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Old 07-13-2003, 03:12 AM   #1
Scooby Newbie
Member#: 38925
Join Date: Jun 2003
Location: seattle WA
1990 legacy wgn
Pig blood for paint

Default Overdoing ground mod will cause it to not work at all!

My freind and I just did the ground rewire/scrape MOD. I found that overdoing your ground MOD can have some negative effects (no pun intended ).

I drive a '90 legacy wgn AWD and my freind has a much cooler/faster '99 RS. We've always complained about both of our cars having way too much hesitaion in weak revs. I came across the ground mod on the internet and decided it was worth a $2.00 try. I noticed that a lot of people complained about the mod not working or making their car run worse, while others raved about the change.

On my friend's RS, we sanded away the paint on all of the original ground connections. The only extra ground points we created were:
1 wire to the underside of radiator holder from battery
1 wire to the intake manifold from battery
BTW: we used Janky (cheap) extension cord for the new ground points. Anyone who thinks paying $100 for wires will benefit them anymore than my $2.00 wires..... well .... let's just say that I have a bridge I would like to sell to you!!

Anyways we reset the ECU and had instant improvement! My freind was complaining that his headlights were too bright! People always flash him thinking he has brights on.

The ease of reving is where you see the most out of this mod. His car now pulls hard to redline without ANY hesitation, even with four fat a$$es in it going uphill. Needless to say he had a big smile.

After an extensive test run, we decided to try and make it better, which we thought required more wires. We put wires going from the engine to other parts of the car in an attempt to completely ground everything. We even placed wires going in between other connectors. We then reset the ECU.
The result? The hesitation came back!
We did a quick roadside wire pull and ECU reset to what it had been when it first worked( OE wires plus two extras).
What do ya know... the hesitation was gone again.
I haven't had time yet to do a step by step elimination of the problem to see which wire/wires did the reversal, but I'm leaning towards the engine to strut tower wires.

I then did all of the above on my '90 legacy and found that overdoing the grounds actually made it WAYYYY worse!!! Just cleaning the OE grounds and adding those two wires made all the difference in the world! Keeping it simple seems to be the best bet for this mod. At least from my experience.

Ohh yeah one more thing, those ragged washer type things Subaru placed in between the frame and the wire contact shouldn't be there. I got rid of them so the wire contact would sit soundly right on the car frame where I removed paint. I know a thing or two about physics, and having electricity run through three different entities of metal (wire > contact > bolt >washer> frame) is very dirty and inefficient. Don't count on the bolt to be able to giv you a perfect flow. Put the wire contact directly on the frame!

So, if any of you have tried this mod without sucess, try what I did and I'll guarantee success. hehe Although my guarantee is void if you go and putting NEG to your POS!

Anyways, good luck! Anyone done this mod to other subie models?
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Old 07-13-2003, 05:57 PM   #2
Scooby Specialist
Member#: 21400
Join Date: Jul 2002
Chapter/Region: NESIC
Location: Seacoast, NH
2015 WRX Limited


i was thinking about the gnarly washers you mentioned. i think subaru uses those to grind through the paint to make a metal to metal ground. ideally i think you would want to remove everything and grind that spot down to metal, the reattach the ground wire(s) without that knobby washer.

i think it would be better contact that way, obviously with grease to avoid corrosion.

i just made my own ground kit from 8 gauge wire and gold plated ring teminals for about $40. i think i had 4-5 wires total, seemed to give something... not sure it was ground breaking but what do you want for $40!?!?

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Old 07-14-2003, 12:17 AM   #3
Scooby Newbie
Member#: 38460
Join Date: Jun 2003
Location: Sydney, Australia.
2005 Liberty 3.0R B
Obsidian Black


You may have been creating ground loops by putting too many ground points on your car. This may create slight voltage differences from each ground point and cause the problem. I'm not sure but this could be causing the problem.

I think the ground to the manifold would help as it is the ground point for the injectors and the spark plugs. As for the ground to the radiator I don't why this would work. Have you tried diconnecting this one to see if it makes a difference for the worse? You may only need the manifold ground as I can see how that may work.
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Old 07-14-2003, 08:53 AM   #4
Uncle Scotty
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Join Date: Mar 2002
OK buy Nates beans


Those 'gnarly' washers are a form of lockwasher. They are there to keep vibration from backing out the bolts.
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Old 07-14-2003, 04:25 PM   #5
Scooby Specialist
Member#: 31892
Join Date: Jan 2003
Location: KC
2004 STi


Another possibility is that one of your grounds was in close proximity to your positive on the alternator.
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