Ground strap = MPG?

[Schelter]

I came across a site yesterday extolling the virtues of running a daisy chain of ground straps (battery to chassis, chassis to trans, trans to head, head to intake, intake to battery) to improve hp and mpg. A little Google searching found a couple dyno tests that saw minor (3-8)hp gains and some 1-2 mpg gains. They sell a kit for $100+ but found a few people making there own set for around $35. The unofficial "Butt-o-meter" tests say improved low end torque, smoother high end power and better idle. Any science behind this? I know a bad ground strap can cause all sorts of funny things but can a really good ground system help that much? Color me skeptical but for $35 and an hour or two...

[bhazard]

Go to your hardware store and get a nice piece of like 8 awg for $10 or so and some ring terminals for maybe $5 and go to town. Kits are a waste of money for the lazy.

You can always use an ohm meter to check the resistance between your - battery terminal and various parts of the car, and compare before-after your new grounds.

New grounds may not help if youre already well grounded but I dont think they can ever hurt.

[mwebb]

OHM Meters are right next to useless when working on cars
the ECM does NOT see resistance .
the ECM Does see voltage and in a loaded / working circuit Voltage drop is one of the primary causes of broken cars , you will NEVER find a voltage drop with an OHM meter.

OHM meters can not load circuits and can not test loaded circuits.

ground circuits should all be the same as battery negative
so
negative test lead on battery negative , positive test lead on suspected ground , engine at idle with heater blower maxed and High beams on

voltage on the ground circuit with respect to battery negative can not be above
50 millivolts or .050 volts for "smart" computer related circuits
or 200mv or .2 volts for "dumb" circuits that are not computer related

lower is better .

0 volts is the optimum and sought after voltage drop value .
in a LOADED circuit
with respect to battery negative , when testing grounds

and when testing supply , the same values apply , with respect to battery positive OR alternator positive which should be 0 volts different from each other in a loaded circuit in a perfect world .

you can make redundant grounds or repair damaged corroded connections as needed to get voltage drop values within spec
no "kit" required .

[TheEnemy]

On a car with sensors everywhere, a grounding issue can throw off what the sensor is reading, though from what I have seen many sensors have their own ground wires now.

Even a good multimeter will measure resistance with an accuracy of +-0.1 ohms. But if you have 10A running through that part of the circuit that could be a difference of 1v!

[Krayzie]

it will help especially with older cars whose grounds aren't as good as they used to be due to time. Plus bigger will provide less resistance than what you have at stock. i've done it and it has lowered my idle and made the shifts a bit smoother.

some info for you http://www.8thcivic.com/forums/i-c-e...big-three.html


heres mine

link to album http://s60.photobucket.com/albums/h1...ounding%20Kit/

[SVOboy]

Yeah, grounds are definitely a key issue, but I wouldn't waste too much money on them. Personally, they gave me hell trying to get them right when swapping in the insight engine, but I wouldn't lose sleep over them either

[Ryland]

In theory you should see the same kind of improvement if you clean up the ground wires that are already there.
VW's are known for having bad ground connections and having them cause all kinds of problems, apparently Saturns also have an issue with a bad ground that causes the check engine light to come on for a sensor that the car does not have.

[mwebb]

..."But if you have 10A running through that part of the circuit that could be a difference of 1v!"...


some cars like Geo Metros , run many of their grounds through a common ground at the rear of the intake .
a 1 volt drop to battery negative on that ground would cause radical problems in a Geo metro

for instance
the 02 sensor signal that should be 150 to 850 mv would now be
1150 mv to 1850 mv and the ECM would Code for 02 sensor circuit ...

joe dumb driver
would replace the 02 sensor for about $200.oo and
the problem would remain UN changed,
so joe would take the new very fine 02 sensor back to auto junk and scream about the low quality and poor engineering and
get another one under warranty .

which would fix nothing . imagine joe's frustration , imagine the auto junk employee's frustration ....

replay that scenario for all the rest of the sensors
(which is all of them on a geo metro)
on that ground circuit and
you get a idea of how significant bad grounds can be

even worse if it's only a 100mv drop as now
there are no DTCs
but the car runs like a bag of a$$holes and gets 22 mpg .

[bgd73]

factory grounds work, if they do not, you may have tight channels that need to be broke open, stronger welds in places...clean clean clean.

and i found aluminum in the back, with a whiff of air is doing all those straps are doing, all at once.
The trick has been known forever to stubborn cars, today it is called a diffuser and found on ricers most often, with turbo engines.. Down low, in the rear..sometimes looks like a radiator.

I chose a solid sheet of thin aluminum, riveted..in front of rear bumper..nothing to see, it is hidden..blow off the blue crsytals of interaction chemistry once and awhile. Quite noticable on my old subaru. Alot of iron in the old buggy...

[comptiger5000]

Between yesterday and today, I've added a few additional grounds to my Jeep with some extra wire and terminals I had laying around. I've only put about 10 miles on it since, so I don't know if it will help MPG, but it does tell me my stock grounds need some cleaning. The volt gauge definitely drops a bit less under heavy electrical load at idle. It seems to have a hair more pep off the line too.

I grounded with a 12 gauge wire direct to the battery negative from the dipstick tube mount (on lower alternator mount, and close to ignition coil). I tied a 14 gauge wire from where the voltage regulator mounts to the top of the alternator into the 12 gauge ground. I also added a 12 gauge ground from the battery negative to the screw where my aux driving lights ground to the body. I added another 12 gauge ground from where one of the fuel rails mounts at the upper rear of the intake manifold to the top of the firewall, where the stock engine ground straps run to.

I'll keep an eye on it and see how she does. I figure I might see a little FE improvement, as I think I'm getting stronger spark now. I doubt it will be much, however (probably between 0.1 and 0.3 mpg).