lucyq

I have been trying to wrap my head around my 2008 Lexus LS460’s transmission downshift (or “kick-down”) hesitation for some time. Not only does it hesitate to downshift, after the (eventual) acceleration does occur, when I lift my foot to stop the acceleration, the transmission remains in gear/hesitates to upshift (leaving the engine revving in the lower gear) for an unacceptable time.

Seeing the NHTSA complaints from other owners[1] gives me hope that Lexus has a fix for it. Lexus owners are not the only people who have experienced the same problem. For example, Jay Shoemaker, in his November 13, 2006 article on the Lexus LS460 (titled “Lexus LS 460 Review”), described the delay in downshift as follows: “there's an unacceptable hesitation as the transmission rows through a few gear changes before finding the meaty part of the engine’s torque range” (http://www.thetruthaboutcars.com/2006/11/lexus-ls-460/ ). My take on this “unacceptable hesitation” is it reflects a software programming issue.

Regardless of the number of gears a transmission has, a rapid depression of the accelerator pedal by a given distance (of pedal travel) should cause the computer to rapidly select a gear to downshift to and make it happen quickly (based on the computer program that takes into account the rate of pedal depression, the distance of pedal travel, and the speed of the car). The transmission should downshift to that selected gear almost instantaneously given today’s fast computers, regardless of the power created by the engine (i.e., regardless of what the variable valve timing (VVT) and direct injection (DI) programs are doing).

Has anyone else experienced this downshift hesitation issue? Is there a Lexus Technician out there who can explain why this occurs and how it can be solved? Is there a Service Bulletin with an official fix?

------------------------------------------------
[1] “THE CAR WILL (INTERMITTENTLY) HESITATE TO ACCELERATE. THIS IS ESPECIALLY DANGEROUS WHEN YOU ARE TRYING TO MERGE INTO THE FREEWAY OR SIMILAR OCCASIONS. WHEN ATTEMPTED TO DEPRESS THE GAS PEDAL WITH EXPECTATION THAT THE CAR WILL RESPOND AND ACCELERATE AS NORMAL, THE ENGINE JUST REVS UP AND THE VEHICLE DOESN'T MOVE ANY FASTER THAN CURRENT SPEED. THIS WILL CONTINUE FOR 5-10 SECONDS THEN IT KICKS IN. THIS DELAYS IS VERY DANGEROUS WHEN YOU WANT TO GET OUT OF HARMS WAY (ACCELERATE TO MERGE INTO FREEWAY, PASSING ETC). THE PROBLEM IS INTERMITTENT AND WILL GO AWAY BY ITSELF WITHIN A FEW HUNDRED MILES (BUT WILL COME BACK SPORADICALLY). ALL THIS HAPPENS BY ITSELF AND CANNOT BE REPRODUCE AT WILL” (NHTSA ID Number: 10507520, Date Complaint Filed: 04/08/2013).
“WHEN I NEEDED TO PASS A VEHICLE, I WOULD STEP ON THE GAS (MOST OF THE TIME PUSHING THE ACCELERATOR PEDAL TO THE FLOOR) THE CAR WAS VERY SLUGGISH AND UNRESPONSIVE. IT WOULD TAKE ABOUT 10 SECONDS FOR THE VEHICLE TO SLOWLY ACCELERATE AND THEN THE CAR WOULD TAKE OFF WITH THE RPMS CLIMBING NEAR RED LINE UNTIL I RELEASED MY FOOT OFF THE ACCELERATOR” (NHTSA ID Number: 10506001, Date Complaint Filed: 04/11/2013).
“I HAVE 30,000 MILES LEXUS 460 - VEHICLE DOES NOT ALWAYS ACCELERATE PROPERLY. LOSES POWER AND WILL NOT KICK UP FOR A FEW SECONDS UNTIL FINALLY KICK UP. THIS HAS HAPPENED AT LEAST 5 TIMES IN 3 MONTHS. NOT SAFE WHEN YOU COUNT ON THE CAR TO SPEED UP TO GET INTO THE FREEWAY OR INTO A STREET WITH TRAFFIC” (NHTSA ID Number: 10392877, Date Complaint Filed: 03/25/2011).

Tee

This has been discussed several times over the years, here is the link found in the FAQ sticky located at the top of the LS460 forum.

https://www.clublexus.com/forums/ls4...-problems.html

Nospinzone

Yes, the situation has been very well documented on this forum.