"Hot" ground question for the eletronic guys

[Farabomb]

Work was real slow today so I was crusing the NASIOC forums (http://forums.nasioc.com/forums/index.php?s=) today and came across this. Scooby mods (http://www.scoobymods.com/forums/showthread.php?threadid=1197)

I knew I has some 10g amp wire in the garage so I figured what the hell. I picked up some crimp-on connectors on the way home and busted out the dremel for it's first non-RC car/computer related project. After about 25min total including finding my tools in the dark :darkroom: because getting the flashlight out of the car would've been too easy. ;) I have it 90% done. Looking back on the threads I need some more wire to make a few key connections (ie: the block and the coil pack) Seeing as I've seen people say it made the car run better to it didn't do sh*t I figure the $5 on crimp ends and less clutter in the garage is a win-win situation for me.

Now here's the thing for all you electronic guys. Don't think in the realm of cars, think about electronics. The car's computer is nothing more than a microprocessor that takes readings from sensors. It can be either digital or analog and most times bolth. WHY would this work? I know from working on cars that intermitent grounds can cause all sorts of strange problems. You used to be able to fix a car with a pair of vice-grips and a hammer or a larger hammer. Now with all the computer controled cars out there the electrical system is much more important. With my limited knowledge of electronics I can understand how a CPU can tell differences in milli-volts. Can a difference in the ground reading cause the readings to be skewed/fail in a car computer? I would figure there is a +/- variable built into the programing but can it handle all the variance of multipule sensors failing/reading wrong?

In the end it doesn't matter to me but I'm real curious about what you think. I'm picking up the extra parts I need tommrow on my way to see how much labor is going to cost on a AWD clutch replacement. I'll do a RWD clutch in a driveway if needed but a lift and not having to deal with the extra 2 driveshafts is well worth my money. :D

[Synthohol]

A good solid ground is important for reference, i mean like say an outlet in the house is 110v, well what makes it 110? if ground or neutral has 5v running through it only 105v is being delivered.

on the copiers and printers i work on all day, all the paper path sensors work off a 5v circuit. 5v is being delivered to one wire in the 3 wire sensor at all idle times, one is earth ground from the wall outlet and when the sensor is blocked as a paper goes through, the third wire sends the 5v signal back to the logic circuit on the mainboard. if the ground circuit has just say 1.5v neutral to ground, only 3.5v is sent to the mainboard and the logic circuit is looking for 5v, so the copier usually jams for no apparent reason, no wrinkled paper, it just triggers a missfeed due to an improper signal being sent to the mainboard which relies on the timing and duratiion of the feedback voltage.
on cars i would have to say resistance is not futile, its mandatory for reliable feedback voltage reference:)
I hope that helped!

[Player0]

Grounding in cars is a very odd situation. Car manufacturers save a lot of money and space by NOT using ground wires.

Grounds are usually supplied by the Earth itself (Earth Ground). The Earth of course has charge, and the grounds in your house are supplied by metal pipes or rods embedded in the earth, which contains salts and other conductive materials. Earth ground is almost never exactly 0 volts.

The car is mostly insulated by the earth by rubber tires. A wonderful thing in fact, since I've been in a car that was struck by lightning, and if the car had a better Earth Ground, I'd probably be dead.

Most cars have a Negative Ground, (0 volts) however...some cars have a Postive Ground, mostly older ones that I am aware off. You can have a Postive Ground (making the metal of the car positively charged) because the car IS isolated from Earth Ground.

In a car, the battery supplies the energy potential, and the battery is mostly responsible for Ground. However, static electricity does build up on a car. This will swing the voltage of the car up or down a little (usually up). Of course, the car is also a big antenna, and EMI and even things like a television broadcast will change the ground voltage a little. It's a lot easier to make the voltage of the metal of a car fluctuate than it is to change the voltage of the earth (which is usually left to the Wind and friction) so the Ground of a car is certainly less stable and reliable.

