This is really frustrating me now. I am wondering if one of the more obscure packts I havn't dealt with yet needs a return of some kind.

I'm pretty sure it's not an ACK issue though, because if I start the program just before a car crosses the line I still do not get the LAP packet.

LFS just isn't sending the data, and I dont understand why :/. I might soon run the assumption that my code is in some way wrong and rewrite it from the ground up.

I have found the stray packets ! YAY!

It turns out that lap packets are 92 bytes aswell as outguage which I didn't know, and the way I had structured the check for a valid OutGuage packet was discarding the LAP packets as corrupted without reporting the written off data. Something i'd done in the first outguage mod that this started out as before I added insim support :/.

Glad to hear you've found the cause Screams for a Super Spammy Debugging Mode(TM) though, where everything gets dumps to stdout