I have an 06 5.7 hemi with a 545RFE tranny. It is very sluggish to kickdown when I depress the accelerator. When I depress enough to kick it in it kicks down too far, neck snapping. Anyone know where to start diagnosing? Is it vacuum operated?
The 545RFE is a fully electronic control transmission. There are no vacuum lines on this transmission.
If you are experiencing issues with downshifts, can you take a video and post it? The easy way is to shoot a video and upload it to YouTube and then post the link here.
How many miles have you put on the truck since you bought it?
Have you serviced the transmission?
What does the fluid look like and smell like?
Is the check engine light on? Either way hit up the local auto parts store to connect a scan tool so you can see if there are any
1-Trip Failures stored or even a stored DTC.
Now, with that being said, how about some background on the truck. Is this the stock, original 15 year old transmission?
How far are you having to press the accelerator pedal to get the transmission to downshift? If you are cruising the highway in 5th gear it can take quite a bit of pedal input to get it to downshift from 5th to 3rd or even 2nd Prime. The 5-4 downshift should occur pretty easily because it only takes a few degrees of TPS input to downshift. The 5-3 downshift requires quite a bit of pedal because the software in the PCM/TCM is designed to keep the trans in high gear or the highest gear available based on engine load and throttle input for fuel economy and emissions purposes.
The 5-2 downshift is really rough on the RFE transmissions and I don't recommend trying to get it to downshift that far to accelerate to pass someone. Here is what I do. I tap the Tow/Haul button while cruising. When I do it will downshift from 5th to 3rd and engage the converter clutch. In Tow/Haul Mode 5th gear is locked out and the trans will only upshift to 4th gear. If you press the button again it will say O/D Off and the trans will only upshift to 3rd gear and engage the converter clutch with 4th and 5th being locked out.
This is the way I always recommend to downshift to a lower gear while driving, especially once you are in 5th gear.
The only real way to diagnose a concern like this is with a scan tool connected and driving the truck which only shops or mechanics like me can do. There may not be anything wrong with your transmission though.
I Think some further diagnostics is required with a scan tool and a mechanic who knows what they are looking at in the scan tool to determine if there is really a problem or not.