DIY Multi-port Injection Kit.


Go Kart Newbie
Pittsburgh, PA
Disclaimer:- This info is for community usage only. You are welcome to use the information contained in this thread, but I take NO responsibility for any discrepancies, injuries, or catastrophic damage that results from improperly modifying your car. You assume all liability when YOU decide to wrench on your vehicle. Messing around with fuel systems is inherently dangerous and if you do it wrong your car could end up burning up in a fire or worse you could die in a fire. Do your own research before attempting any type of DIY project and confirm part numbers and necessary tools necessary. I do NOT represent any company or receive affiliate compensation from any person or company. I'm just a guy that has spent A LOT of time reading and researching to share my opinions. NO GUARANTEES are offered. To be clear I do NOT recommend making your own MPI kit but if you do, here's how.
I'm doing my best to update this

Run Multi-port Injection on USDM MQB vehicles with "responsibly sourced recycled parts" for those wanting to be green and run ethanol.
- Golf/GTI/GolfR/Tiguan/GSW/A3/A4/S3/A5/TT/Q3/Q5 Basically any vehicle with the EA888 Gen3 Engine that can be tuned.

Existing solutions:-
MPI kit_______________$722-1300
LPFP kit______________$299-1300 (305/450/525/brushless)
Fuel controller 40a __$650-675 (for brushed fuel pumps 450/525)
Cobb or similar______$675

A whopping total of $2072-3725

Why would you want MPI? :-

-More fueling for more power
-Clean intake valves from carbon
-Hybrid Turbo setup
-Because it's OEM in Germany
-Under $600 MPI on OEM parts, opens the door Mo-powa Buhbay

What's the absolute minimum to make this happen? :-
1) Low-pressure fuel rail (OEM used under $80)
2) Fuel injectors (OEM 125cc or 980cc or 1300cc $0-450)
3) 5/16 OEM or 3/8 Oversized T-split ($12)
4) Hose clamps ($12)
5) Wiring harness (DIY cheap)
6) Modifying intake manifold ($8 drill bit and $5 for socket)
7) Tune to activate the injectors
Open source tuning or the usual suspects to activate this for as little as $150

Parts list:-
European Fuel rail - 06K133681C, 06L971627M, 06L906031A or similar.
Seat Leon, Skoda, Audi, VW worldwide all use the same low-pressure rail.
Often they come used with fuel injectors, low-pressure sensor, and even wiring, connectors.
2) LP Fuel sensor - (06H906051J) or similar
3) Fuel injectors - Bosch EV14 CKxT 980cc. (0 280 158 040) if you want to use OEM get new seals for them. OEM 06L 906 031A or similar.
Don't buy counterfeit injectors from sketchy places. Unfortunately, there are TONS of these being sold super cheap because they are fake. Often come with Bosch Jetronic to OEM. They will leak, they can stick wide open.
4) LP fuel pump/kit - Walbro 305 (F90000265) or Walbro 450 (F90000274) or Walbro 535 (F90000285) or full drop in replacement RS3 Fuel pump brushless. (Open source community has accomplished this)
If you want to run 980cc injectors or higher you will need a fuel pump.
5) 5/16 T-split or larger
6) 5/16 fuel hose or larger
7) Hose clamps
5-6 ECU pinned wires - Repair wire
J623 (105pin)/ J283 (91pin) ECU connector with a few inches of wire. (4H0906971A)
Your best option is the entire connector and just de-pin it. 2011->2018 VWAG should work.
9) 3pin D connector (4D0971993)is a fairly common connector in late 2000s Audi/VWs. I managed to find 2 at the junkyard
10) 8pin D connector (4H0973714B) is optional, you could just bypass this connector. $8-18
11) 3pin connector (4F0973703) Male & Female to manifold flap control. Also listed as PDC sensor extension
12) ATC fuse terminal Easily sourced from any 2000-2018 VWAG vehicle fusebox
13) Threaded Insert Kit I used this but there are plenty of options.
14) a tune
15) Odd and Ends-
M6x1x40mm bolts (2)
Drill guide
Fabric wiring loom wrap
14 gauge wire about 4 feet - $4
20 gauge wire about 30 feet- $15
EV14 to OEM 2 pin $0-30

Tools List:- (*)optional
VW depinning toolset
Hand drill
7mm drill bit
Wire stripper/crimper
* Crimper for VW connectors
Channel-lock plier
Needle-nose plier
* Heat gun
1/4 drive socket driver
3/8 drive socket driver
T25 bit
T30 long reach or bit with extension
7mm socket
10mm socket with extension
13mm socket
17mm wrench or crowfoot
21mm wrench
10mm Triple square
Pick set
* Flashlight
* Magnet reach tool
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Go Kart Newbie
Pittsburgh, PA
Building your own Harness:-
VWAG lists wires from ECU as 1mm or about 20 gauge AWS
The power wire running to all the injectors comes from the fuse box. Based on what others have done I went with 14 gauge wire for this.

[This picture needs redrawn, LP fuel sensor needs 5v and injectors are getting 12v on their circuit. Doing this correct has proven difficult. Stealing from the 5v flap control sensor cause CELs so I went with a dedicated 12v DC to 5v DC convertor. ]

You have a wire that runs to the low-pressure fuel sensor Pin 50 to D-clip pin 2 and one that controls the manifold flaps Pin 71.
You simply need enough wire to reach from the ECU connector to about the top of the left side of the intake manifold. Follow the path of the car's wiring harness.
For my GTI I remove the air intake box and that's enough I can measure to run the wires. You will need 5 or 6 wires 18-20 gauge depending on how you want to make your harness. 6 wires for integrated ethanol sensor if you want.
Once you have cut your wires, it's simply connecting pins onto the ends of your wire. Solder seal connectors work really well.
You can tidy up the cables with fabric adhesive and split loom or PET sleeving. I used Fabric, then PET with heat shrink on the ends.

Making your own Drill guide:-
Looking at the injector itself we can see that it is around 13.2mm with an o-ring to compress and seal the gap. In reality, it's about 14mm inside the injector hole.

After a lot of trial and error, I have found a 9mm deep socket from Home Depot that fits very tightly in the injector hole with 1-2 pieces of masking tape wrapped around it. You're looking for around 13.90mm in diameter. The inside diameter hole of the socket is about 7.5mm leaving a little wiggle room. This should be good enough if you are careful. I did pretty well, only have a small boost leak around injector #1 with used seals. New seals addressed this issue.

The Install:-
I'm not going to go over every step or the entire installation of Multi-port injection because I feel it has been covered here, here, and here.

useful tuning info
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Go Kart Newbie
Pittsburgh, PA
Update. If you are not seeing enough fuel flow you can carefully drill out the OEM fuel rail inlet a couple sizes larger. I can't remember exactly how much I opened it up but you can see a fair amount and it will hold. Same can be done for the injector outlets


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Autocross Newbie
Roswell, GA
2016 GSW 1.8tsi auto
OP are you a 1.8tsi? GTI ? R ?


Autocross Newbie
Roswell, GA
2016 GSW 1.8tsi auto


Go Kart Newbie
Pittsburgh, PA
Getting close. Wiring needs tested and tune activated.


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Go Kart Newbie
Pittsburgh, PA
Ready to deliver!


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Passed Driver's Ed
According to VW i-wire, the fuel injector power is spliced into the same power as the cam shift actuators FYI.