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I'm going to try this again. I'm having ONE extremely minor issue with my car at the moment, and I'm asking you guys to help me diagnose and solve the problem. I'm at my wit's end, as it doesn't seem to be an equipment failure, it seems to be one of those electrical gremlins that I have been playing hell trying to find.
The symptoms are:
-Intermittent DTC 16 (Optispark Low Resolution Pulse Failure); Triggered when High Resolution Pulse is detected, but Low Resolution Pulse is not.
-Hard Start-Cranks for 4-10 seconds, will ALMOST start, then try cranking again, will crank 2-3 seconds, then fire right up.
The DTC 16 alone is enough to turn the LT1 into a paperweight, and 9/10 times, it's the omen of a dead optispark, as a constant DTC 16 will kill fuel and spark, and the engine will not run. This is NOT a bad optispark, symptom has persisted through 2 Optisparks, including replacement Opti harnesses both times.
The odd part of my symptoms is that the DTC 16 is triggered every time the key is turned on, but before the engine is started/cranked. Even if I clear the code with key on/engine off, it persists. This leads me to believe PCM failure or a wiring issue, but I'm not even sure where to start. I've cleaned the engine grounds at the pass. wheel well and ICM stud, no change.
A friend helped me when I replaced the opti, plugs, wires, compression test, etc., and he found a bad looking ground at the ICM stud (the ignition wiring harness grounds, two yellow wires and one black wire), which was crimp-connected to a ring terminal, which was then attached to the ICM stud. He removed the crimp connector, soldered a small piece of 16-18ga wire to the 3 wires to lengthen them, soldered a ring terminal to that wire, heat-shrink and electrical taped it all up, and attached it to the ICM stud. It looks much cleaner, but I'm concerned that he may have used too small a wire gauge to ground the ignition harness properly, leading to false detection of a pulse signal. Is that possible?
I haven't checked fuses, inspected the harness at the back of the engine yet, nor pulled the PCM to check. I don't yet have a spare PCM, so I unfortunately cannot swap it to verify a PCM issue. I've been told a low voltage condition could cause these issues, so I'm leaving the battery on the charger tonight, and I'll check for the code at key on/engine off again in the morning.
Any input is appreciated, as I'm sure there are other possible causes that I may not have considered.
The symptoms are:
-Intermittent DTC 16 (Optispark Low Resolution Pulse Failure); Triggered when High Resolution Pulse is detected, but Low Resolution Pulse is not.
-Hard Start-Cranks for 4-10 seconds, will ALMOST start, then try cranking again, will crank 2-3 seconds, then fire right up.
The DTC 16 alone is enough to turn the LT1 into a paperweight, and 9/10 times, it's the omen of a dead optispark, as a constant DTC 16 will kill fuel and spark, and the engine will not run. This is NOT a bad optispark, symptom has persisted through 2 Optisparks, including replacement Opti harnesses both times.
The odd part of my symptoms is that the DTC 16 is triggered every time the key is turned on, but before the engine is started/cranked. Even if I clear the code with key on/engine off, it persists. This leads me to believe PCM failure or a wiring issue, but I'm not even sure where to start. I've cleaned the engine grounds at the pass. wheel well and ICM stud, no change.
A friend helped me when I replaced the opti, plugs, wires, compression test, etc., and he found a bad looking ground at the ICM stud (the ignition wiring harness grounds, two yellow wires and one black wire), which was crimp-connected to a ring terminal, which was then attached to the ICM stud. He removed the crimp connector, soldered a small piece of 16-18ga wire to the 3 wires to lengthen them, soldered a ring terminal to that wire, heat-shrink and electrical taped it all up, and attached it to the ICM stud. It looks much cleaner, but I'm concerned that he may have used too small a wire gauge to ground the ignition harness properly, leading to false detection of a pulse signal. Is that possible?
I haven't checked fuses, inspected the harness at the back of the engine yet, nor pulled the PCM to check. I don't yet have a spare PCM, so I unfortunately cannot swap it to verify a PCM issue. I've been told a low voltage condition could cause these issues, so I'm leaving the battery on the charger tonight, and I'll check for the code at key on/engine off again in the morning.
Any input is appreciated, as I'm sure there are other possible causes that I may not have considered.
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