126 replies to this topic

[Oscar]

Gazzy hasn't done anything with the 4 plug BG wiring.

So when I get the wiring, I'll have a go at it on my own and put my findings in this thread.

Okay, so I've managed to get the 4 plug 20H ECU diagram and compared it to the 4 plug BC5 20G diagram as good as I can. There are still a few bits that are blank. I'll post up what I have got so far when I manage to get it from paper to PC.

To be perfectly honest, repinning a BG5A loom to work with a BC5/GC8A/B ECU is going to involve so much fucking work that I would honestly recommend replacing with a GC8 loom. If you are hell bent on using the TT loom then I would highly suggest making an ECU plug adapter.

tl;dr I hope you like to play with electrical spaghetti.

[suspect]

Hi guys,

I know this thread is quite old, but hoping someone could help me out here.. i've been reading through this entire thread and looking at so many photos etc. Converting my Legacy GTB (EJ20R) to single turbo.. i've got all the parts etc. but stuck on a few things.

Questions.

1) The intake manifold from the V3/V4 come complete including the wiring loom, should I be using this loom instead of the BG5 one? (I've had a look it does have a few extra plugs).

2) In the uploaded photos is this a sensor? One appears to be a vacume hose or something but the other looks like a sensor or something? (i've put the BG5 one back into the plenum, as the other looks like a hose attaches but never had this?)

 IMG_0469.jpg   211.21KB   15 downloads

Excuse my ignorance..

I've also done the split fuel rail, hope this is right.

[boostin]

That doesn't look like its in the right place. It looks like the valve that's meant to be up in the middle of the manifold. Sensors have wires attached, so that's not a sensor.

[Reuben]

1. It is recommended to use the single turbo manifold loom, it tidies up the wiring for the coil back mod beautifully. If you are not doing the coil pack mod, and for whatever reason want to run individual coils in a wasted spark setup, you must use the TT manifold loom.

2. Yeah, that has a vacuum nipple broken off it, I think it might actually be a filter for a TT vac line, screwed in where your brake booster valve should be.

[suspect]

Ahh.. okay.. thanks guys.

My biggest mistake is when I moved houses i've had all the parts for the single turbo and all the TT ones in a box.. which now I know that I should have label what was from the ST and what was from the TT because it's a nightmare figuring out what is what! :/

Can't seem to find any manuals which cover/diagrams of the intake manifold.







I've done the coil pack mod using the WRX STI pack (as seen) (no wiring has been done as of yet)

[Reuben]

The only wiring you will need to do is splicing in an ignitor somewhere.

Also make sure you sand the paint off the manifold mating surfaces! And get them sanded flat and smooth, taking the manfold off in the car only because a gasket is leaking is a pretty annoying thing to do.

Also also, tidy up the split rail under the BOV return. If you leave it like that, it fouls on the coolant crossover pipe.

[suspect]

Thanks for that Reuben, yeah it's already been sanded off using a glass plate I have, these were just taking off my phone about 10:00pm the other night hence the poor quality.

I was thinking that after I had put that pipe on, that I would probably need to take this off for the wiring loom also, so will do this at the same time.

[alithomson]

ok again i know that it probably hasnt been done as by the looks of things its a pain in the pisser but does anyone have any info on a bd5a ecu to a newer on. I have a 7c in the car at the moment at am hoping to get a 4g ecu and doctor it eo that i can re map it first of all then do a single turbo conversion.

[Reuben]

What is a 4G? IS it twin or single. You can't map a twin ecu to run single, you can't map a single ecu to do twin.

[alithomson]

A 4g is from the newer model twins.bout the 98 version 3s i think. and they can be re mapped with a daughterboard.There is a guy on the uk leg forum that has one in his single turbo conversion and he got it re flashed to an impreza map after he had his conversion finished. He had a daughterboard installed and it re mapped prior to his conversion.Apparently it can be re pinned with using an adapter from the old 4 to the newer 3 plug ecu.

[Familyman]

Could you please post up a link for that. I am very curious.

[DacerX]

Sounds like alot of fcking around to me, just get a aftermarket ecu or a single TiVo ecu as this thread suggests and done

[Reuben]

If you mean model year 98, that's Version 5, where they went to phase two, those ECU's are def more tunable that master-4 V3 and 4 ECU's.

But yeah, that is a lot of fucking about, what's wrong with just doing the wiring for single turbo, and the conversion at the same time like everyone else has?

[DacerX]

Amen brother Reuben

[alithomson]

i would do but as far as i can work out the current ecu wont work unless its re pinned some way or another, either for the single turbo early impreza maps or the newer twins. Unless anyone here knows any different, thats kind of why im stuck at the moment i cant find any concrete info relating to the bd5a

[alithomson]

Could you please post up a link for that. I am very curious.

I will try and find the thread from the uk legacy forum.

[suspect]

Soo.. finally gotten around to putting these photos up.. using the WRX loom, there's a few extra plugs on this which unsure where they go.. if anywhere.







Hopefully i'm not missng anything..

[h8wrx]

im nearly finished my conversion, and need help with one more thing, the 02 sensor, my wagon(garage project to follow) 97 GT
has what it seems 3 02 sensors, ive installed my sti v3 eng in and my new 02 sensor is now on top of the siamese down pipe,
question is which 02 sensor/plug do i use??
cheers

[boostin]

The one from the left hand manifold/up-pipe.

[h8wrx]

The one from the left hand manifold/up-pipe.

The one that goes into the passenger guard?