Question about 1998 Subaru Legacy
Have DTC Code PO101, a miss fire in cylinder #1. I have inspected the spark plugs but all are in good condition. A tune up was done approx. 30k miles ago. The fuel filter was slightly restricted but just barely. The wires ohmed out within spec's. Originally, had a PO103 code along with a PO325 knock sensor code. Resistance was out out range and replaced the sensor. The resistance on the coil reads good but I haven't seen it on the scope. I don't have a scope to see and read the ignition patterns. The resistance at the injector is good, 11.5 ohms.
problems occurs after the car warms up and intermittently. what am I missing?
Tips for a great answer:
Inspect the EIS towers and plug the wire connections for corrosion or other signs of poor retention at connections.
The electronic ignition (EI) module supplies a signal to the PCM whenever it determines that the #4 cylinder fired on its compression stroke. Because of opposite coil tower polarity, the simultaneous fir of #1 and #4 cylinders are of opposite polarity as well. Under most conditions, except decel, the waste spark cylinder fires before the compression cylinder in sequence. The EI module can determine this polarity sequence and voltage amplitude by using capacitive pickup plates located under the 1/4 coil. If the module senses a positive to negative sequence and high negative spike when #4 is on TDC, it pulls the PCM cam signal to ground signaling that #4 has just fired on compression. This signal along with the double pulse received from the CKP sensor, synchronizes spark and fuel timing.
Beside plugs , plug wires need to be replaced as well !
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