There is nothing like the sensation of your stomach jumping into your throat as you accelerate while your breath is simultaneously stolen by the chorus of a great techno beat. It took me a while to get my heart thumping normally after the first drive.

Don't get pulled over. The cops don't like it when your tuning on the road.

Has anyone had issues using high speed mode to write a tune to a car?

I guess Trent'* car goes through fine, mine will stop at around 50% and start timing out and going back to low speed. Haven't found anything online in this regard yet. I'm going to try it on a different laptop and see if it makes a difference.

If it'* not the laptop I'm going to have to assume it is something with my radio. The chime module starts beat boxing when you write in high speed mode. Quite freaky.

I tune my OBD1.5 pcm with Tunercats RT and an Ostrich eprom emulator.
I like this setup because I can change values while driving. There is no need to key on/off and flash.

No problems here.

Found the problem. Door chime module must be messing with the data. Door chime module unplugged, everything goes smoothly. Looks like I've got another switch to put in.

Figured I would mention my findings with HP Tuners and the switch I put in. Just putting the switch in seems to have fixed the problem, which doesn't make a whole lot of sense to me. I put the switch on the data wire going into the module. It originally had two data wires connected to the same pin. I soldered those two together, ran them into a switch and back into the module. My first try with the switch off gave me problems, couldn't read the pcm. Then it wouldn't read with the switch on either. I reset everything and left the switch on, now I can write in high speed even with the module on and it quit making noise like it used to. So all appears to be good for now.