"Grounding mod" - Major Improvements!

[91White-T]

I ran some 8 gauge wire, 3 connected to neg. terminal, then one to the driver side strut tower, one to the starter ground, and one to the plug wire bracket bolt on the #1 intake manifold runner.

[NZHall]

What about the ECU itself? Is there anything to be gained from improving the ECU's ground to chassis? Anyone tried it :?:

[Legacy777]

ECU is bolted directly to the chassis. Not much more you can do there.

[NZHall]

OK then...right...

[vrg3]

Well, in theory, you could maybe still benefit from adding a ground strap from the ECU to the engine block... As I wrote above, though, it seems most sensible to add a grounding strap from the oxygen sensor and the knock sensor and take it straight to either another sensor's ground or to the ECU's ground itself.

[NZHall]

I have been trying to sort some frustrating hesitation niggles with my car. Little by little I am seeing improvements and I have to say this forum has been a goldmine for info and advice. So thanks guys.

I have already done the "basic" grounding mod of heavy gauge cable to left + right strut tower bolts, intake manifold, car chassis and engine block to battery negative terminal. Plus, I have very recently installed a new, "white connector" type genuine knock sensor. I have also ordered (but am yet to receive) a new, genuine 3 wire oxygen sensor (Part #22690-AA-090) as I suspect the current one is the original part and as the car has done 140,000 km is probably "lethargic" and contributing significantly to my car's surging and drivability problems. When it arrives I reckon I might be the ideal candidate to run a little sensor grounding experiment for all our collective info. To give some feedback on the possibilities being speculated on in the above thread I'll initially install the new oxygen sensor without any additional grounding cable, and test any changes in the car's performance. Then I'll attach a dedicated heavy gauge ground cable from the knock sensor to the earth mod, and test for any changes there. Finally, a dedicated heavy gauge ground cable from oxygen sensor and its' exhaust mount, via a copper intermediate washer and wire spiral (to cool things down prior to joining the earth mod) and test this with (and without) the knock sensor earth being connected. If I can get my hands on a decent multimeter I'll report on resistance between ECU and both sensor bodies, before and after grounding improvements, and hot and cold in the case of the oxygen sensor and exhaust manifold.
I know our cars are all a little different, but this hesitation thing seems to be an almost universal pain in the ar$e (a$$?) to fix, so I'll try to give objective feedback. Oh, but if it cures the low-mid RPM, light throttle surging my car has you'll hear the yee-haa in the Northern Hemisphere!

Iain

[aspect]

Thought I'd dig up this old thread to keep the discussion as complete as possible...


I just did a grounding mod install, looks exactly like morgies (same wire, same connectors!) BUT because I was late picking up someone, I only had time to attach the line that goes from the battery to the alternator. Instead of attaching to the small clip to the left of the coilpack (mine has been removed) I just hooked the terminals to the bottom-left bolt on the coilpack itself.

Then, of course, there is a shorter wire that runs down to the alternator bolt.

I have not grounded the knock sensor or starter, but have already noticed a difference! The headlights are slightly brighter, and there is much less low-end hesitation. Not bad for some stereo wire ($free) and some ring terminals ($1.20 for 4).

I'm guessing my engine ground and whatnot are limiting the alternator output due to corrosion or similar...my alt has been tested recently and provides tons of juice, but it seemed the car wasn't really working 100% until 3000rpm showed up on the dash.

So, would this help a new car? I doubt it. My car? Big help!

Will install starter/knock ground and post up any effects...

[QuickDrive]

See, this mod is kinda tricky...

Myself.. no noticable differences.
You, tonnes..

Deffinately wierd.

[aspect]

Well, that's actually a good thing, because that means there's nothing wrong with your electrics...

my car w/ grounding = your car w/o grounding

[mhrallyteam]

Mine has BIG hesitation problems, i'll do the mod this week-end, i'll give you guys my results. hope it helps!

[mhrallyteam]

Grouding mod done, hesitation gone. Lights are brighter too. I still have some other thing to change, but grounding definetly works

[QuickDrive]

Well there you have it folks

[aspect]

Grouding mod done, hesitation gone. Lights are brighter too. I still have some other thing to change, but grounding definetly works

Where did you ground to?

[harlock]

Hi guys,
My "Subarusted" got few problems starting when cold. But not always... ARGH Anyway I was suspecting either the following:
- Engine coolant temp going to ECU or wires between them
- Idle air solenoid sticking
- Accelerator position sensor, more specifically the idle switch

Sometimes it starts like brand new, even with temp around -15degC (10degF). Sometimes I struggle starting it cold in my garage (10degC/50degF).
No problem starting it when it's hot.

I also get some power surges, noticeable when driving at low speed. I would press on the brakes lightly, then the motor would kick or surge by itself. Sometimes it happens when the car is not moving. The motor revs to about 1300 RPM, and slows down to 1000 RPM. Pumping the accelerator doesn't fix it: the revs lowers down SLOWLY. It may take 3-4 seconds to go from 1300 to 1000 RPM!

When I'm able to start it, after few minutes, I hear a relay clicking behind the dashboard, on the driver side.

