I have a 91 civic si ed7. Bought it with a b series swap and a partial wire tuck.
Started having an issue. When I hit a bump in the road my stereo would lose power and restart. Also my headlights and clock would flicker.

Things I've done:
Replaced power wire from battery to main fuse box.
Checked fuses.
Installed a better ground on the stereo(before I noticed the headlights flickering).

It's gotten progressively worse over the last few weeks. I did some research but I know very little about electronics. Can't afford to take it to a shop right now. I can't seem to find any main grounds or any diagrams for them. Any suggestions would be greatly appreciated. Thanks.

 

Check the ground cable.
Grounds are just as important as the power cable.
Sounds like a loose connection.

 

I checked the battery, valve cover and transmission grounds. The thermostat ground goes into a wire cluster and into the cabin. Do you know where it grounds for certain because I can't find it.

 

Checked all the grounds. Even got a manual via email from a friend to track them all down. As it turns out, when the engine swap was done they moved the transmission ground. It was firmly in place. Unfortunately the paint was only sanded off to the grey primer. Easy enough mistake considering the color, but damn...... whole lot of work to find something so simple. Lol