3100 issues

[mpark02]

Hey guys, 1st time poster here, i'm having a bit of a problem with the 3100 in my 95 Grand Am. Every few weeks i'll start it up and it will run real rough, noticably missing on one cylinder and the engine will shudder back and forth much more than normal. I've managed to narrow the problem down to the center cylinder in the back bank (#3 or 4, not sure) by removing each spark plug from the coil and listening to the tone of the engine. By removing the plug for that cylinder, there was no difference in idle speed but there was with other cylinders. Anyway, i've managed to get around this problem by giving the fuel rail a little tap with a blunt object near the cylinder and it clears right up, only to happen a few weeks later. I'm fairly convinced its either a loose connection to the injector, or there is crap in the fuel rail that prevents fuel from flowing to that injector. I've also replaced plugs, wires, and tried several different types of fuel injector cleaners and the problem always comes back. Anyway, i was just looking for a little input to see if anyone agrees with my diagnosis before i start tearing the intake manifold off to start futzing with it. Thanks for any input in advance

Mike

[geoffinbc]

Remove and inspect that injector connector. Check the coil pack (#3 if it is the back bank) and look for any rust on the terminal.