RaymondH

I did this last week and it makes a surprising difference. The car runs much smoother and pick up seems slightly improved. I used 5m of 105 amp cable costing £1.50/metre from Demon Tweeks and terminals, heat shrink and crimping pliers from an electrician friend. Took about 2 hours - time well spent IMHO

See http://www.lumine.net/subaru/legacyb4/index.html for piccies and where I got the idea from.

Raymond.

[Edited by RaymondH - 11/2/2001 8:08:45 PM]

Floyd

iTrader: (9)

What's the rational behind this, can you explain further?

F

RaymondH

I believe that it is to do with earthing the injectors properly so that they see a cleaner signal. Presumably the engine earthing could be better and there are stray signals thrown about by the alternator (the radio is better now) so the injectors now get a signal with no interference. I actually did this and jumped into the car the next morning having forgotten about it and had only gone a few yards before I wondered why it was smoother. A mate who works at the local dealers has been out in it too and noticed the difference. Apparently kits are available off the shelf in Japan. Hokum? I don't know but it seems to work. You pays your money.....

Raymond.

dfullerton

Ahh you know now

RaymondH

Yup. But let's keep it a secret between ourselves.......

JohnD

iTrader: (5)

Might be worth a try. Something to fiddle with on a Sunday morning! WHY is each side of the inlet manifold earthed twice?? after all, it is one casting! Do you think these guys have shares in the cable making company?
I would like to know a bit more on the theory of this.
JohnD

RaymondH

John,

Maybe each branch needs to be earthed separately otherwise the injectors would end up interfering with each other's signals so separate earthing keeps it clean.

Raymond.

AJbaseBloke

hallelujah!

Someone's finally doing it...(well I know some have done it already) AND talking about it

It works, more on some cars than others (but works nevertheless), but the rational is sound: prevent build up of noise in various components, permit the sensors/ecu to get purer signals. Creating "drains" for for the noise also can help with the brightness of headlights, aswell as that nice addition of headroom in the soundsystem.

Enjoy!

GrahamF

I must confess about being a complete sceptic about 'earthing mods'.........until today. Just for the hell of it I found a length of old engine earthing strap in the garage and fitted it between the nearest bolt on the manifold and the battery negative, and bingo, everything seems so much smoother.

I think the main reason is that Subaru don't believe in lock-washers, so the main engine earth (from the starter motor) relies on a steel bolt and plain steel washer into an aluminium block. Probably alright for a couple of years, but then (mine is a MY98) the surfaces corrrode slightly and the resistence builds up. When I checked, mine was showing about 10ohms - not enough to bother the starter much, but probably enough to confuse the lower current things.

So the recommendation is: clean the starter earth and properly earth the manifold. I'm still not convinced about multipoint earthing, though.

Graham

HarryBoy

Star Earthing has been used extensively in Hi-Fi equipment for years to redcue 're-circulating currents' and noise, therefore improving sound quality, so I can see how this principle might work on car electronics as well, I'll have to try it out!

Floyd

iTrader: (9)

I'm with JohnD on this one! I can't see why you'd need 2 cables on the i/l manifold but earthing different components may help.

Afterall I run an EMC laboratory and I know all about interference, emmissions and suseptability! I just didn't think that it would matter that much on a car before.

It may be worth a w/e tinker....

F

scoobystutoo

Hello everyone did the Earth mod yesterday very good its smoother.
But you don't need all those wires, You just need a 105amp wire from the battery to the manifold & one from battery to a good clean body earth. After all the manifold is in one piece
stu

Ed Hodgson

I came across the earthing stuff some time ago on the B4 site. Time for it all to be shot down in flames again!

- In Japan they seem to swear by it, & also claim it helps reduce VOD (Valley of Death) between the sequential turbos on the Legacy.

I stuck some more earthing wires on mine - It's very cheap, & I was curious to see if it would work. to be honest I didn't notice much difference, as I'd only had the car a couple of weeks. VOD seemed to be reduced, but this does vary, depending on driving style etc.. Air temps, petrol also seem to have an influence on performance/smoothness so it's not easy to isolate one factor.

I'll have to remove them when I can be bothered & report back. Won't be for a while tho, as I have an exhaust problem that needs fixing first.

you should find a number of posts from Feb/March discussing this

Ed

HarryBoy

To add a little more intrigue to this subject, I found this ‘thread’ on an Audio message board:

http://www.audioasylum.com/audio/tweaks/messages/45874.html

They are talking about a product from http://www.shakti-innovations.com

Designed to reduce/eliminate RFI from car electronic systems.

Harry.

RON

I did this this evening for something to do, as soon as I started the engine it seemed to be runnig smoother (or was I imagining it?)
Anyway, I went for a drive and it did seem better, who know's? maybe it's not all gumpf afterall!
Ron

Luke

Still the cheapest mod you can make. The right air pressure in your tyres should be free....

AJbaseBloke

Not if u use nitrogen m8!

scud8

iTrader: (1)

With high frequency signals, the EM emissions are proportional to the area of the current loop. So if you provide lots of different earthing points, you allow the current to return on a path close to the signal path, reducing the level of emissions and the interference with other equipment.