Hey... Just bought a maxda mx6 which get a sudden boost of power at 4000 rpm
I'm guesing that this isn't supose to happen... Does anyobe know what could be wrong?
It's a 2.5 v6 from 1992

 

That sudden boost my friend is perfectly normal, Similar concept to a vtech in a honda or as what most call the power band in your car it is called the VRIS, and thats it kicking in. it is intended for a torque boost for sudden need for power. The KL series was my favorite for this specific reason.

 

My 2006 does the same thing, power really comes on @ 4000 rpm, mine is Variable Valve timing thing. It's a good thing--Zoom Zoom!

 

I have mine set to kick in at 2800 rpm on the ecu. for the 90's k series the boost comes from two additional butterflies within the intake to increase air flow, thats what the extra tube in the back is for and the little kink on the left right over the belts. a little different but same results as auto adjusting valve timing.