Auto Cross FAIL... (Ok, so I failed...)

Quick outline.. My poor old 1986 GTi has been giving my son some issues. The problem has been intermittent. The car is difficult to start. Stumbles, stutters, stalls. But eventually will start. Runs bad. Of course when I go to look at the car acts normal. I drive the car it seems fine. But the car got me yesterday. Drove to the track, no problem. Parked the car, started and went through tech again no problem. My turn on the track! Light turns green and off I go. Roll on the throttle to the first gate. Clear the gate as I shift to 2nd. Hit the gas and................................ Nothing.... Grab the key and frantically twist, engine cranks but will not start. Track workers grab the car and push off the track... (How humiliating! ) Roll back to the parking area, grab the few tools we have. Check the to see if the air flow plate is stuck. Nope. Check inlet boots for rips and tears. Nope. Still runs like crap. Done racing for the day. Limp home...
sigh Noted on the way home. Temp gauge goes not work. Hmmm, worked fine on the way to the track. MFA sensor is not reading the oil temp either. Possible ground problem? So I pulled both battery cables off and cleaned all the connections on both ends. No change... hmmm. I guess I need to read the book... lol

I remember many, many, MANY moons ago that I once had a similar issue with my '77 Rabbit. It turned out to be a problem with the PC board at the back of the instrument panel. In my case, a trace had burned through, which I fixed with a jumper wire. In yours, you could possibly have a solder joint that has fractured with age and vibration.

The other possibility is a bad ground in the fusebox. Those tend to get leaked onto due to rust holes in the cowl area.

Unhook the battery and go wild will break cleaner. Get the wires and hoses cleaned up. With the possibility of it being either, it will make the job a little easier.

wild will break cleaner