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1997 Toyota Tacoma 2.4 P0300 Misfire

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6 years 2 weeks ago #20321 by bluejeans27
This Toyota had multiple issues which I have been systematically addressing. O2 Sensor not switching, Fuel pressure to high (regulator), Bad Cam Signal waveform caused by aftermarket Distributor, Coolant Temp Sensor for ECM Dropping out (broken sensor), ect. After repairing each issue ECM still sets a P0300 (random cyl. misfire). No misfire felt though at idle or under load. Looking at scan data P0300 will set at idle or at 2100rpm, showing misfire on cyl. 2 and 4. I have performed just about every test possible from static compression, running compression, verifying timing, Checking valve adjustment, fuel pressure spec, Fuel Injector drop, ect. Also have scoped everything from Cam, Crank, IGT, IGF, Coil Ground, Secondary Ign, Injector Control, ect. Substituted a known good ECM and Igniter with no change. There must be something in these these waveforms that I am missing. The IGT (Ignition Timing/Trigger), IGF (Ignition Feedback) waveform shows the Timing/Trigger event happening after the coil has already begun charging. Not sure if i am looking at that right. But that would mean something else besides the ECM is Triggering the Igniter/Coil. Can anyone make sense of that? I also attached the clean Cam (OEM Distributor) and Crank signal waveform that to me looks just fine. I know the ECM is using the Cam signal for the Ignition and Injector timing and the Crank signal for engine RPM and Misfire Monitor, but again im not seeing any issue in that waveform. Any suggestions on what would cause this P0300 Misfire would be much appreciated. I can also upload any waveforms someone may suggest for further examination.
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