GM Camaro/Firebird 1993-1998 Repair Guide

Spark Plug Wires



See Figure 1

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Fig. Fig. 1: Checking individual plug wire resistance with a digital ohmmeter

At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring.

Every 50,000 miles (80,000 km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

To check resistance, connect one lead of an ohmmeter to each end of the wire. Replace any wire which shows a resistance over 30,000 ohms. Generally speaking, it is preferable that resistance be below 25,000 ohms, but 30,000 ohms must be considered the outer limit of acceptability. It should be remembered that resistance is also a function of length; the longer the wire, the greater the resistance. Thus, if the wires on your car are longer than the factory originals, resistance will be higher, quite possible outside these limits.

Wire length can therefore be used to determine appropriate resistance values:

0-15 in. (0-38cm)-3,000-10,000 ohms
15-25 in. (38-64cm)-4,000-15,000 ohms
25-35 in. (64-89cm)-6,000-20,000 ohms
Wire over 35 in. (89cm)-25,000 ohms


See Figures 2, 3 and 4

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Fig. Fig. 2: Spark plug wire harness assembly routing-3.4L engine

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Fig. Fig. 3: Spark plug wire harness assembly routing-3.8L engine

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Fig. Fig. 4: Spark plug wire harness assembly routing-5.7L engine

When installing new wires, replace them one at a time to avoid mix-ups. If it becomes necessary to remove all of the wires from the distributor cap or coil packs at one time, take the time to label the distributor cap/coil pack towers to denote the cylinder number of the wire for that position. When this is done, incorrect positioning of wires can more easily be avoided. Start by replacing the longest one first. Route the wire over the same path as the original and secure in place.