I have a 96 lumina 3.1 v6. Check engine light has been on for over a year bit ran great so didnt bother. Now will not pass emmisions inspection so must get fixed. obd scanner shows misfire on cylinder 3 and you can watch the misfire counter rackup on the screen. There arent many misfires but after a day or two check engine light comes back on with same code. So far replaced plugs and wires,ignition coil and now just replaced all fuel injectors and still has misfire but doesnt happen as much but still enough to bring check engine light on after a couple of days. I am not losing coolant so I think I can rule out a small head gasket leak. I am going to get an emmisions waver because of the money I have spent so far goes over the threshhold of $450 but this is a one time waiver. I dont know what else I can replace other than the engine or possibly the ecm. Please Help!!!!!!!!!!!

I have a 96 lumina 3.1 v6. Check engine light has been on for over a year bit ran great so didnt bother. Now will not pass emmisions inspection so must get fixed. obd scanner shows misfire on cylinder 3 and you can watch the misfire counter rackup on the screen. There arent many misfires but after a day or two check engine light comes back on with same code. So far replaced plugs and wires,ignition coil and now just replaced all fuel injectors and still has misfire but doesnt happen as much but still enough to bring check engine light on after a couple of days. I am not losing coolant so I think I can rule out a small head gasket leak. I am going to get an emmisions waver because of the money I have spent so far goes over the threshhold of $450 but this is a one time waiver. I dont know what else I can replace other than the engine or possibly the ecm. Please Help!!!!!!!!!!!
sticky valves will do that,, put a bottle of gumout injector cleaner in when you fill the gas tank do that regular every tank for a while.. it will clear up...iv been there..

Thanks, I have allready begun to add the injector cleaner every fillup and will continue this regimen to hopefully clear the problem. If you leave the obd scanner hooked up and go driving it shows no misfires while driving. You will only see the small misfires when stopped at a light or in park. Does this make sense?

Thanks, I have allready begun to add the injector cleaner every fillup and will continue this regimen to hopefully clear the problem. If you leave the obd scanner hooked up and go driving it shows no misfires while driving. You will only see the small misfires when stopped at a light or in park. Does this make sense?
thats what it is, you can also spray just a little brake fluid in the cylinder after you take the plug out.. very little fluid let the car sit over night... use gummout injector cleaner every tank .. if you got bp gas where your at use it for awhile..i use it only when i need to get the valves clean. the valve is gumed up thats why the light comes on at idle... this will free it up...let me know in a month ok..

It could be a weak head gasket seal on that cylinder too. I'd do a compression test, both with the engine cold and with it warmed up to see if that cylinder is lower than the rest. If you're losing coolant, you could also have the infamous intake leak that plagues the 3100, and coolant is getting into the cylinder from that, causing it to miss. Check your coolant level, and your oil. If the coolant is low and/or the oil is cloudy and/or overfull, it's intake gasket time.

One other unlikely thing to check. On my 92 Lumina I had to replace the Ignition plate behind the 3 coils, it was causing a misfire on only one cylinder for some screwed up reason. I replaced the coil for the affected cylinder and had the same problem, but once I replaced the plate behind the coils the problem resolved.