My wife’s car developed a misfire. One of the coils was not getting a trigger signal. Tracing the cables back revealed that one had the insulation rubbed off from the adjacent fresh air intake duct.
Although the cables were encased in the braided, tough, PVC wire loom, their routing was still against the fresh air duct that moves and vibrates with the engine.
A slightly different route, or a couple more cable clamps, could have avoided this situation. But then, they did save 5 cents on each of the 50,000 cars sold in the US and Canada that year.
And don’t get me started on the defective cam chain tensioners that caused the infamous “death rattle”. It took a class action lawsuit to get that design defect rectified…