t4 2.5 petrol emissions through the roof.

[adyjoad]

Hi all need some help please, my T4 has failed the MOT dismally on emissions. CO is 10.2+, hc's are around 300 and the Lambda is around 0.7. It's a 1995 2.5 petrol ACU engine and only done 55,000 from new. Less than 3,000 miles ago it's had a new cat and lambda probe and I've just changed the 2 water temperature sensors. All parts are genuine VW. When you drive it it has a very bad surging on light throttle and a distinct flat spot. A fault code reader came up with no faults detected so I'm stumped. Anyone come across this before or got any advice?

Cheers
Adrian

[adyjoad]

This thing is still playing me up, managed to put it on a VW computer and it says that the injectors are pulsing for too long and that the Lambda sensor voltage drops to zero intermittently. As it does this on tickover the engine stumbles and then recovers. Anyone got any ideas?