I will be travelling at say 120km/h or ~ 80MPH and if I hit the brakes every so slightly because a car in front of me is say slowing down to 110km/h, my tranny shifts down and the RPM's shoot up from approximately 2,700RPM to 3,400RPM. It's very noticeable. I have an automatic transmission.

Interestingly enough, I had the computer reset and the ECU reprogrammed a few weeks back which corrected the issue, but it's back again. Anyone have any suggestions? It's causing for a very wacky ride as it relates to the RPMs.

No mods on the car - everything is completely stock. Any ideas/suggestions?

 

Maybe youre experiencing the downshift rev-matching, which is normal when slowing down.... but cant say for sure with your description

 

Are you in D or DS? Sounds like engine braking

 

Rev matching..

 

Yeah, it's actually a feature of the car. Driving in DS will make it more sensitive than in D.

 

Its just your torque converter lock-up.

When shifting into DS mode it engages the 4th gear lock up. That is causing your rpm jump.

Pretty cute isn't it? All six of my gears lock up too. It's called disengaging the clutch.

 

I do not have the car in any DS mode when this occurs. I'm using the regular DRIVE position. If this is a feature where the engine is used to brake or slow down, then I find it's engaging far too quickly. I'm talking the slightest braking at high speeds leads to high RPM. Weird.

 

Maybe it's worth checking with your dealer. It sounds like it is a bit over reactive if it's doing it in D. The increase in rpms is just because the transmission is downshifting, but a tap on the brakes at freeway speeds shouldn't force a downshift. Maybe the ECU reprogram didn't take and it's just relearning old bad habits.

 

What you are describing seems to be normal when driving in D mode. I double checked when I first noticed this. When running along backroads, I tap the brake just to the point of feeling the calipers grab. If done quick enough, the car will downshift one gear and be ready in advance for me to power through the turn. It will then shift up as I ease up on the throttle. This is different from torque converter lockup. If you want to know what it feels like to have the torque conveter unlock, place the shifter in DS and use it to shift up as you accelerate. Then try to lug the engine and you will feel the rpms go up a bit as you slow down (going uphill in 3rd or 4th without downshifting for example). All this will happen before the tranny downshifts as the tranny is smart enough to prevent actual engine lugging.
As far as having the tranny shift differently after resetting the ECU, keep in mind that the computer actually learns the way you drive and changes the shifting characteristics accordingly. This takes time and may not be immediately evident after an ECU reset.

 

I thought I had read somewhere that the car learns your driving style. Maybe if you brake on the highway, it's usually followed by some gas? I'm not sure if the learning algorithm is that sophisticated, but it might be.