Engine - Electrical Connections and Grounds

The electrical systems in most cars were designed with a certain amount of blind optimism. Crimped connections, unprotected bare copper connectors, and small gauge wire, all indicate that the vehicle manufacturers did not plan for people to be using their products after 20+ years, or to use those products in a world full of rain water and puddles, or an engine compartment full of dirt and grime.


Ground Straps
The ground straps in the engine compartment are a good example of what is described above. The engine is grounded between the intake manifold, head, transmission, and chassis, with 18 gauge wire, crimped bare unsoldered copper terminals, and the connections are probably covered with 20+ years worth of filth and corrosion. These ground straps are the return path for all those sensors and solenoids in the electronic fuel injection system, and also the return path for the electricity sent through the ignition coil to the spark plugs. If the engine is difficult to start and sluggish to respond, chances are that poor grounds are a significant contributor to this problem. It may sound like overkill, but directly replacing those tiny ground straps with 8 or 10 gauge audiophile amplifier ground cable (the expensive silicone stuff), with crimped and soldered, gold plated terminals, will improve grounding tremendously. Also, take the time to tap out the ground bolt holes, replace the bolts with stainless steel bolts (to prevent corrosion), and apply dielectric grease to the threads of the bolt and the threaded hole.
The ground wires in the wiring harnesses are also worth a good look. They are also unsoldered, bare copper, and probably filthy and corroded. Replacing the terminals with small, gold plated terminals, soldering the connection, tapping the ground bolt hole, using a stainless bolt, and applying dielectric grease, will help a lot here also. Take this technique through the entire car, and pretty soon you will find that the engine starts on the first turn of the key and the head lights and tail lights are brighter.

Soldering Electrical Connections
There are a number of large electrical connectors between the engine and the ECU, as well as between all of the wiring harness sections. None of these were originally soldered, and many of them would probably benefit from being cleaned and soldered.

Wire
The wire used by the vehicle manufacturer in Geo Storm cars is pretty high quality. It is fine strand, flexible, with high quality copper and insulation.
By contrast, what is commonly classified and sold as “Automotive12 Volt” wire is garbage. The strands are large, coarse, stiff, and made of poor quality copper, that does not solder well. The insulation is hard and often brittle, breaking and flaking off in large pieces.
In the event that a wire must be replaced, or a wiring harness must be made from scratch, it is highly recommended that “Hook-Up Wire” be used. This wire is separated into two different groups: 300 Volt Multistrand and 600 Volt Multistrand. These are really the same, but the wire is divided into two groups based on size. The finer gauges (26-18 gauge) are 300V, while the heavier gauges (16-10 gauge) are 600V. When compared to Automotive 12-Volt wire, Hook-Up wire is rated for 15-25 degrees Celsius higher temperature, and is far more flexible.
For ground straps, battery cables, and large power wires, it is recommended to use audiophile power cable, usually described as silicone insulated and oxygen free. When used in the engine compartment and on the engine, use heat insulating sleeves, such as those commonly sold for protection of muscle car and hotrod ignition wires.

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