Chart C-4D-1 DIS Misfire at Idle: VINS 1 K R & U

Fig. 009 Chart C-4D-1 "DIS" Misfire At Idle 2.0L (VIN 1) "J" Series & 2.5L "A & N" Series:

Fig. 010 Wiring Diagram for C-4D-1 "DIS" Misfire At Idle 2.0L (VIN 1) "J" Series & 2.5L "A & N" Series:

CHART C-4D-1

"DIS" MISFIRE AT IDLE 2.0L (VIN 1) "J" SERIES & 2.5L "A & N" SERIES




Circuit Description: The "Direct Ignition System" (DIS) uses a waste spark method of distribution. In this type of system, the ignition module triggers the #1/4 coil pair resulting in both #1 and #4 spark plugs firing at the same time. #1 cylinder is on the compression stroke at the same time #4 is on the exhaust stroke, resulting in a lower energy requirement to fire #4 spark plug. This leaves the remainder of the high voltage to be used to fire #1 spark plug. On the 2.5L application, the crank sensor is mounted to the bottom of the module/coil assembly and on the 2.0L (VIN 1) application, the sensor is remotely mounted beside the module/coil assembly. The sensor protrudes through the block to within approx. .050" of the crankshaft reluctor. Since the reluctor is a machined portion of the crankshaft and the crankshaft sensor is mounted in a fixed postion on the block, timing adjustments are not possible or necessary.



Test Description: Numbers below refer to circled numbers on Diagnostic Chart
1. If the "Misfire" complaint exists under load only, the diagnostic chart on page 2 must be used. Engine rpm should drop approximately equally on all plug leads.
2. A spark test such as a ST-125 must be used because it is essential to verify adequate available secondary voltage at the spark plug. (25,000 volts)
3. If the spark jumps the tester gap after grounding the opposite plug wire, it indicates excessive resistance in the plug which was bypassed. A faulty or poor connection at that plug which was bypassed. 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 coil 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.