Hi guys... Im from South Africa. Drive a Astra G OPC
its a Z20LET engine...
Engine is stock.. but i have this flat spot... When i start the car early in the morning, and i wait for the engine to warm up... it runs perfect! very strong.. But when it goes over to the running map.. +- 70deg cel. then i have this flat spot between 3000 - 4000 rpm... after 4000rpm it pulls like a deamon again!
I have replaced a AFM about 6months ago. After a bodyshop damaged my afm by starting the car in the Hot bake oven after a quick paint patchup. Had to get a used AFM to clear the Error code.
I dont think it is boost related.. the turbo still spins at the same speed. Just the flat spot. Im thinking AFM or O2 sensor? Please advice needed