The wiring kit? Well, it works by reducing resistance really. Modern cars especially have much less metal in them. That means that running the negative terminal of the battery and then pickign that up at the ECU or something may have a slight resistance, and you will get a slight voltage drop. And yeah, some sensors might be affected. However, the ECU will recalibrate on the sensors every so often, so thats really not a big issue.

So the wiring kit may increase voltage and decrease resistance. However, you are certainly NOT isolating the electrical system from the car's ground. Take my speaker installation, the speakers could be hooked to ground as well, but by running seperate grounds, you help isolate them, you reduce EMI and reduce noise. Yeah, EMI can do a lot more to screw up sensors than voltage differences, since you can recalibrate for those. EMI is very random.

Hey, for $5, it's worth a shot. I don't think it could improve performance myself. Its one of those little things you cant really prove. Maybe on a Dyno. You might actually pick up more EMI with all those thin wires around. It should definitely help the alternator-battery charging system though. In fact, I changed those wires out myself on the Honda. Id replace the battery negative terminials with good ones and run 4 guage to the frame and 4-8guage to the alternator with good oxy-free wire.

[Farabomb]

Well, my patented assdyno isn't registering anything. :D

I'm off to go and pick up the rest of the parts. :)

[Farabomb]

I have more results from the assdyno. :D

When I first did the mod and reset the ECU I didn't notice anything. It was still running a bit rough and the off idle throttle response still sucked. It would allways stumble if I reved it with no load and every once and a while it would bog under load. I blame my heavy foot and a cold engine on most of the boging issues. There was also a hesiatiation inbetween 3.6k-4.2k on the tach under load. It was barley noticible but it was there.

I only connected the - from the battery to the strut tower and tied the 2 towers together last night before I ran out of cable. I cleaned all the paint off on all the connection points including the stock mount so I had a bare metal connection. On my quest for 10g amp wire (seems at the 6 places inc. a car audio installer dont get spools of wire anymore. All I found was blister packed amp kits with one Rockford one costing $150 :eek: All I wanted was 2ft of damn cable :) ) and my trip to work I noticed a difference in all around throttle response and smoother running. I don't know if it's in my head but it really seems to run smoother and there is no lag anywhere in the RPM range.

I met up with Synth on the GSP and after a little driveway enginerining I finished the connections up and it's now done. How sure am I about the difference? pretty sure. Like most things you overclock it's hard to tell without a benchmark. My benchmark is driving the thing dalily and it's only one day. I can honestly say I can tell a difference but I have to beat on it a little more before I can truly tell a difference.

In further reading I noticed some people getting better results after a while. Maybe it's the ECU learning with a better reference? I don't know. I also see a few people having CEL's (check engine light) come up later but scoobys seem to like doing that for some reason.

After replacing a LOT of sensors in order to fix my random no-start problem, hopefully it's gone now. ;) I start thinking maybe the gound might have something to do with it. I got the car with very little miles on it (under10k I think). It's now 71k hard miles later things are failing. I beat on the car, I beat on anything with a motor. I drive fast and hard, must have something to do first 3 cars being comaro/firebirds and riding motorcycles/ATCs since I was old enough to pull a clutch in.:) I ask alot of my cars. I hurt this one a while ago and I have to fix it soon.

I'm wondering if the problem is limited to Subarus or maybe all makes of cars. Weird things happen under the hood. I've seen parts go bad for no apprent reason. Maybe someone else with a late-model car (OBD-2) could do this mod and see what they come up with. All it costs is some time, wire, and crimp-on connectors. Kits are nice but too much $$. I think in cars with systems would really benifit from a good ground. If this works long-term I will be re-doing it with good cable and some silver solder.

Enough of my rambling. I'll post the long term results after some seat time.

[tripodal]

Well after working on cars for 5 years now, I can tell you, there are never enough grounds. The best example anywhere is on 90-97 hondas / acuras. There is one 10-12 gauge wire going from near the radiator to the valve cover.
I dare you to disconnect it and try to start your car... It wont.

P0 is exactly right saying its cheaper to put in less grounds. They put in the mininum to make the engin run good for the warranty period.
These ground wires dont usually fail, but wear down.. the moter is not stationary and the movment is constant, wearing the wires down quite a bit.

