Back story, I have a 1999 3.0 gas Ranger. 197,000 miles. Need to smog, California. I did an oil change and disconnected the battery, filter right by the starter. Connected battery and now check engine light is on. Code reader says mis-fire cylinder #1. Replaced the plug, proper gap, replaced the wires with new, checked for spark with plug spark light tool, checked the plug outside the engine, grounded to block, had spark. Injector was reading 0 ohms so replaced with new. Checked it with meter 16k ohms. Checked the red wire on top of injector, 12 volts, Checked the white wire on top of the injector with test light, connected to positive side of battery, engine running. Test light flashing. Used a modified stethoscope to listen to injector, it was ticking/working. Starts right up, no evidence of missing, running rough, still reads mis-fire cylinder # 1? I haven't done a compression check, tool arrives tomorrow. Will low compression cause the computer to say mis-fire cylinder #1? Do I have a computer that is starting to fail? 1999 to 2021 and high mileage. Never had problems, been a great truck, garaged last 20 years. Would really like to keep it on the road. Any input would be appreciated. Thank you.

 

Had that happen to me on a Monte Carlo once a long long time ago. Everything was fine, except the battery was weak, so I changed it. Put new battery in and started right up. CEL was on now... ran code, said multiple misfires. That's weird I thought. Was idling fine. Upon some advice, I disconnected the battery. Turned the key over as if I were trying to start it, for about 10 sec. Hooked battery back up, restarted and voila! Light off. Never came back on.

 

Are you able to reset / clear the code? Does it keep coming back?

 

Thank you for reply. I wii try that tomorrow.

 

Thank you for your reply. I will try that tomorrow.