Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2007 Chevy Silverado Classic 1500 4.3L: Will not go into closed loop
Subject vehicle came in with a cylinder 5 misfire. Truck has over 200k miles; owner had already changed plugs, wires, and ignition coil, but still had the misfire.
I scanned the computer and there were a lot of DTCs, so I cleared all codes to see what would return.
I got a P0200 (injector circuit open) and a P0300 (random misfire); when I looked at misfire counters; only cylinder 5 was incrementing. I found the cylinder 5 injector was open, so that will get changed once I verify the PCM driver circuit is working.
All of the O2 sensors were replaced with OEM sensors, but the engine will not go into closed loop with a warm engine; engine temp reads normal on the gauge and on the scan tool.
What other parameters are needed (besides a hot O2 sensors) for the PCM to go into closed loop?
You guys were spot on!!! I changed out the faulty injector (buried under the intake manifold ... I mean come on GM; who makes these decisions on injector locations???)
Anyway, I cleared the DTC for the #5 injector, and right away my fuel trims were showing activity.
