Service Engine Soon - #2 Cylinder

Hey guys, I have used this forum for many answers to questions I have about my 99 Lumina and have had great success! Thank you all.

I am now starting to get a check engine light, blinking, and the car is running a little ruff. I have the luxury of having a diognostic tool to check my codes, and the error I got was the #2 cylinder misfiring, so I figured I needed to change the plugs and wires. It has been about 50,000 miles since it was last done, so I figured no big deal. I hate doing this on a Lumina for obvious reasons. When replacing the plugs I noticed the #2 plug was discolored from the rest of them. It looked like it has not been burning fuel, as it was damp with oil/gas. Is there not enough combustion?

Long story short, the light came back on after the plug swap and the #2 cylinder is still misfiring. Can anyone with experience with this help? I guess I can take it to the local dealer, but I don't feel like being taken for a ride. If it is a fuel injector valve, could this be done by me? Any help would be greatly appreciated. Oh it has 107,000 on the OD.

Thanks in advance!

There's a good chance you have a bad injector. It's a fairly common issue on GM 3.1 VIN-M's, not as common on the 3.8 VIN-K in the Lumina LTZ . Doing an injector balance test with an ohm meter would definitely put the finger on the injector if the #2 injector is out of spec with the other 5. You could also test the injector harness with a noid light to be sure the injector is receiving a signal from the ECM. The biggest issue is that the upper plenum needs to be removed to gain access to the injectors on a 3.1, but it doesn't on a 3.8 if you have that engine.

start with the basics, I hate to say this, but I'd remove all plugs again, unplug the ignition module, and check compression of all the cylinders and compair. Lets make sure cylinder number two has agequate compression before you start ripping the intake plenum off.

Today I checked the injector harness with a noid light to be sure the injector is receiving a signal from the ECM and everything is good. It is receiving a good signal. It must be the injector or a slight compression leak, I think. Actually I am pretty sure it is just a malfunctioning injector, because I put a tank of Shell plus in and some injector cleaner and I am not getting any more shakes, engine lights, or sputtering of any kind. I also think it may have to do with the fact we put some Giant Eagle "Get go" gas in. I have heard that the quality of their fuel is sub-par. If I continue to have problems I will probably have to change the injector.

Question: If you change one injector, they tell you to swap them all, does this really matter? Can you just fix one?

You can change injectors individually, so if only one is bad, you don't have to replace them all. You may have learned an important lesson in using generic branded gas. Stick with top tier branded gas, and avoid any ethanol blended crap.

I had the same problem replaced the plugs, wires, coils, and control module. Finally replaced the injectors and all is running smoothly now.

Not really a mechanic so it took me about 3 hours to replace them.