I have a 1993 Honda Civic LX. The car quit running over a month ago and just sat, so the battery was low. I charged it over night and I'm getting 12.95 volts.

Here's what's done to it.
Auto to manual conversion. I soldered the two black wires together that connected to the shifter and removed the blue box.
Swapped a B18C1 in so I ran the two wires for VTEC.
Installed a PLX wide band O2 sensor and ran the wide and narrowband inputs into the ECU. Narrow in the original narrowband input, wide band in the EGRL input. The instructions say to run a wire from the O2 signal wires through a capacitor and to the ground pin D11.
The PLX O2 sensor is grounded through pin D11 on the ECU (I'm going to try disconnecting that and grounding it elsewhere).

Last night I hooked up my laptop and turned the car on and the ECU would show up and when I went to upload, it gave me an error message and said to try again. I tried for a while and I was noticing the clock was sort of dim. I charged the battery over night and when I tried again, the light from the S300 turns on when I turn the ignition on, the ECU shows up and then the light quickly turns off. I tried both a P28 and a P72, both are doing the same thing.

Is there something I did wrong with the wiring, or that I didn't do in the auto to manual conversion? Is the battery bad?

 

You need a new battery.

 

That's it? Is that just a guess or you're certain about it?

 

Pretty certain that's the problem, but if not THE problem, you still need a battery as 12.95 volts in not fully charged. Should be around 13.8, and shouldn't go dead that easily..

 

Alright, thanks man. I'll go get one in the morning. I wasn't doubting you, just want to make sure before spending money on a new battery.

What happened what I drove out of town, shut the car off and when I tried to restart it, the car wouldn't keep running. Turns out I blew the original D15B7 it had. I kept trying and trying because it was like 11pm. Well, it wouldn't start and cranking it just wore it down. I wanted to avoid sleeping in my car overnight, which is what ended up happening and why I'm glad I have full interior and the back seat. I got it towed home, it sat and sat and yeah.

 

The new battery and tightening my ground wire on my thermostat housing fixed the problem.

 

Amazing what proper voltage & grounds can do :-)