So after letting my car sit in my garage for a week as I waited for my insurance to switch over I didn't take it out or start it. I'm experiencing a couple problems, I'm starting to think it's the battery but It's getting annoying now. So, when I turn my car on sometimes it won't start. It will crank, give all the regular sounds it would as if it was going to start normally, but then my RPM meter drops to 0 and my battery and oil signs come on (I have a check engine light as I have taken off a O2 sensor for straight piping) I'll turn the ignition off and start it back up and it works fine I checked my battery, the negative terminal is quite loose as the bolt on it is stuck and can not be tightened... I have no idea what it could be but it's starting to really bother me.. any ideas

 

if the terminal is loose it is prob not making a good contact and not completing the circuit. get that fixed and it will prob be fine.

 

Could be a fuel pump/pressure issue.

After car has sat for several hours or overnight Try taking ignition to "ON" position and listen for fuel pump to run for couple seconds to prime rails. Turn off and remove key, Reinsert key and turn igintion back to "ON" position and let fuel pump prime again than take ignition to "Start" and see if engine fires up.

Another alternative is to have fuel pressure checked by a shop.

 

It seems once I put the ignition to 'on' position, turn it back off, and put it back to 'on' position it turns on every time I've tried turning it on with just setting it to 'on' position then starting it without doing the step twice and it won't sometimes..