DME Almost Fried During Flex Fuel Wire Install

I had a major scare the other day. In the pursuit of speed I decided to upgrade the BMS JB4 unit I have for my N55 engine to have the capability of detecting E85 and adjusting the DME accordingly. It should be good for somewhere around another 40 to 50 hp / tq.

I had to expose the wiring harness of the JB4 unit and first snip two wires. I then had to wire one side together and wire the other side together with an additional sensor that connects to the fuel rail. This sensor has a pin that then goes into a DB25 connector that plugs in to the JB4 unit. Scary stuff. I did everything as outlined in the instructions. I read the thing about 10 times to make sure.

Once all done I tried starting the car. It took a long time to start...then engine light...then dead. After this happened a high pitched ringing sound came from the car speakers until the battery was unhooked. Immediately I had a ball in my throat and felt ill. After quickly disconnecting the battery I rechecked all of my connections. The worst part was that I knew for a fact I had done everything right. The moment you realize everything was done properly is the moment you no longer know what to check next. I emailed the vendor and they quickly got back to me with some things to try. The first round of communications was the usual, making sure I wasn't retarded. During this back and forth I decided to just reverse everything and carefully inspect every part.

It's hard to see in the picture but it shows the problem. The flex fuel add-on module they gave me had one pin that was not completely seated. When connected to the fuel rail it just pushed itself out the back. I pushed on the corresponding wire from the back of the plug and it clicked into place neatly. At this point I was breathing an apprehensive sigh of relief. I still didn't know whether I had fried anything. I was so eager to try this fix that I scratched the shit out of my hand reaching back to the fuel rail connector.  I look like a burn victim. I hooked everything back up and the car started up as though nothing had happened. No issues so far but I still haven't driven out of the garage due to weather. I remain confident though at this point. A very scary moment but it's all worth it in the end. It's just part of the ups and downs of what we do. I also learned that every component, no matter how much you trust the vendor, must be inspected very carefully.