OEM management wiring: 1.8T => Mk2 harness install FAQ

Thanks dude, I'll try it out today and see.

 

I am going to fit my 1.8T in to my new Mk3 VR6 I just bought. My engine is an AUM code but I have got hold of an AUQ 180bhp ECU that has had Immob removed.

I only just completed an AGU in to MK3 this weekend and wasn't too bad but this thread will make my conversion even easier I think. I will try and document as much as I can!

Has anyone mounted the FBW pedal assembly yet?

 

do mean dbw pedal

 

Hi guys, been getting on with my conversion recently and am getting there slowly. Engine is in now and will finally be doing the wiring in the next couple of days so will post up here when that is done.

With regards to the pedal no, i havn't mounted it yet, that is another job for the coming week. The best pictures i have seen of how someone has mounted it were in mush's thread over on e38.







Goodluck everyone!!

 

Excellent, I will go have a look for his thread too.

 

Hi johnny. Yea those particular issues were ones which had me baffled for a while too. I came to the conclusion that there is no way that the ecu can know whether the pump is there , only whether the relay was there. So i simply removed the pump wires and left the relay in. The insufficient flow code i believe is triggered as it runs a test cycle sometimes when stationary which should cause a lean lambda condition however if there is no pump this will not happen and so triggers the code. That is my understanding anyway.

As far as the reverse light switch, yea cheers for that , i realised what the wires were for shortly after posting all the info, the other is for the starter. However i have not updated.

I will try to take some pictures tomorrow of how i have done the loom as i finally got around to wiring it all into the car today.

Cheers, James

 

It is a bit complicated and it relates to the calibration settings but I will try to enlighten if I can.
During a cold start and at certain engine temperatures the certain engine controllers will retard the ignition to put more heat into the exhaust and use a cold start table for lambda to richer the mixture. By injecting fresh air into the hot and rich exhaust a thermal reaction is initiated and the catalyst can light up and stat converting NOX, HC and CO.
The injection of this air is done by the Secondary Air Injection pump.
In order to diagnose if the SAI system is actually running two checks can be initiated by the ECU. A passive test, where, just after engine start, the SAI air mass is measured and referenced using the front front lanbda sensor. Having a planer sensor ( wide band) enusre that lambda mesurements can be made just after start. 1.8T engine have this type of sensor as std with a catalyst monitor 2 step sensor at the rear of the cat.
The other test is an active test and is done during engine idle while the engine controller looks at and expected lambda deviation when the pump is triggered.
If the pump down not run then the expected lambda deviation, in the case of the active active test or the case of the passive test the SAI air mass = reference air mass, then a fault will be set with appropiate path to be read by a scan tool.
I really do not know how installing a resistor, to replace pump load, between terminal 30 and earth will change ecu settings and inhibit this fault based on logic.

 

Hi everyone. Thought i had better update this since i have now finished the wiring. I didn't take nearly enough pictures whilst doing it so i must apologize for that however i will attempt to explain my process as best i can, feel free to ask any questions about anything which is unclear.

To start with, the majority of the connections required for the power in both the t14a and t6 connectors can be found on the T5 connector in the scuttle on 90 spec mk2s. The 5 wires of the t5 connector come from the g1 connector in the fusebox.

T5 pins are as follows
1. Live feed for lambda sensor (red/white) connects to g1/8
2. Fuel pump relay earth (yellow/red) connects to g1/3
3. Starter terminal 50 (red/green) not used in conversion
4.Digifant relay switched live (yellow/black) connects to g1/10
5. Switched live for injectors (red/black) connects to Z/1

The other main connectors we will be using are the two wires which previously connected to the coil.

1.Switched live feed (black)
2.tacho feed (red/black)

The other connections are either added to the fusebox or already existing and i will explain these later.

The pins i eventually used are nearly the same as i posted before except that i used the standard mk2 water temperature gauge wiring along with the previously posted water elbow and a minor change to one of the live feeds to the T14a connector.

T6-brown connector
pin 1 -black or black/purple 15 amp fused switched live 15 to ecu T121/3 (g1 pin 4, needs fuse)
pin 2 - purple/white ecu T121/65 to fuel pump relay earth (g1 pin 3)
pin 4 - red/green 20 amp fused constant positive 30 to ecu T121/62 (Y pin 4, needs fuse)
pin 5 - blue/yellow fused 10 amp from fuel pump relay (g1 pin 10, needs fuse)

T14a - 14 pin connector near battery
pin 5 - red/purple 10 amp fused switched live to injectors (183) ( Z/1)
pin 6 - yellow/black fused 10 amp from fuel pump relay (g1 pin 8, needs fuse)
pin 7 - brown earth (204) (197) (Earth to chassis or battery -VE (Edit by mat-mk3) )
pin 9 - brown/white earth for senders (G1 pin 6)

T10W -White connector
pin 4 - white/red ecu T121/39 to clutch pedal switch (Clutch pedal switch in car)


T10 Orange
pin 1 - grey/white to ecu T121/43 (229) ( diagnostics K diag port)
pin 2 - green/red to ecu T121/81 (Tach signal from ecu via tach adaptor to G1 pin 12)
pin 6 - blue/white ecu T121/54 to speed signal in dash wiring (Hall speed sensor on clocks W pin 1)


Using the wires from the T5 connector and adding the 2 earths for the T14a seemed like the easiest option for me so i made up 2 4 pin plugs to connect the mk2 harness to the mk4.