IMO the best additional grounds will be adding them between the engine and frame, between the alternator and frame, and between the alternator and the battery.

The stories of great and noticable increases in torque etc, are most likely releated to a failing coil. As they age they will require more current, and thier available voltage will drop as a result, extra grounding will help keep that voltage towards the 14+ volts the alternator shoudl be genearating, vs. a batterys 12.6v resulting in a much stronger spark.
My alternator is currently in its last days, the light has been on for about 2 weeks now... im too damn lazy to replace it. So i just have a voltmeter in my car, so i can monitor it. Interestingly you can see a .5volt swing just by acclerating. I didnt really imagin that the denser mixture woudl really work the coil that much more. But it does. (the car is carbureated)

I reccomend anyone out there to do this grounding as it can only be good as long as you have some common sense.

ALSO if you do replace your clutch, find a place ot have the flywheel lightened and balanced. TRUSE ME you will love the difference .2 seconds of 0-60 easy (if theres anythign to take off)
plus the vibrations will decrease from your motor (tho it may runa bit rough. ) Also your clutch will last a bit longer when driving hard (speedshifting) as the engine will more quickly mate.
If you take that clutch out with out having the flywheel done I will smack the heck out of you!!!!!!!! im having it done on my 86civic this winter... for about $125. Its well worth it.

[Player0]

Thanks trip, now i want to try it! wheres my blowtorch?

[krucibus]

The ground sytem on a car is simple: It's merely a return path for the voltage flow from the battery or the alternator. In other words, when you start the car, it closes a circuit in the starter solenoid, which energizes the starter. When you turn on the lights, it closes another circuit. When the points or the electronic ignition or fuel injection or whatever come in phase for their respective cylinder, it closes another circuit. And so forth. It doesn't matter how much voltage you are dealing with, weather it's 2.5 volts for a dashboard light or 10,000 volts for a spark plug, when the respective circuit closes, the ground provides the "escape" route for this voltage push.

Measurement sensors work off differentials, weather it's a voltage range for an Oxygen sensor which is sampled several times a second, or a resistance range such as in oil pressure and fuel gages or in the interior lights brightness switch if it's rheostatic.

Indicator sensors will light up is there is voltage present when there shouldn't be or vice versa, such as in "check engine" lights.

Finally, there's the solid-state sensors, used on modern cars with on-board engine management chips. We all know how those work.

So when you're thinking cars, if you're used to thinking as an IBM technician, this is fine for a cars' electronics, but most other electrical systems are extremely simple. I don't know how many times someone has brought me their late-model Honda or Ford so I could fix something they thought was electronic when all they had was a faulty connection or a burnt-out sensor. I love fixing things and showing people what the problem was, hopefully I've encouraged some of them to tackle the job themselves and enjoy the same feeling. Isn't entropy great?:)

[Player0]

Well Farabomb came up this weekend to hang out, and we did the ground mod on my Honda. It was a real simple and quick job. We used 10g wire and he had some ring terminals. It took what, an hour tops Alex? Anyway he did most of the work, and we also rewired the battery terminals which I hadn't done right when I installed the car stereo. A sanding sponge and some dielectric grease helped make the connections.

Does it work? Well, it does do something. My car idles higher now by a few hundred RPMs. The throttle is much more consistant, as where before it would kinda waver by 100rpms at a time, now it stays pretty steady, just up higher.

The voltage I measure at the rear of the car has increased by about .3v. This is most likely due to the better grounding in the front. This is giving the amp about 12.1v with the car not running, where it wasnt quite 12v before. Yeah, my battery is probably getting weak and should be replaced.

Do I feel more power, or like I'm getting better gas mileage? Nah, I doubt it. I'm sure the improved grounding has simply risin the voltage off the battery, and is doing something odd. IM sure the sensors will all 're-learn' their peak settings givin these new base voltages so...I dont expect more power. But, probably a little more consistant, and a little less rough.

Now if I could just fix the muffler.

