Replaced wires with ACDelco, regapped AL-605's to .055, moved and replaced coils, swapped wire terminals, cleaned crank sensor, cleaned all sensors, I.A.C., etc. swapped evap, cleaned PVC, checked for vacuum leaks spraying carb cleaner, spritzed wires checking for arcs, cleaned MAF, swapped MAF with other used MAF, cleaned and heat sink compound the ICM, swapped ICM with used one, cleaned ICM connectors with contact cleaner, ....
Checked and cleaned battery ground and ICM ground under bracket, checked injector resistance, swapped injector, put new O-rings on injectors, checked fuel pressure with existing gauge on billet fuel rails, pulled PCM and checked and cleaned the connectors, checked for broken or suspect wires, O2 sensor was replaced in 2009, (not sure on this one yet) otherwise....no change.
Aeroforce gauge shows 70-100 misfires, then drops to 20-40, then 0, back up to 80-100 misfires on #4
cylinder. Then light is popped, Aeroforce shows PO300, random misfire, but all on No. 4 cylinder.
Dig up HP Tuners, (haven't used it in years) and run scan. Looks like everything working but I've forgotten most of what I learned, as the car always ran great after the original final tune with it. It does show a PO102 code with the PO300, which is a "MAF Sensor Circuit Low Frequency (Immature)" so I swapped the MAF's again and recheck the wires. No Change. Swapped back to original MAF and then it went away...? Reload Calibration to PCM, no change.
I also notice in the DTC box, lower right, in the "Once per trip Tests" it showed the Oxygen Sensor and Heater as "Incomplete" in red. Now it just lists the O2 sensor "Incomplete" Is this saying the o2 sensor is dead? I'm seeing activity on the scan...?
I'm at my wits end on this and open to any suggestions!
Ok, scan now loaded, 6-3-2016......
Edited by WaterDog, 05 June 2016 - 12:03 PM.