Plug one replaces T6 and has the following pins
1. g1/4 (switched live to ecu)
2. g1/3 (fuel pump relay earth)
3. y/4 (constant live to ecu)
4.g1/10 (switched live feed for sensors)

to the corresponding pins from T6 in the mk4 harness. Pins 1,3, and 4 needed to be fused so i used the fuse and relay holder from the mk4 as i already had it and wanted to hide the relays away under the dash anyway.










Plug two contains the feeds to the other harness which would previously have been via the T14a connector.

1. Z1 (live feed for injectors)
2. g1/8 (live feed for n75 etc)
3. g1/7 (main ecu earth)
4. g1/6 (earth for sensors)

To add this connector i cut the required wires about an inch before the t14a connector and then extended these into the cabin. This allowed me to keep the t14a connector intact so should i decide to use anything else from it later it is still as original. Again g1/8 requires a fuse which i did in the same place as the other fuses. The two earth wires go to pins 6 and 7 of the g1 connector, however both of these will need pins to be added. (will update with part codes)










Thats the wiring of the main live and earth feeds for the mk4 loom complete.
Next we have to wire components such as the clutch switch.

This can be found as a red/white wire on pin 4 of the white T10W connector. I cut this wire at the T10W connector and extended it. I then fed this wire to one side of a vw brake light switch connector(will update with the part code). The other terminal of the connector is connected to the earth terminal block right next to it at the side of the fuse box.


The blue T10h connector only has the connections to the throttle pedal. I cut these and extended them then connected them directly to the pedal connector.


The orange T10 connector holds the last wires we need to use.

1. grey/white (diagnostics k)
2. green/red (tacho signal)
6. blue/white (speed signal)

I have not connected the diagnostics wire or the tacho signal wire yet as i do not have the diag port of the tach adapter so i will explain these later.

The blue/white wire from pin 6 must be connected to the W connector pin 1 on the fusebox. It just happens that the W connector has a short length of yellow/white wire in pin 1 which goes to a single spade connector, this joins it to the radio harness. This is not required in the radio harness so i simply disconnected it here. To make the connection all i needed to do now was extend the blue/white wire from T10/6 and add a spade on the end to mate with this connector.



And there we have it, one completed mk2 20vt loom. I Have taken some pictures to show where i am mounting my ecu and where the relays/fuse box will be mounted. If you have any questions please ask.





I will update with how to wire in the diagnostics port and add the tach adapter when i get around to that. I will also try to add a guide to adding the resistors to the unused items such as the N249 valve.

Cheers, James

 

hi mate when i did mine i found that the temp cluster was to hi if u use the mk4 golf temp sens wot i did was put a 15 ohm risster in the temp wire by the clocks that makes them right

 

Hi joyner, Yea if using the mk4 temp sensor to feed the clocks then it does indeed read high. This was found by other people. MUSH found that fitting i believe it was a 33Ohm resistor that the clock temperature then matched the temperature shown in VAG Com.

I decided to avoid this and use the original mk2 wiring and sensor with a different water flange to accept the sensor. This also means less wire splicing and thus less possibility of joint failures in the future.

Cheers for the post tho, always interesting to hear how other people have attacked problems .

 

how have you all got your rev counter working is it a wire from the altanator as mine is not working but would like it to

 

Rev counter requires a tach adaptor such as the MSD 8920. This is connected between pin 2 of the orange connector(i believe although i haven't done this yet) and G1 pin 12 on a CE2 fusebox. G1 pin 12 is a red/black wire which would originally have gone to the coil on a digifant mk2.

All of the information in this thread only applies though if you are using ME7.x management for example from an AUM or AUQ code engine.

Cheers, James

 

agu ecu

 

wots your car like for putting the power down mine just lights the tyres up to 4th

 

Mines all running on stage 2 OEM management now just a few other little odd jobs to finish her off now (Like an MoT to worry about now...) FBW pedal fitting was a pain in the ass as everything has to some out to remove the old cable pedal
Not a job i wanted to do lol mind! wish i'd uses an older cable throttle set up but i'm assured its better so i've perserviered!

 

Hi guys, just to let you all know i now have the engine running and it started on the first turn of the key......once i realised that i didnt have the fuel pump relay pushed in far enough. So this at least confirms that the wiring methods i have set out here work.

I have still yet to wire in the diagnostic port to check for codes however i will do that soon and report back.

I have hundreds of pictures of the whole 20v swap so i will try to post a full write up of everything soon.

http://s114.photobucket.com/albums/n268/joe_of_death/20VT%20Golf/?action=view&current=P1080063.mp4

 

Don't be shy about getting up the build thread

 

Will be interesting comparing notes once we're both up and running i'm not far from completion, not sorted water temp/tacho yet but she runs a dream. i fitted my odb port in the glove box though i've not checked for DTC's yet. getting my boost pipes welded up at present now they're finalised etc. Finally sorted an ibiza cupra stubby master today too to replace the 16v item 80 from GSF but well worth it! what have you dont about oil pressure sensor wiring btw?? loving the pedal box mod btw!!! i made an alloy bracket which mounts of 3 existing bolts on the bulkhead just replaced them with 3 longer bolts and secured the bracket with nylocks. different means to the same end i guess

Good luck with the project and look forward to your updates!