[spldart]

Originally posted by krucibus
The ground sytem on a car is simple: It's merely a return path for the voltage flow from the battery or the alternator. In other words, when you start the car, it closes a circuit in the starter solenoid, which energizes the starter. When you turn on the lights, it closes another circuit. When the points or the electronic ignition or fuel injection or whatever come in phase for their respective cylinder, it closes another circuit. And so forth. It doesn't matter how much voltage you are dealing with, weather it's 2.5 volts for a dashboard light or 10,000 volts for a spark plug, when the respective circuit closes, the ground provides the "escape" route for this voltage push.

Measurement sensors work off differentials, weather it's a voltage range for an Oxygen sensor which is sampled several times a second, or a resistance range such as in oil pressure and fuel gages or in the interior lights brightness switch if it's rheostatic.

Indicator sensors will light up is there is voltage present when there shouldn't be or vice versa, such as in "check engine" lights.

Finally, there's the solid-state sensors, used on modern cars with on-board engine management chips. We all know how those work.

So when you're thinking cars, if you're used to thinking as an IBM technician, this is fine for a cars' electronics, but most other electrical systems are extremely simple. I don't know how many times someone has brought me their late-model Honda or Ford so I could fix something they thought was electronic when all they had was a faulty connection or a burnt-out sensor. I love fixing things and showing people what the problem was, hopefully I've encouraged some of them to tackle the job themselves and enjoy the same feeling. Isn't entropy great?:)

This is somebody with a good grasp on electron flow and electronics.

[tripodal]

Originally posted by krucibus
The ground sytem on a car is simple: It's merely a return path for the voltage flow from the battery or the alternator.



A firm grasp indeed, but alas, i cannot let you get away with it.
LOL Technically electricty flows from negative to positive. IE from ground through the wire to the positive terminal of the battery & alternator. Its just easier to think about it in reverse.

[Player0]

Bah, don't make me whip out the quantum physics ;) Electrons 'flowing' in any direction is just a really good analogy to something we don't really quite understand in the first place ;) There's a lot of theories out there about how the electrons aren't really flowing in DC anymore than they do in AC, however the EM force kind of rotates in the same direction. There's some magnetic principles involved and it's all quite interesting and quite confusing.

Electrons flow towards positive, and the 'holes' flow towards negative, so it all depends on what you're talking about what's flowing. I doubt that the electrons in a circuit are really moving too far at all.

[illmatik]

Damn all this car talk depresses me. I have to get rid of my car :(

:(

[Farabomb]

Originally posted by illmatik
Damn all this car talk depresses me. I have to get rid of my car :(

What kind of car?

Why are you getting rid of it?

[illmatik]

I have a measly old 90 Accord EX which I had plans of swapping in an H22A w/ jackson supercharger, but car expenses vs. the amount I use the car, insurance, and garage fee just dont warrant keeping it active. I'll be bringing it up to diddletown to sit in my 'rents driveway till I can justify the expenses. I'm hoping by the time I really need a ride, I'll be moved out to the burbs and the proud owner of a WRX wagon or even STi (or maybe an Audi S4 Avant if 2004 is as profitable as the market predictions)

[Farabomb]

I think you can tell where my car loyalites lie. ;)

I love my scooby. I'd really like a STi, even thou I'm not a fan of how they look (I think the older ones are much better looking), I allmost can't while living in Northern NJ. Seems that the car theifs have realized just how nice the STi' and WRXes are. They're stealing them left and right up by me. :(

They're big fans of the A4s and the S4s. Bastards... :mad:

[illmatik]

Yeah.. Well I live in queens so you can just guess what happens to em here. Yeah I really like the box headlight model RS's myself. If I were to drop the $$ on a sti, I'd have to get a custom job to remove that gay *** spoiler. Way too ricey for my liking, I think it spoils the look. Theres a guy on my block w/ a civic w/ that fin and one of those whoopy cushion exhausts. If we didnt have nasty winters here (or I get a house w/ 4 car garage) , I'd be all over some big block american muscle. Come to think of it, wherever I end up I'm still gonna be all over a 79-80 911 Turbo (930) like sausage on saurkraut if a rust free one crosses my path.