2009 Sonata w/i4 Engine & Automatic Transmission problem when using
Problem: The car will not stay in 5th gear with the torque converter
locked up when encountering the slightest incline while the cruise
control is activated. Instead, the car will 5-4 shift, unlock the
converter, go awhile, do a 4-5 shift, then do a 5-4 shift, so on and
so forth. This is an undesired operation of the engine/transmission
ONLY while the cruise control is activated. This has happen on eight
of the 2009 Sonata's I have experimented with.
If the cruise control is OFF and you are just using the gas pedal, the
trans will stay in 5th gear, and the torque converter will stay
locked, on even bigger hills, and you can even accellerate gently
without the transmission doing a downshift. This is the desired
operation of the engine/trans that should also happen when the cruise
control is enabled.
I have asked the dealer to fix this problem so the the cruise control
operation of the transmission/engine will more closely pattern itself
to non-cruise control operation. They say that they cannot because
Hyundai USA has not released a software upgrade to fix the problem
even though the vehicle is a one model year old and the 2010's are
programed the same.
If this is happening to you, find it irritating and fuel inefficient,
and you would like it fixed, I encourage you to inform your dealer and
to call Hyundai USA customer service at 800-633-5151 and make your
wishes known. (Their phone number & address are at http://www.hyundaiusa.com
located under the "about Hyundai Tab" - "Contact us"). I have already
made their engineering dept well aware of this problem.