I was throwing parts at my cylinder 1 misfire before I found the issue. Replaced coil,plug and wires. Next steps were compression testing and leak down testing. I had a very hard time with the first attempt at compression testing as I couldn’t get the tube threaded in the plug.

I viewed about 50 videos on YouTube and some suggested checking the injectors before removing the valve cover and heads. I put a long pry bar on injector to listen for the ticking and heard nothing on. Nothing on the multimeter, injector 2 & 3 show 16.4 ohms.

So my question is, do I replace the one injector or do I need to replace the set?

Hopefully, my troubleshooting helps someone having a misfire issue.

 

Just need to change the one injector, it is not a common failure, so other injectors should be fine.

1999 3.0l used two different injectors, smaller ones for Gas Only engine and larger injectors for Flex Fuel
I think Gas Only were 14lb, and Flex were 22lb

Injectors are NOT the same as Jets on a Carb, lol, i.e. larger injectors do not give you more gas/power.
Its what fuel flow the computer expects when opening an injector for say 100milliseconds
If you put on larger injectors then computer will just set RICH code because too much fuel was flowing into engine so it had to cut down the Open Time by more than 20%, over 20% sets a code.

Ethanol is a weaker fuel than gasoline, so computer must added 10-20% more fuel to the engine if running E85, which is why Flex Fuel engines needed the larger injectors