AGG Engine Conversion - Electrics

[StoneRoses]

Hi
I’m a long-term Aircooled guy, who right now is outside my comfort zone whilst helping out with a T3 engine conversion. So this post is very much a reach-out to the global water-cooled community, cheers in advance for any assistance.

We’re replacing an end-of-life 1983 petrol DG engine with a 2.0ltr AGG engine donated from a Golf Mk3.

We’ve sourced most the parts needed for the conversion, and the mechanical side is progressing fine, not least due to some invaluable knowledge gleaned this forum – thanks.

My challenge is on the electrical side of things…ECU’s, MAF’s, lambda probes, etc., all new-age wizardry as far as I’m concerned  I’ve done a lot of research on this group and elsewhere, and am learning loads, but am still struggling with the ready-made loom we inherited for the conversion. I believe was extracted from the donor Mk3 and modified specifically for the conversion.

I’m struggling to understand what some of its connections are for, e.g., what sensors and how/where it integrates with the T3 wiring. With reference to below picture, my understanding and questions are thus:




A: 3 brown, 1 brown/white > earth
B: > ECU
C: blue, brown. OBD port ?
C1: brown, blue/green. Connects to case, which sensor is it for ?
D: Relays (fuel pump and ECU)
E: Engine
F: single red/green , female spade connector. Connects to what ?
G: grey, blue, black, heavily insulated, connects to case, which sensor is it for?
H: brown/blue, green/black, orange/red. Connects to case, which sensor is it for?
I: white, yellow, brown, red/white into 4-port connector. Lambda sensor.
J: brown, green, black: three pin connector . Connects to what ?
J2: green/black, single female spade connector. Connects to what
K: 6 pin connection for vehicle wiring. brown, blue, yellow/red, blue/black, green/black, yellow. Integrate by following T3 wiring diagram.
2-terminal male connector block, black, purple/yellow. Connect to what ?
2x 4mm red – solenoid for power.
L: yellow, brown, red/green. Heavily insulated, 3 pin connector. Connect to what ?
M: yellow/white, brown/blue, 2 pin connector. Connect to what ?
 
A secondary concern…is the ECU likely to have issues if a sensor is not present. I.e., is it mandatory for us to wire in Lamdba, MAF, etc. sensors ? Would their absence significantly affect engine performance, possibly even causing permanent damage to the ECU ?

[silverbullet]

Andy at syncrosport will make you a new engine harness, or Elvis Summers (find him of facebook) or Jamie Lockyer.

Any of them may have made your harness, its worth asking.

If you want to go DIY then you'll need a Haynes Mk3 golf book for the current flow diagrams which you can then match up to the T3 wiring.

PS your photo doesnt appear to have uploaded

[R0B]

.

[Aidan]

the picture is on one drive and accessible but doesn't display, here it is




Andy is busy doing his tax return 

[Club Joker]

I think I can offer a bit of help with this:

A: 3 brown, 1 brown/white > earth
B: > ECU
C: blue, brown. OBD port ? Yes
C1: brown, blue/green. Connects to case, which sensor is it for ? May be charcol filter solenoid perhaps?
D: Relays (fuel pump and ECU)
E: Engine
F: single red/green , female spade connector. Connects to what ? Starter solenoid
G: grey, blue, black, heavily insulated, connects to case, which sensor is it for? Knock sensor
H: brown/blue, green/black, orange/red. Connects to case, which sensor is it for? Crank Sensor
I: white, yellow, brown, red/white into 4-port connector. Lambda sensor.
J: brown, green, black: three pin connector . Connects to what ? Coil or MAF?
J2: green/black, single female spade connector. Connects to what. Probably rev counter feed from coil?
K: 6 pin connection for vehicle wiring. brown (earth), blue, yellow/red (water temp?), blue/black (oil pressure on cylinder head?), green/black, yellow (oil pressure by filter). Integrate by following T3 wiring diagram.
2-terminal male connector block, black, purple/yellow. Connect to what ? Probably fuel pump?  Track back to relays to confirm.  
2x 4mm red – solenoid for power.
L: yellow, brown, red/green. Heavily insulated, 3 pin connector. Connect to what ? Coil (I think - mine are green/red, brown, black)  Could also be MAF. Probably MAF given location on loom.
M: yellow/white, brown/blue, 2 pin connector. Connect to what ? Air temperature sensor on air box
 
A secondary concern…is the ECU likely to have issues if a sensor is not present. I.e., is it mandatory for us to wire in Lamdba, MAF, etc. sensors ? Would their absence significantly affect engine performance, possibly even causing permanent damage to the ECU ? Wire in as much as you possibly can. It is all there for  reason.  I suspect that the ECU would default to a limp mode or run super-rich the whole time, if it ran at all.

From memory, I think that most of the connectors were specific to the sensors that they need to plug into, so I would try connecting them and see what fits.  That should massively narrow things down for you.

My conversion thread is here.  Good luck!

[maxstu]

Hi Club Joker,
A quick question for you...or anyone else in the know...
A fellow forum user is part way through an AGG 2 litre GTI conversion. In helping, l have been reading tthrough your conversion.
Would you please confirm a speed sensor is needed for the ECU? And what is the outcome trying to run the AGG without one? Jerky throttle response, perhaps? Or a complete non runner?
Regards
Stuart

[Forden341]

I am running an AGG in my Gipsy and an ABF in my Syncro, both from Mk3 Gti’s. Neither have speed sensors connected and no issues to report.

[maxstu]

Thanks very much for confirming my thoughts.
Likely the MAF or ECU or throttle body worn and giving jerky throttle response.
Regards
Stuart

[Club Joker]

I ran mine without a speed sensor for a bit. I think that the only impact was a slight drop in fuel economy. I didn't notice any difference when driving.

[maxstu]

Thanks for your reply Joker.
The T25/GTI conversion owner drove it yesterday and seems a lot happier with throttle response now. Perhaps now adjusting to a new-ish camper.