Recently I purchased an X308 3.2 with 140k miles on the odometer. The car is dealer maintained by the previous owner and overall in a very good condition. The only issue is that it seems to lack power, it's much slower than my previous 3.2 X300. With full throttle the car accelerates slowly until 4k rpm, at higher rpm it's much faster. Almost feels like the turbo kicks in around 4k rpm.

The engine has no error codes and I have replace the air mass sensor. This made no difference unfortunately.

Any ideas what could be causing this?

 

Check that the throttle cable does not need adjusting. Do a search for instructions.

 

Thanks. There was quite a bit slack and the throttle feels a bit more responsive. I feel this may have been part of the solution but I'm not there yet. There's still this boost at 4k RPM.

Or is this normal behavior for the AJ-V8 engine? I expected a more linear curve with more torque in the 1500-3500 rpm region.

 

The feel that the 3.2l V8 is a little slower than the 3.2l I6 is right. I had a 3.2l I6 before the V8... It felt more powerful in normal driving. No wonder: long stroke, "huge" cylinders (more than 0.5l displacement/cylinder vs. 0.4l/cylinder) and that causes more torque at lower RPM. The boost at 4000 RPM is normal. That is the advantage of a more sophisticated multivalve intake. At higher RPM the intake manifold works wonders.

BUT when you rev the hell out of the V8, it'll shift faster and better than the I6. So what you are feeling is the standard V8.

So as said, your car is totally normal. If it doesn't feel like you're kicked in your neck at around 4000 RPM, then something is wrong.

 

Thanks for the reassuring words. I've driven more miles that last couple of days and can feel it's definitely faster now. And with the correct tension on the cable the engine performs better at low revs too.