Now I will try checking the grounding with my multimeter. Battery was replaced in September. Maybe they wrecked my grounding strap


BTW, I had a timing belt pulley that gave up before changing the battery. The two bearings disintegrated. The pulley was damaged a little bit, but I was able to keep the pulley filing the rough edges and replace the bearings. I couldn't find any Subaru 93 in the scrap yards around here

Harlock

[TrendSetterX]

Sometimes it starts like brand new, even with temp around -15degC (10degF). Sometimes I struggle starting it cold in my garage (10degC/50degF).
No problem starting it when it's hot.

I also get some power surges, noticeable when driving at low speed. I would press on the brakes lightly, then the motor would kick or surge by itself. Sometimes it happens when the car is not moving. The motor revs to about 1300 RPM, and slows down to 1000 RPM. Pumping the accelerator doesn't fix it: the revs lowers down SLOWLY. It may take 3-4 seconds to go from 1300 to 1000 RPM!

When I'm able to start it, after few minutes, I hear a relay clicking behind the dashboard, on the driver side.

I have the same issues and the same relay-clicking noises which sometimes coincide with the check-engine light appearing/disappearing and the head-lights dimming. I also seem have a permanent ground-fault-loop such that listening to the radio is almost impossible (double-checked all radio grounds and everything is fine there).

Harlock, did you ever remedy or at least discover the cause of the relay clicking/etc?

Does anyone think this mod would help me out?

(Also note that my car has the rough-idle issues which I've yet to fix. The only thing I tried which seemed to help only a tiny bit was SeaFoam.)

Thanks,
Jeremy

91 n/a 5-speed

[kidwired]

ahhh so this is the DIY $15 ground mod.

Yeah, mmmmk this makes sense. A friend whos a radio nerd explained to me electricity resonates at different frequencies (apparently a bad thing in engines)....then I kinda got lost. He said unfortuantley auto manufacturers use the body as ground.....I got that part.
then he says the best grounds terminate all together. He pointed out the way BMWs ground, crazy looking mess of brown wires (components have own grounds for the most part) all going to just a few grounding points.

[gnuman]

I think by now this thread really deserves a sticky. Many, many people will be needing this info.

[IronMonkeyL255]

Heck, I may finally get around to doing this over the summer.......

[tris91ricer]

I did, and it's worth it. I'm even in the process of explaining how to do this to another LCO member, via PM. I'll have to track down a digicam, and take photos. I'd gladly rip my kit out just to show how it's done.. anyone near me wanna spend some time?

[IronMonkeyL255]

Did anyone figure out what size ring terminal could be used for the knock sensor?

Also, where have you guys been getting your wire and connectors?

[tris91ricer]

B&B auto, not more than $2/pc, upto 32" 4g cable.

[LondonThing]

First post here, please be gentle...

Reading all four pages, and having experimented a little with my 90 Legacy Turbo Estate over the weekend, I suspect the common factor here is ... salt.

Most of the people reporting improvements seem to be in colder climates: my estate is a Japanese car imported to the UK, which means it has moved from a country where they don't salt the roads in winter, to one where they go nuts with the salt. The difference in under-bonnet condition between a fresh import (even a ten year old vehicle) and one which has "been around" in the UK for a while is quite shocking - aluminium fur corrosion everywhere. UK Legacies also corrode the ends of the roof rails like crazy, due to a combination of salt in moisture off cold roads, and the "preferential electrode" effect. I've seen manifestations of this on several cars, including my old Mercedes estate which magically ran better after I took all the fuses out the fusebox and replaced them with new ones.

Aaaaanyway: the Legacy runs pretty well but thumps from 1st to 2nd gear when the transmission is cold. I put this down to tired brake bands and resolved to stick a transmission rebuild on the to-do list for early next year - but then, this weekend, the poor old original japanese battery decided it had done enough.

In putting in a new battery, I followed the earth lead forward to the front crossmember. The earth point there had the usual salty corrosion, so I scrubbed it down and covered it with copper grease when re-assembling. Started up and hey- no thumpy change from 1st to 2nd! My suspicion is that earth paths which, when cold, have gaps in filled with furry corrosion are all tight and firm when the transmission is warm.

So my view of the grounding mod is, you can probably get just as good a result from cleaning up the grounds you've already got (with the possible exception of the O2 sensor on the Zorst), and that being anally retentive about the cleanup process is where most of the benefit comes from.

[Bheinen74]

Simply go in an electric / electronic shop , and buy a 15-20" of 10gauge wires (would cost like 5$), and buy connectors for 10gauge. any clerk there can help you. it's pretty easy to do. you might need a "criper" too.

uh, you mean 15-20' not inches .....had to be picky.

[Manarius]

Well, I did the mod. I don't really notice any major improvements. Maybe because I did it wrong, or didn't ground the right places. If anyone would be willing to look over these pictures:

http://photobucket.com/albums/a339/Plan ... ing%20Mod/

I'd really appreciate it.

As a note: I tried hooking the wire to the negative terminal....I guess I need some sort of a adapter 'cause the bolt isn't long enough to hold those two cable ends there.

[Legacy777]

the strut and intake points look ok, but the one at the battery doesn't. You have it mounted to the hold down. Even if you have a line coming from the chassis, I still wouldn't recommend doing that. You should tie them together at the negative terminal of the battery.