For the ultimate shifting performance Acura has a few different dual-clutch transmission (DCT) options. But only the 8-speed variant offered in the 1st generation ILX and TLX has a torque converter for managing low-speed accelerations.
It's also the only variant with a transmission shudder that feels like it's constantly slipping.
What is a Dual-Clutch Transmission? ∞
DCTs offer smoother and faster gear changes by using sensors to ask a second clutch to prepare the next anticipated gear ratio. This allows for near instant engagement with a negligible loss in overall torque during acceleration.
Unsurprisingly, they are very popular with performance-minded drivers.
DCTs are often a bit slushy at low speeds, but Acura paired their 8-speed DCT with a torque converter to offer buttery smooth acceleration at all speeds.
Common Complaints About Acura's 8-Speed DCT ∞
Adding a torque converter was smart because it addressed common complaints about DCTs in the first couple gears. But the torque converter Acura chose is a bit heavy in the complaints department and it appears to be dragging the DCT down with it.
Bye-bye smooth shifting ∞
For instance, you can just throw all the shifting advantages you get with a DCT out the window. The torque converter is shifty when cold, and it jerks its way through the gears up to 45mph or so.
The 30-45mph range is a particular nightmare according to many owners. It's been compared to driving over rumble strips and can sometimes result in a "D4" or "Check Engine" light beginning to blink.
Many MDX owners have reported a shudder or vibration when driving at speeds ranging from 35 to 45 MPH. Technicians have attributed this issue to a failed automatic transmission torque converter. A torque converter is responsible for managing the amount of fluid that is passed to the automatic transmission. This is also the device that allows your engine to continue running even when you are at a complete stop. A malfunction of this device can cause your car to display a number of erratic behaviors to include slipping and shuddering.
DCT Slips Into Neutral While Driving ∞
Engine codes P0700 and P0780 mean the transmission is slipping and the only shifting it might be able to successfully accomplish is shifting itself into a fail-safe mode. Sometimes the car will even shut itself off when it comes to a stop due to a faulty shift solenoid or dirty transmission fluid.
On April 23, 2015 Acura released TSB #15-021 titled Transmission Slips or Shifts Hard When Cold covering a specific VIN range of the 2015 Acura TLX.
Acura outlines that the 8-speed dual clutch transmission (DCT) slips on the 1st of 2nd upshift while accelerating. It also acknowledges that the owner might feel a bump or jerk when the vehicle comes to a stop.
The automaker blames the problem on the powertrain control module (PCM) settings, along with the clutches in the torque converter not being properly "broken in." To fix it, mechanics are advised to do a PCM software update, followed by clutch break-in procedure (twice).
Won't Shift Into Higher Gears ∞
Codes P0740 or P0780 might pop up if the vehicle won't shift into its top gear on the highway, or it misfires or dies when coming to a stop. It's usually indicative of a defective torque converter lockup solenoid or converter clutch.
A Series of Recalls for 2015 TLX Owners ∞
There have been a couple recalls for transmission-related problems in the 2015 TLX. But neither seems to have solved the problems owners are having.
Transmission May Not Shift Into Park ∞
On January 30th, 2015, Acura issued a recall (NHTSA ID #14V779000) for 9,392 TLX sedans.
The affected cars were built between July 14, 2014 to November 12, 2014 (V6 2WD), and August 26, 2014 to November 10, 2014 (V6 SH-AWD).
The automatic transmission parking pawl may become contaminated or the park rod may become dislodged or broken. This may prevent the transmission from shifting into the Park position.
If the shift indicator displays "Park" but the park lock does not engage, the vehicle may roll away increasing the risk of a crash.
Transmission Shifts To Neutral Unexpectedly ∞
On January 13th, 2017, Acura issued a recall (NHTSA ID #16V640000) of a 8,354 TLX sedans.
The automaker acknowledged the transmission's wire harness connections may have insufficient crimps, and, as a result, the transmission may unexpectedly shift to neutral.
Image of TLX from this post on CarComplaints.com.