Chart C4F - Dis Misfire (2.8L)

The direct ignition system (DIS) uses a waste spark method of distribution. In this type of system, the ignition module triggers the No. 1 and 4 ignition coil pair resulting in both No. 1 and 4 spark plugs firing at the same time. No. 1 cylinder is on the compression stroke at the same time No. 4 cylinder is on the exhaust stroke, resulting in a lower energy requirement to fire No. 4 spark plug. This leaves the remaining high voltage to be used to fire No. 1 spark plug. On this application, the crank sensor is mounted to the engine block and protrudes through the block to within about .050" (1.3 mm) of the crankshaft reluctor. Since the reluctor is a machined portion of the crankshaft and the crank sensor is mounted in a fixed position on the block, timing adjustments aren't possible or necessary.

1. Checks for voltage output of ignition system. A spark tester must be used, as this tester requires 25,000 volts to trigger. This checks for a potentially weak coil.
2. If the spark tester fires on all wires, the ignition system, with the exception of the spark plugs, may be considered in good working order. If the spark plugs show no evidence of wear, damage or fouling, an engine mechanical fault should be suspected.
3. If the spark jumps the tester gap after grounding the opposite plug wire, it indicates excessive resistance in the spark plug which was by-passed. A faulty or poor connection at that plug could also result in the miss condition. Also check for carbon deposits inside the spark plug boot.
4. If carbon tracking is evident, replace coils and be sure plug wires relating to that coil are clean and tight. Excessive wire resistance or faulty connections could have caused the coil to be damaged.
5. If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test could also be performed by substituting a known good coil for the one causing the no spark condition.