Oldsmobile Questions? Ask a Mechanic for Answers ASAP
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I'd start by double checking firing order incase you mixed up a wire. If that is fine then you probably have a bad injector. You can swap injector 1 with another cylinder to see if misfire follows injector, if so replace. I'd also reset codes again to see if cylinder 1 is the code that comes up again before swapping around injector. Here are replacement instructions and firing order diagram. Let me know if you have more questions, thanks.
Only other thing would be engine mechanical such as valves or piston rings and a compression test would verify that. Let me know if you have more questions, thanks.