I have an 07 AWD with 10k and I have been experiencing something kind of strange.

When approaching to a stop or slowdown, before the car stops the tach needle drops to about 600 RPM then bounces back up to about 1100 RMP then it gradually goes down to 550-600 RMP when the car stops completely. Once in a while (at least I felt 3 times and my wife felt many more times), when the car just stops, you will feel it shaking, seems like the car is shutting down and it only happens about 1/10 second. This feels exactly like when you turn off your car and right before it is off, you turn on the key to position II and the car is up running again.

Please tell me if this is normal before I have to take it in.

Thanks fellas.

 

It is possible that you have a bad EGR valve that is opening up and closing at the wrong time. The sad thing, it may not store a code in the PBD II because the car is not dying out. The computer is correcting this. The only way to diagnose this issue to it have a tech plug in a scan tool into the OBD II port while driving it in order to recreate the issue. If the issue occurs, the tech can shut down the car and obtain the code. This is my take on this. I have seen this happen with other makes and models and is a bit frustrating. Some dealers have even replaced fuel pumps unnecessarily due to this.

 

are u braking when the rpm jumps? it could be brake assist. it happens to me when i'm going downhill and brake, the car would downshift automatically...

 

Yes, of course it happens when I brake. Like I said, it happens when I slowdown ( like 10 mph) and before stop completely.

Thank you all for your replies.

 

That isn't brake assist. Brake assist only kicks in during panic stops, where it uses the ABS hardware to increase braking pressure to the limit of traction.

What you and the original poster are noticing is the car downshifting during normal braking, which seems to be a feature of this transmission.

 

this happens to me also. a few times, maybe once or twice a week, when i'm braking and almost to a stop, it feels like the engine is about to die (vibrations and all that), and my car starts to feel like i'm driving on a washboard road. strangely enough, i don't notice my rpm needle dropping below the 600ish mark when this happens.

 

do you mean when the transmission downshifts?

 

at that point, given the speed i was going, and the fact that i was braking normally and just 1-2 seconds from a complete stop, wouldn't the torque converter already be disengaged? or does it only disengage when the car comes to a complete stop?

 

it happens to me too but mine is not an AWD....but my torque shoots up a little when i am going to a full stop...

 

Well, first off, our cars dont have EGR. Lexus hasnt used EGR for years, it uses VVT-i to gain the same effect. It sounds like your car is downshifting normally. My car does the same thing. Are you in ECT mode or not? I seem to notice it a lot more in ECT mode. As far as the car coming close to dying, i would bring it to a dealer and have them inspect for pending codes. There may be something going on in there, and it doesnt necessarily have to set a check engine light.

 

If no EGR, then it is possible that the OP has a faulty Exhaust Gas Sensor. The 2Gen's have one. I have not taken apart ths engine yet, so My knowledge on the 2.5 and 3.5 is limited. I just try to help trouble shoot based on what I have seen in the past. It is often hard to diagnose without having a respective OBD II trouble code to refferance.

 

nothing wrong with the engine. That's normal downshifting.

 

This is exactly what happened. My tach needle does drop down to between 500-600 RPM. So I guess once in a while when I feel like the car is almost dying is when the RPM drop below the 500 mark but it immediately bounces up to the idle range?

So I guess it's normal. I know that I'll somewhat get the answers from here. Thank you all.

 

I did not see this thread before posting. But I posted a very similar thread under "Erratic tach" subject. I have the exact same symptom as GoHuskers. As I am approaching a traffic light and slowing down, the tach bounce back and forth almost 300-400 rpm. This bouncing happens during downshifting of gear and most notable if the gear downshifts rapidly from 4 to 2 (skipping 3). I have been meaning to do a video clip on it. If I do, I will post it.