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Old 02-19-2002, 02:34 AM   #1
mynew02
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Default Negative Battery Grounding Issues - hesitation 3000 RPM

Rifts WRX (projectwrx.com) has a mod up concerning running ground wires to the body and motor to ensure a good ground.

I spoke with Mark at TurboXS and he though WRX's have problems with bad grounds, causing the hesitation through 3K RPM that everyone complains about. My WRX is aweful from 3-4000 RPM with the hesitations.

I have several questions about this:

1. has anyone had their hesitation problem totally fixed by this mod or has anyone tried this mod and not had it make any difference over time?

2. Are the ground points described in projectwrx.com do-it-yourself guide really the best places to ground to? Also he doesn't cover the points that he grounds to in great detail. What specifically are the best points?

3. Doesn't grounding to two spots on the body and or motor cause potential ground loops? I thought you were only supposed to ground to one location (one spot on the body and one spot on the motor)... so wouldn't replacing the factory 8 guage ground wires with 4 guage be a better solution?

Interestingly Dave_MacKinnon says:

"Somewhere just above 3000 RPM, there seems to be a hole in the fuel map, the engine goes way lean for about 1/2 second whole rolling the throttle on.. "

That's in this post:

http://i-club.com/forums/showthread....hreadid=148650

Thanks...

-Jonathan
______________________

P.S. Here are some threads that I think are related to my problem...

http://i-club.com/forums/showthread....hreadid=148650
http://i-club.com/forums/showthread....hreadid=142304
http://i-club.com/forums/showthread....hreadid=129823
http://i-club.com/forums/showthread....hreadid=133563 (last post only)
http://i-club.com/forums/showthread....hreadid=128057 (at least 3 people complain here of the problem I have.. not boost cut either like the first complaint. I know what that is...)
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Last edited by mynew02; 02-19-2002 at 02:54 AM.
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Old 02-19-2002, 02:52 AM   #2
nhluhr
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pending my ability to source some 4ga tomorrow, i'll be doing this mod tomorrow night after work. I'd really like to see some *optimal* locations and opinions posted before then!
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Old 02-19-2002, 02:59 AM   #3
mynew02
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BTW.. I added some things to my post above so check it out again.

A bit more info... I called Vishnu today, Shiv wasn't there. The other guy (can't remember his name..sorry) said that they have been hearing of the problem too but asked Subaru of America about the grounding idea and they said grounding at multiple points could cause ground loops. Funny thing too is that I went to circuit city this evening to get 4 guage wire and the guy says, "I wouldn't do that, that will cause a ground loop if you terminate at multiple points." It seems it's ok to terminate at one point on the body, motor and frame but not a multiple points on those parts of the car... get it?

I really want to get to the bottom of this so if someone can get some proof that the sensors are wacking out around 3-4K causing those slight hesitations it would keep me from going INSANE!!!

If you have any info at all please post here and keep checking my thread above as I may add to it...
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Old 02-19-2002, 03:20 AM   #4
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This whole grounding thing seems wierd to me because if it is EMI as is claimed, then how is changing the ground cable to a higher gauge going to help? I wrote something similar to this here.

Anybody got any ideas as to why this works (or doesn't )?
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Old 02-19-2002, 04:07 AM   #5
HM3SC
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I have been using the Pivot Earthing kit for 2 months now. No problems.

I was getting major engine hesitation from the unichip (verison1) around 4000rpm. Right after the Pivot kit, 99% of the hesitation was gone, engine seemed more responsive and the volt meter was 0.1 higher then normal.

The kit cost me 90usd. When i was at the shop installing it, there was a Ferrari dealer mechanic there too, he was was laughing his ass off, saying that i was wasting my time and money.
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Old 02-19-2002, 05:05 AM   #6
donrgolf
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Not sure how to post a thread, but if you do a search on "Single Point Ground" you will see what I did to solve the problem you are seeing. I provide a good write up and pics.
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Old 02-19-2002, 07:36 AM   #7
okamikatekore
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Default i found a similar mod on a jap website...

donrgolf.....this is very similar to yours but different ground points,any difference you think???

opinions vary on this mod.the guy at the audio shop where i got the cable from knew about it and said it worked,but mentioned not many know.i went to an auto electrician who had no idea what i was talking about told me i was wasting my time UNLESS, the factory grounding job wasnt very good,then it MAY help.
ive done RiftsWRX mod,using 8 guage(i know,wrong guage )and it does feel smoother between 2k-3k rpm.(my imagination???)anyway....i found the following mod which,from what i understand,grounds to five separate locations directly from the negative battery terminal using 6 or 8 guage.im already half way there so i will try this on the weekend and see if there is any difference between the 2 variations of the same basic principle.

this is how babelfish translates it:

The ground, the ground directly, the battery - the method the terminal of connecting.
Usually, the ground - has returned via the body and the like. Losing the wasteful resistance, the direct back
The terrier(earth.) - by the fact that you connect to the terminal, the power at the time of low-speed torque rise , fuel economy improvement and air conditioner use
There is an advantage such as E prevention and life improvement of the battery. It seems * & *.

