calling all renix gurus and others...

[5-90]

Oddly enough, yes it does. Although I probably should have specified "separate conductor elements" as not being individual strands of wiring, but more like where a terminal is crimped on or somesuch.

If this is so, tho, why does a ground strap soaked in crud conduct less well than a clean one? Or would it be concident with contamination of the crimped connection (oil wicking into the crimp join between the strands by way of capillary effect, or somesuch?)

Just trying to get a full grip on the matter for future reference.

 

[Ecomike]

I would say this is the correct annalysis:

"Or would it be concident with contamination of the crimped connection (oil wicking into the crimp join between the strands by way of capillary effect"

Especially if there are traces of H2SO4 or H2CO3 (sulfuric acid, or carbonic acid) in the oil. Condensation overnight plays a big part too.

Try taking two duplicate, brand new cables, remove the insulation from the middle of one of the brand new cables, leaving a good 6 to 12 inches of insulation on the ends, then dip the exposed middle wires in water (use a plastic bucket!! so as not to creat an additional ground), or oil and measure the conductivity across the wire and compare to the fully insulated wire. You could even run a load test that heats the wires up to compare loaded conductivity.

Be sure to test the two wires first (before removing insulation) to make sure the two insulated wires have the same conductivity, or do the load tests first on them. The load tests would be a more precise test.

Take say a pair of very closely matched 100 ohm high power resistors on one end of each wire, then power the wire up across a 12 volt battery. Even better, maybe use a 12 V head light bulb. Use the same bulb and battery to test both wires, or load test to find two matching bulbs.

All other things being equal, (equal battery voltage, equal light bulbs or resistors) I doubt you could measure any difference in the two wire sets conductivity or back voltage due to the oil or water contamination of the middle wire bundle.

But that same contamination if it wicks (capillary action) its way to the end connectors can cause corrosion at the wire to connector contact
points in just a few weeks especially if it is corrosive oil like battery acid fumes and that will cause loss of conductivity, or old overused oil.

For others reading this that don't know, resistance is inversely proportional to conductivity.

R = 1/C

C= 1/R

I would find it interesting someday to see if a wide flat thin strap carries more current than one with the same wire size and wire count as a round cable bundle, due to spreading out the surfaces of the wires. In other words, at some point the geometry of the cable affects the surface area relationship of the multiple wires to each other.

 

[m0n3ym1k3y]

um i get the ground thing but damn how does the rest help? come on guys. any ways cleaned out the iac checked for vac leaks again found none checked tightness of stuff....and everything was tight guess ill add some grounds . oh yea it only does the stumble lack of power thing under load like takin off from a stop light and it eats gas. but it goes away if i wind it way out sometimes.

 

[Ecomike]

That sounds like a classic O2 sensor dying. Poor mpg, runs great at WOT (O2 sensor is bypassed at WOT), at 1/4 to 1/2 throttle the O2 sensor responds too slowly to keep up so it stumbles!!!!!

It might contribute to a high idle, hard to say. Also, nd exhaust leak can leak backwards between exhaust pulses (venturi effect), drawing in air and excess O2 that fools the O2 sensor into running the engine or some cylinders too rich. I just found cracked welds on the manifold pipe connections on one I am doing a head job on. Seems cracked 4.0 exhaust manifolds are common.

The O2 sensor can be tested with an analog volt meter. Search for "oxygen sensor test Ecomike" for details.

um i get the ground thing but damn how does the rest help? come on guys. any ways cleaned out the iac checked for vac leaks again found none checked tightness of stuff....and everything was tight guess ill add some grounds . oh yea it only does the stumble lack of power thing under load like takin off from a stop light and it eats gas. but it goes away if i wind it way out sometimes.

 

[old_man]

The multi wire conduction discussion here I find funny. Being an EE, at DC, the conduction is based on total cross sectional area. As the frequency goes up, the conduction tends to happen only on the surface of the wire. This is called skin effect. To combat this in the super high power RF stuff I work on, we use what is called Litz wire. It contains hundres of individually inslulated strands wove to form one cable. The nice thing is that it makes the wire very flexible. The problem is that it runs many dollars a foot.

 

[m0n3ym1k3y]

Hmmm, the O2 sensor. Well when i was under there i know im missing the last bottom bolt on the header so theres a leak but would that cause these problems because for as long as ive had it it has had an exhaust leak. Is there a way that the exhaust leak may have killed the O2 sensor causing these problems? Oh and anyone know the size of that bolt and could i pick it up at home depot or what?

 

[5-90]

Hmmm, the O2 sensor. Well when i was under there i know im missing the last bottom bolt on the header so theres a leak but would that cause these problems because for as long as ive had it it has had an exhaust leak. Is there a way that the exhaust leak may have killed the O2 sensor causing these problems? Oh and anyone know the size of that bolt and could i pick it up at home depot or what?

I suppose it's possible.

The screw should be 3/8"-16 x 1-1/4". There should be a "dish-shaped" washer under the head, if that's missing, you can use a Belleville spring washer. I consider it necessary, because iron/steel and aluminum expand at different rates, and the funky washer is there to allow for that. If you just have to use a flat washer (not really recommended...) then knock 1/4" off of the length of that screw.

For selection, I've had good luck with copper alloys (brass/bronze) on exhaust hardware, but it's not exactly something you can find easily at the local. Use SAE5 carbon steel - SAE8 is more sensitive to heat cycling, and will rapidly degrade to somewhere below SAE2 in strength after only a few cycles. SAE5 will retain more of its strength after heat cycling. I have verified this experimentally.

While you're out getting fasteners, you might want to find a 9/16" "flex" socket (short socket with inbuilt universal joint.) You'll get about an extra inch of clearance over the socket/U-joint combination, and that will save you loads of aggrivation on those lower bottom manifold screws. You'll also have more room to access the thing if you remove the airbox.

 

[Ecomike]

Hmmm, the O2 sensor. Well when i was under there i know im missing the last bottom bolt on the header so theres a leak but would that cause these problems because for as long as ive had it it has had an exhaust leak. Is there a way that the exhaust leak may have killed the O2 sensor causing these problems? Oh and anyone know the size of that bolt and could i pick it up at home depot or what?

The Ex leak would cause poor gas mileage, and carbon fouling. The fouling can eventually cause the O2 sensor to go bad, or the O2 could have just hit its expiration date. They do have a limited life.