Hello friends, hope somebody can explain something to me. When I'm cruising in 5th gear (in auto mode) and start stepping easily on the gas there will suddenly be a quick increase in RPM, as if it had down-shifted but is still in 5th gear... why is that? Tranny is not slipping. This is nothing wrong, I just want to understand what is going on in power plant / trannsmission. This is happenning probabbly between 2K and 3K RPM. Can there ba a ratio change once a gear is engaged? Maybe ignition timing or valve operation switches between a certain range? I am curious - not trying to solve any problem.

 

TQ converter lockup. It locks when cruising & allows the RPM to raise slightly when you step on the gas before it dis-engages.
http://en.wikipedia.org/wiki/Torque_converter

 

Tanx Fuzzy, learned a lot today about the TQ (very interesting, I had slight idea of how it worked but now it is all clear).