Ground method
It prepared the thing
* Graounding cables 6 for 8 gauge audio m
* Crimp contact
* The crimp contact is locked the tool


Ground place
1. Alternator - vicinity
2. Engine left intake manifold
3. Engine right intake manifold
4. The left striker(translates as striker,i think strut tower )
5. The right striker

Because the tool which locks the crimp contact does XXYEN about 5 and 000, you borrowed from the friend.
You suffered hardship a little to obtaining the graounding cable for audio of 8 gauges.

Effect: It is thought low-speed torque raised. Also powering down at the time of air conditioner use was gone. To fuel economy
Being attached, the resonator - it meaning that the effect is large, you cannot say at all
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Old 02-19-2002, 07:52 AM   #8
chuglobal
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Default Yo

To make it short, so does it work yes or no? What gauge will I need, 4 or 8? Too much debating ... just the answer please .
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Old 02-19-2002, 07:55 AM   #9
okamikatekore
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Default depends on which one you do

do RiftsWRX,use 4 guage
do the single point ground,use 8 guage
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Old 02-19-2002, 08:07 AM   #10
donrgolf
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Ground place
1. Alternator - vicinity
2. Engine left intake manifold
3. Engine right intake manifold
4. The left striker(translates as striker,i think strut tower )
5. The right striker

These are all good ground points. I use all of them with the exception of the alternator vicinity. I'm thinking the passenger side intake was close enough to the alternator. Putting a wire on the alternator would not hurt. The more single point grounds the better. You have to find the right compromise between every single electrical device having its own ground wire run back to the battery and what the factory puts on the car. A point not on this list I would deem essential is the short wire close to the battery that connects to the body. I added a wire there to beef it up. I used 8AWG wire which was a compromise to the #4 wire I seen others do.
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Old 02-19-2002, 08:24 AM   #11
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Default Re: Yo

Quote:
Originally posted by chuglobal
To make it short, so does it work yes or no? What gauge will I need, 4 or 8? Too much debating ... just the answer please .
It worked on my car.

4 or 8 ? More important than what gauge is how many points you pick up. The more the better. That said I would not go smaller than 8awg on the wire. I used 8 because it is easier to work with.

Orginal writeup - http://www.i-club.com/forums/showthr...78#post1516578

Last edited by donrgolf; 02-19-2002 at 08:57 AM.
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Old 02-19-2002, 11:17 AM   #12
mynew02
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Default

Guys.. I'm looking for more detailed answers to the "whys."

I would like to know what sensor is having trouble.. is the MAF?
Where does the wire to the MAF terminate?
Should we put a ground strap there?
What other sensors may be having trouble?
Do most sensors negative wire go back to the fuse block?
Should we get a real good ground on the fuse block?

more data!!!
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Old 02-19-2002, 11:28 AM   #13
chuglobal
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Default Humm ...

So I should go w/ 8 gauge sire if I decided to do this mod? Use it between the battery and sturt tower and engine.
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Old 02-19-2002, 11:28 AM   #14
RiftsWRX
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I have to make one comment about ground loops...


I can name at LEAST 3 points right now.... and there are a lot more...

1:Battery negative right to the frame...
2: STARTER ground to the rear firewall
3: the entire ECU is technically a ground to the floorboard

Go figure....

If having multiple ground points causes loops... they got it wrong from the factory to begin with

Jorge (RiftsWRX)
www.ProjectWRX.com
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Old 02-19-2002, 12:03 PM   #15
mynew02
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Jorge,

Thanks for you reply...

There are only two actual points that connect to the negative on the battery. These are the body right behind the battery and the back of the motor under the interooler.

That means that any ground signal traveling to the battery will have to travel across one of those two wires to return to the negative post of the battery. I think they feel that the body is isolated from the motor and treat these as two seperate bodies (I.E. rubber motor mounts separating them electrically.)

Now I could be wrong on this but I though that a ground loop was when the ground signal could travel across two paths back to the battery with varying resistance (I'm certainly no expert on this and this could be totally wrong, I just though this was the theory.)

Now if something works screw the theory, but maybe if we approach this more scientifically and both test sensors to see how the electrical load fluctuates (if at all) and also follow good practice in grounding we may come out doing the job Subaru should have done from the start...

I'm waiting in anticipation of the wideband 02 readings that will tell us that this hesitation is being caused by bad grounds and then we can go about fixing it...

I would think that grounding points near the sensors negative wire termination would be the best point. Again does anyone know if the negative wires for the sensors all ground to one location? If so where?
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Old 02-19-2002, 12:24 PM   #16
mynew02
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Wow.. how did I miss this one?

http://www.i-club.com/forums/showthr...hreadid=141932

Thanks donrgolf

-Jonathan
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Old 02-19-2002, 12:24 PM   #17
RiftsWRX
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Quote:
Originally posted by mynew02
Jorge,

Thanks for you reply...

