Originally Posted by
DmaxMaverick
This does not indicate transmission slippage, in any way. In fact, it may eliminate that possibility, entirely. The RPM increase I/we referred to was before a downshift, holding the same gear. What you describe (except for the loss of power), sounds like completely normal behavior.
Do this, under the same conditions you would expect to experience the problem:
Accelerate normally (T/H OFF) up to about 65 MPH and set the cruise control. You should be sitting on about 1700 RPM's (maximum available torque at low input shaft speed). Now, floor it, and watch the tach and speedo. You'll have about 4-5 seconds before a downshift, so let off before that. Repeat as necessary to provide the longest WOT condition, before a downshift is forced. The RPM's should not increase any more than necessary to increase the ground speed. If it does, these conditions will indicate any slippage. If you just accelerate, the transmission is normal. If it's slipping, you will see the tach increase at a greater rate. When you let off (zero throttle), if it's slipping, you will see an immediate drop of RPM's (before it matches ground speed). If the RPM's and ground speed remain synchronized, NO slippage.
If it downshifts immediately when you floor it (cruise control engaged), you are missing an important PCM/TCM calibration update, or something else is wrong. DTC's, even in history or pending (no SES lamp), can force performance issues and low power. If the TCM has a fault, it WILL command the MIL/SES (P0700+). If the cruise control doesn't work, it may indicate this, as well.
Another thing you can/should do is, take your VIN to your dealership and have them check for your latest calibration update, and see if there is a later update. They should do this part free. If an update is available, have them install it. This takes less than 1/2 hour, and they should charge no more than that. There is no charge for the calibration, only the labor to install it.