In my 1995 6 Speed Standard Transmission Z28 Camaro, it makes like a loud bang under the car on a startup, cold or not it will most of the time make the loud bang. So my first question is, can it have something to do with the catalytic converter? Or could it be something I’m unaware of? Need help finding out what the problem could be and if it needs some immediate attention.
How many seconds does the bang/thump happen after the engine fires? I would think it would take quite a few seconds for the cat converter to get hot enough for an overrich mixture to "light off" with a "whump. Since you don't have OBDII, it's harder to get info on that issue - maybe a *tuner* shop could help with that. If the bang/thump comes right away, you need to look at the driveline, especially engine mounts.
Yeah it does happen right away as soon as the car turns on. Thanks for the help.