There are only two actual points that connect to the negative on the battery. These are the body right behind the battery and the back of the motor under the interooler.

That means that any ground signal traveling to the battery will have to travel across one of those two wires to return to the negative post of the battery. I think they feel that the body is isolated from the motor and treat these as two seperate bodies (I.E. rubber motor mounts separating them electrically.)
Interestingly though... consider this...

So the ground stops at the motor mounts... but continues through the trans, through the driveshaft, and half shafts to the CV joints, to the hubs, control arms, brakes, struts, springs, strut towers, and back to the battery. Then on the back side, driveshaft, differential, to the frame anyways

hehehe see what I mean? where does it end It's all about resistance, at that point, back to the battery.

Jorge (RiftsWRX)
www.ProjectWRX.com
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Old 02-19-2002, 12:46 PM   #18
mynew02
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I'm not disagreeing.. just trying to understand.

So I guess the key is for all the sensors and electronic parts to have the same (resistance, impedence, whatever) back to the battery to provide level readings to the computer.

Should we connect a ground strap somewhere on the exhaust for the 02 sensors?

I'm gonna trace the negative wires on the sensors to find where they terminate and put a ground wire there and also gonna do somthing similar to your mod...

I saw a cool battery post at Circuit City that had (4) 8guage outputs. I wish I could find one with (8) 8guage outputs or (4) 4guage outputs right off the battery.. that would be nice.

-Jonathan
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Old 02-19-2002, 01:04 PM   #19
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The more "ground points," the better.

From an electrical standpoint, you want as many low-resistance connections to ground as possible. The "best" grounding situation you could ever have in your vehicle is for every electrical component to be simultaneously grounded through large-gauge (low AWG) to both the battery directly (via a long wire) and the body/frame (through the shortest possible wire). That will minimize ground loops, minimize EMI, and give you the best reference possible.

I'm going to be going through and grounding a bunch of my engine parts much like Jorge, but not for sensors -- my radios get a lot of interference in lower frequencies (around 30MHz), especially from things like the fuel pump and injector system.

/Andrew
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Old 02-19-2002, 01:35 PM   #20
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Can someone explain exactly what a ground loop is and why it is bad?
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Old 02-21-2002, 11:05 PM   #21
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Quote:
Originally posted by Wreckleford
Can someone explain exactly what a ground loop is and why it is bad?
i know when installing a car stereo you're supposed to avoid ground loops because the different paths back to the battery have different resistance and different lengths so it might cause some distortion in the audio... but as far as making an O2 sensor work reliably? does a ground loop make a bit of difference!?
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Old 02-21-2002, 11:53 PM   #22
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One thing you guys may consider...

The grounding mod may not really help by getting a better ground to the system, but it may help because it strengthens the ground on the drivers side of the manifold which is the ground for the injector harness...

I had this ground loose and it gave me fits... rough idle, jerky acceleration... fixed it, and never had another issue.

-Nathan
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Old 02-22-2002, 12:35 AM   #23
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OK - I have actually done this mod and it seems to work, so here is my THEORY of why the Earthing Ground mod works.

Basically, a ground loop causes different sensors/devices to see different potentials. If the earth ground is 0V at the battery, a ground loop could cause a sensor to see it's ground to be 0.01V and the ECU could see it's ground as being 0.15V. Therefore a 0.9V signal coming from the sensor would be seen as a 0.9V - (0.15V@ECU - 0.01V@Sensor) or a 0.9V - 0.14V = 0.76V reading. So instead of the ECU seing a sensor output of 0.9V, it see's the sensors output as 0.76V, causing it to make the wrong adjustments. Also this Earth voltage (potential) the sensor and the ECU see's is also changing with time due to the amount of current each is pulling. The addition of multiple 4AWG wire decreases the amount of resistance in all path's back to the battery ground. Because of this the ground of all of the sensors and the ECU (and everything else for that matter) are going to be much closer to the battery's 0V ground reference (earth potential). So the delta for each ground will be smaller causing the ECU to see the sensor's output voltage as being much closer to the value it actually sent.
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Old 02-22-2002, 01:17 AM   #24
mynew02
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I connected a 4 guage ground to the driver side of the motor and it did improve things, but they still are not perfect. Look out though, I may connect a ground wire to every piece of metal on my car! No...seriously I think I will run at least 4 more out to different locations around the engine compartment.

This should be sticky because TONS of people have complained about jerky performance.
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Old 02-22-2002, 08:01 PM   #25
PAWRX
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Well, I have to admit I wasn't sure if this mod was going to do anything. But for the price I figured why not. I am impressed! My accelleration is much smoother! The battery terminal is a little cluttered, but not too bad. I didn't feel like spending the money on a distribution block.
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