Hi!
I have 89 s2 rs turbo and just got plates today.
Car runs quite ok when driving without no boost under 0 psi.
When i press the gas and the boost starts to rise the car goes so lean that the normal afr meter goes off the range lean so i stop immediately the boost rise. I can feel the car does not run correctly under boost.

Coupe of checks i did made:

-Ignition advance is correct
-Gas return line removed and measured in bottle, i think fuel pump ok.
-New spark plugs
-All hoses ok, no leaks.



Any ideas?

The car is stock except kent 35 cam and 2.5" free flow exhaust, standard air filter etc.