Good afternoon. I have had a problem with my Volvo S80 T6, 1999, which is as follows: when I am accelerating, up to 4500 rpm the car is very slow, and from there accelerates well. The codes I have in obdII are 1237 and 0014. I already changed the TCV and the timing belt is synchronized correctly. But the car remains the same, with weak and hesitant acceleration. Anyone who can give me a hint of what it might be, I appreciate it.

 

I read an older post which suggests the P1237 is a generic code but some tables map to an ECM-6806 code which points to an incorrect boost pressure level (typically the TCV) so you need to look for other issues like an air leak etc. As to the P0014, that's saying your cam timing is advanced. This can be caused by the VVT solenoid not working properly or more likely, the VVT gear's belt timing is one notch off.