MK2 GTI 20v Home build - Putting it back together

Coolant sensor goes faulty it over fuels. should be able to see the temp on you obd reader think they end up going -20 on the reading

 

I think I might have found the issue. I have an earth connection mid way between the loom connection and the fuel pump relay. So I think that might have been causing issues. Have labelled it and will plug the loom back in tonight to check if that solves the problem

 

Hope so mate.small things always the biggest problem it seems.

 

I have edited this post a few times, but now that the engine is up and running, this has everything i need to get my AGU running. Thanks to John Newman AKA RubJonny for the help as always!


So i have decided to just write out all the connections for the AGU to CE2 here, it will be easier to spot the issue and might also be useful for others:

I run a separate relay to power the ECU which is a 53 Relay, it is not the prettiest, but it works and its solid.




Z1 - to Engine loom connection pin 5
30 - to fused ECU relay Pin 30- this then powers ECU pin 3 - so Permanant Live as its a live fed before the relay takes an action?

relay Pin numbers
30 - fused Live from Fusebox Live 30
85 - Earth - Engine loom Pin 9, Earthed near the fusebox
86 - Goes to G2/4
87 - Goes to engine loom pin 8 and also ECU Pin 1



G1/1 - Empty
G1/2 - outside air temp sender ground
G1/3 - ECU relay power to ECU pin 4
G1/4 - Empty
G1/5 - Ground to Cylinder Head
G1/6 - Empty
G1/7 - Empty
G1/8 - Heated Oxygen sensor power - this merges into a single feed for my MAF and O2 sensor power and engine loom pin 6
G1/9 - Empty
G1/10 - Empty
G1/11 - Blank
G1/12 - Tacho input

G2/1 - Oil Temp (to a sender on the oil cooler/filter housing part number 049919563B)
G2/2 - Outside Air Temp Sender
G2/3 - feeds engine loom pin 4 (should be coolant temp sender)
G2/4 - feeds to ECU relay 86
G2/5 - Empty
G2/6 - Empty
G2/7 - Empty
G2/8 - Empty
G2/9 - Empty
G2/10 - Oil pressure (High Oil Pressure Switch to a sender on the engine (056919081 - oil pressure switch, 1.8bar, white))
G2/11 - Engine loom pin 1 - (Low Oil Pressure Switch (028919081H - oil pressure switch, 0.24bar, blue ))
G2/12 - Empty


T14a connection - Engine loom (agu)
1 - G2/11 (Low Oil Pressure Switch) - this is a black wire on the engine loom that has goes to a low pressure sender
2 - Empty
3 - Empty
4 - G2/3
5 - Z1 Power
6 - G1/8
7 - Earth for coilpacks - To the battery
8 - Coilpack Power - to ECU Relay 87, The 87 connection also runs to ECU Pin 1
9 - ECU relay pin 85 - Its the Earth for the Coolant Temp Sensor, can go to any earth point.
10 - Empty
11 - Empty
12 - Empty
13 - Empty
14 - Empty

ECU connection:
1- Live from Relay pin 87
2 - Earth - just needs to be a solid earth point
3 - Permanent Live relay pin 30
4 - G1/3
6 - Tacho - rev signal
12 - MAF Pin 3
13 - MAF Pin 1
19 - Kiline for OBD Port
25 - 02 sensor
26 - 02 sensor
27 - Lambda Earth - can go above fusebox

 

Where about a is the Crank sensor

 

car was all fine and running when i pulled the loom previously though, can imagine it would just break when laid up?

 

About right for this year.hope it gets not to much of a pain to find it does it even try to run

 

yeah on occasion it will for a few seconds. this is why i think its a wiring issue. Bad earths can play a big role in intermittent running

 

Got some errors on a scan now i can connect to VagCom, maybe my wiring is ok and i just have the issue with the throttle, i knew it was not making the noise like it used to. I did replace the clip for that connection, so likely got a wire the wrong way around?

17953 butterfly valve control malfunctioning
17973 butterfly valve control unit -J338 lower notice one does not reach
00670 - Throttle Position Sensor (G127) 06-00 - Signal too High
16507 butterfly valve potentiometers signal too largely

 

Hope this sorts it mate

 

throttle body resolved, 2 of the tiny cables were reversed. Now it sounds and acts as expected...

still no fire up though witht he MAF in...this might be down to none of the pipes being connected up with clamps, just loosly on and loads of VAC leaks..

With the MAF off, it ran!

 

Little update in that with the MAF on today it started up first time

 

Grrr technology!
Certain gremlins are a nightmare, let's hope its sorted mate.

 

Yeah ECU relay, not sure why i was calling it the fuel relay. Just confusion i think.

Thats good info John, thank you again! will updaye my list above. i'm sure i'll need to re-visit it again at some point

 

Well the car is running reliably so back to wiring and just making that work in terms of routing a little bit better.

The ecu to engine loom is fine but with the way i wanted to route the ECU relay to engine was a bit short. So i've extended it by about a meter or so, this should give me the slack i need to run it properly.

Injectors have been swapped over
Driveshafts in
Intercooler plumbed in
Battery relocated to the boot and working
Live and Earth feeds to the battery to the boot

 

Getting there then Craig, it's all the little bits that take the time, and hiccups along the way dont help at all.
Keep it up mate.

 

Been doing some bits but forgot to take many photos.

Fusebox to engine loom extended just to make it all much easier to route internally.
Engine loom looks much tidier now
Battery cables ran but will need to decide on a new battery and how i'm going to secure it in the boot... i have got a false floor in there at the moment for the Sub, but i won't be running a stereo any more, so might re-make the floor and secure the battery to that.

IMG_20201218_145924 by Laxadams, on Flickr

IMG_20201218_151432 by Laxadams, on Flickr

IMG_20201217_160620_758 by Laxadams, on Flickr

 

Modified the TIP, MAF and intake