hi all, i fancied a spin in my '91 tt auto zed today so i took it down the motorway for a good sunday thrashing. at one point whilst accelerating, the engine hesitated,almost as if gearbox couldnt decide on which gear to use, i took foot off throttle then accelerated again and the whole car started to shake and felt powerless. within seconds of this happening the cat warning light came on so i pulled over, once car was at idle it sounded like it was missing until when i popped the bonnet and wiggled a connector right beside the oil cap the engine seemed to sort itself out!? i started driving car again and all seemed fine for a while, but 15 mins later it happened again! really annoying as iv got o idea what the problem is and how to fix, can anyone help? cheers guys.

You've found the problem....its a poor connection to either the PTU or Coilpacks.

 

The catlight neans unburn fuel is getting into the exhaust system and iginiting, so you have a missfire to fix.

 

Go around all the coilpack connectors , take them off and clean them. They are probbably corroded. Do the same for the PTU connectors.