I agree, the wet plug is suggesting a no-fire (or perhaps a problem with combustion). I am curious if the injector is stuck open. Sadly the 3400/3100 requires more effort to get access to the injectors (the upper intake actually covers them). So even though I am fairly certain he needs access to the injectors, I am all for some additional quick/easy tests to have a better idea what is going on. If this was a 3800, those injectors are right there and easy to mess with.

I know I suggested double checking the gap, but another thought I don't think I saw, swap the plug with another cylinder. Could be a bad plug. Another quick/easy test.

 

Alright, starting fluid test didn't get me anything, I had to log the misfires on my phone, hold the throttle cracked open, and spray the fluid. I opened up the connector by the alternator and tried probing the wires with no success, I need to find a wiring diagram so I know which pins to hit, but even then I'm not sure that my multimeter leads are able to hit the metal in the sockets. Seems like it'll be time for disassembly soon.

 

If you have never changed the intake gaskets now would be the time. They fail all the time. There is a forum on Facebook about 3.8s. Even though that is not exactly what you have, I bet someone could help.

 

I assume you were spraying the starting fluid under the upper intake (so if there is a poorly sealed injector that fluid would get sucked in to it)? As for the leads on the multimeter, get some paper clips, they are perfect to put into the connectors and extend the connection (heck, helped me figure out an O2 sensor issue that was related to a failed female pin not making contact anymore). But you will need the wiring diagrams to handle it. I think one pin is ground for all the injectors.

 

Fantastic idea, that should help a lot. I was spraying under the upper, kinda straight down onto the injector, almost like I was trying to flood the lower intake. Any idea where I might find the wiring diagram? Maybe a dealership?

Greyghost, when I did the head gaskets I changed every single seal and gasket from the heads up, and got some metal lower intake gaskets even.

 

Good man. I learned about these V-6s the hard way. After my 05 Supercharged MC, I moved up to an 06 LTZ, which is more like an Impala. Not the same car, but agile and not expensive to maintain.

 

Some dealers offer the diagrams free, would not hurt to check there. Or might be able to google search it.

 

I never got a chance to get a wiring diagram, but I had planned to pull the UIM today anyway to clean the #3 injector, it ohms at 11.9 while 3 others are between 12.2-12.5 so that concerns me, there's a brownish discoloration on all the injectors but it's a bit worse on the number 3. I'm gonna clean it out and swap it to the #4 position as I reinstall.

 

I would almost be inclined to outright replace that injector. All things being equal, that seems to be a very weird coincidence that it ohms significantly less than the others. Also, make sure to lube the o-rings when you re-install. GM recommends a drop of motor oil. Since you are swapping the injector position, I hope the problem migrates to cylinder #4 and if it does, you have the culprit.

 

I meant to update sooner, lost track of time. I ended up just outright replacing the #3 injector and the car ran better, but not quite like it should, then over the course of two days its running worse than it was before the injector swap... I'm so lost here.