Tuning Box and clutch slip!?


New member
S Wales
Polo GTI 1.8 6C
I have this weird issue with my TMC Motorsport tuning box which I had on my previous 1.2 tsi which I got reprogrammed to my Polo 1.8 tsi 6C manual(EA888 Gen3)...I know it’s not a Golf but we share a similar chocolate clutch, anyway...

I plugged in my box turned it on, all was great felt more power especially In 2nd/3rd. I went on the motorway put my foot down and revs started to jump but the car didn’t move...typical clutch issues. I pulled over turned the box into ‘off mode’ where I felt no additional power but it was still having this issue. I removed the box and the issue is completely gone. I contacted TMC motorsport to say I was having issues and to clarify whether ‘Off mode’ provides any additional power to which I was told no!
So I don’t understand what caused this but it hasn’t occurred since. Maybe the box did provide extra power.
Anyone got any thoughts on this?