comotiger

Hi all, my car runs very well 99.9% of the time. However, on occasion, it will struggle to pick up speed after a stop. The car would rev high (~3-4K) before shifting, but soon the car is back to its fine self. I have noticed that the "struggle" seems to happen at the same few locations along my route. When I described this issue to my Lexus SA on Saturday, I expected to hear about some problem with the transmission. Happily, the SA said that everything checked out with the car and that nothing is wrong. However, he did mention something that I did not know, and would like some corroboration here.

He said that our 8 speed transmission engages the first gear very sparingly to avoid ragged/jerky starts from a stop. He said that most often the car will downshift to 2 at a stoplight and start moving again in this gear without going down to 1. According to this theory, the reason for my car "struggling" at a few specific points would be because it had downshifted to 1 for some reason only at these few locations and revving higher than normal (struggling) upon starting to move again.

Is this true or is my Lexus SA smoking something ???

enoch861

Many cars, including the LS with 6+ speed transmissions do actually avoid shifting into first for smoother take offs. Now, I'm not sure why your LS should "struggle" to start per se but rather it should jerk forward due to all that low end torque we have. I've noticed in my A6 and LS if they happen to shift into first while stopping you'll get a little jerk while they shift because of the high engine braking into first. Typically after that they seem to shift out of first and back into 2nd while stopped, at least with the LS. The A6 will momentarily stay in first when you start accelerating and then seamlessly shift into 2nd. But yes, many cars do actively avoid shifting into first in normal driving modes. Sport modes do always engage first gear though.

sktn77a

iTrader: (2)

Lots of cars with multispeed slushboxes start off in 2nd gear as a fuel exonomy measure. Doesn't seem like it would amount to much but an 0.1% improvement in fuel economy over all the cars a manufacturers sell adds up and may help them avoid not meeting CAFE requirements.

Oliver Enterprises

He's smoking something ... which is exactly on par with all or most information obtained from a dealer. Mine has a tendency to go into first more than I would want it to ... but its not horrible about it. For example, if I'm going to do a California Stop, at just the right speed (maybe like 5 mph) it will shift to 1st sometimes. No jerkiness, it just revs more than I would prefer. If it would remain in 2nd, the V8 has enough torque to just grunt and move on out.

I don't know how to state this, but part of my job when working with Hyundai was interfacing with dealerships and their staff. The level of expertise about the actual product at a dealership is FAR REMOVED from what you have at the development centers and the manufacturing locations. Those last 2 locations know intimate details about vehicles, inside and out. Dealerships only know as much as is needed to stick a person in a car, or to have a car leave the service area. Anything else they say, take it with a spoonful of salt. My $0.02.

comotiger

Well, looks like there is general agreement on what our cars do, which is to seldom go into 1st gear. The SA said he discussed with the service techs before offering this answer, so he is alright

LR3vsLS

Mine starts in 1st from what I can see, all the time...im going to check today.