
The e-DV is mounted in place of the original DV. The "left" connection in the photo goes into the pressure side, the "upper" connection to the suction side.
Note: the DV apparently works even if you install it upside down, but it was designed by the OEM to be installed as previously described.
Then follows the electrical connection of the new e-DV. To do this, the connector that was previously attached to the N249 is connected to the e-DV using adapter cables from the connectors listed.
I have already ordered the two plugs with cables and crimped them watertight, so the adapter cable, which is about 60cm long, easily reaches from the intake manifold to the intake hose.
The electric DV is now driven in Germany by many TT owners, a real plug and play solution that fixes some problem areas.
