Hi, I have a 2008 Base TL AT. It shifts as expected, unless I am going at least 50MPH and floor it to pass. The RPMS will go very high before it downshifts. Mechanic calls this "flaring" and says the transmission is on the way out.

However, I have tried both my roommates' cars, a Lexus RX350 (2012) and a Lexus IS350 (2006) and they both do the same thing, to some extent.

The trans doesn't slip under any other circumstance, and is fine in "auto-stick" mode as well.

Is this a normal slushbox thing, or what do y'all think?

Cheers.

 

You should see some RPM increase when you floor it, right before the trans shifts. This is going to be dependent on the torque converter and how 'loose' it is. However, anything past some very minor RPM increase sure sounds like the frictions in the transmission are slipping. Nothing else can cause that unless you're physically accelerating.

This does not sound like typical behavior, so the fact that you say two other cars act similar is a little confusing. Just how many RPM increase are we talking about here?

Auto transmission slip is generally very bad and means imminent failure. It could be something minor and external, or internal and major. Low line pressure would cause it too, which can be caused by all sorts of things. Everyone is probably going to recommend replacing the solenoids that are commonly replaced around these parts, and a transmission drain and fill is a reasonable idea.

 

Can you maybe ask someone to record it while you punch it and post it on youtube? That may help.

 

Thanks! Sometimes when in 5th gear doing over 50 or 60, if I floor it, the rpms will go all the way near redline before shifting. The other 2 cars weren't THAT extreme, maybe 2 or 3K rpm increase before shifting.

I did a 3x3 and there was some improvement but not much. I do have a warranty in effect. Shop says not to go with Honda transmission from Ohio, but from some other company they deal with.

This only happens occasionally, and not with normal use.

 

you got problems and you might want to see what they are. could be a solenoid, internal trans leak or it's gonna die...

 

please don't listen to your tranmission shop UNLESS they have reputable buidling bullet proof trans for racing world.

 

If you're hitting redline in 5th gear before a downshift, and this has been happening for some time, its likely the transmission will fail some time soon. That's quite a bad sign.

The confusing bit here is why you claim two other cars do something similar. 2-3,000 RPM of 'slip' before a downshift is WAY beyond acceptable. A few hundred RPM is all you should see, just a minor blip.

I've noticed these kinds of things happen to well functioning cars in extreme cold, say below 0ºF. Given your location that does not appear to be the issue.