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Working on a 1995 Chevy Blazer which is OBD II. The issue is the ignition advance at idle is anywhere from -10 degrees and varies very much to -30 degrees. Once I hit the gas the ignition timing should go advance, but it stays negative. I had a P0325 code (knock sensor) and fixed this issue, and no codes since than, but still negative timing. According to specs, at idle the timing should be 21 degrees positive. I even put a resistor in line to reduce the dc voltage to 1.3 volts on the knock sensor circuit and eliminate it and the ignition timing is still negative. Not sure what the issue is....
The ignition timing u report is scan data? Did you check the timing with a timing light? There is actually NO way the engine would would run with 30 degrees retarded timing.
Get this resistor out of the knock sensor circuit as some computers do want to see a specific voltage created by the sensor at a specific rpm. If this signal is inhibited/suppressed by the resistor the computermight evaluate the knock sensor/circuit as faulty.
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Yes the data was from a scan tool. I have not checked the timing with a timing light yet, but can. The knock sensor circuit is good to go. I had to put in a resistor to ensure the computer is reading the 1.3 volts DC. Even if I take this resistor out and just hook up the knock sensors, no codes are found for the knock sensor circuit, but had a P0300 (random misfire) code pop up.
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