07 Rx 350 Awd, Surging

[jednav]

Just got back from the dealership. Basically, they say it is the nature of beast. So, either you live with it or push it off the cliff.

I rode with the techie when he test drove the RX. He felt all the things I took issue of, and I gave him the TSB number from the other thread.

He looked it up and he said it was just some programming notes that doesn't apply to my RX, and for sure not the "FIX" I was hoping for.

As a consolation, he further said the LEXUS is good in recognizing customers concern and may come up with a solution to issues raised. He pointed out some issues on other models that was taken cared of.

Also, he assured me that these vehicles were engineered this way viz-a-vis a bunch of factors, with gas consumption as one of them. However, not all customers are happy with its drivablity conditions.

The techie also encourages everyone to raise this issue/s on their next visit to the dealership. In other words, make a lot of noise to be recognized.

[wwest]

Just got back from the dealership. Basically, they say it is the nature of beast. So, either you live with it or push it off the cliff.

I rode with the techie when he test drove the RX. He felt all the things I took issue of, and I gave him the TSB number from the other thread.

He looked it up and he said it was just some programming notes that doesn't apply to my RX, and for sure not the "FIX" I was hoping for.

As a consolation, he further said the LEXUS is good in recognizing customers concern and may come up with a solution to issues raised. He pointed out some issues on other models that was taken cared of.

Also, he assured me that these vehicles were engineered this way viz-a-vis a bunch of factors, with gas consumption as one of them. However, not all customers are happy with its drivablity conditions.

The techie also encourages everyone to raise this issue/s on their next visit to the dealership. In other words, make a lot of noise to be recognized.

By "surging" do you by any chance mean a fairly slight feeling of "freeing up" of forward rolling resistance?

These cars will upshift the transaxle during full lift throttle coastdown events at ~40-30MPH and at ~10-5MPH brake on or not. A "slingshot effect" feeling at the higher speed and a feeling of being bumped slightly from behind as you slow toward a full stop.

[jednav]

Just got back from the dealership. Basically, they say it is the nature of beast. So, either you live with it or push it off the cliff.

I rode with the techie when he test drove the RX. He felt all the things I took issue of, and I gave him the TSB number from the other thread.

He looked it up and he said it was just some programming notes that doesn't apply to my RX, and for sure not the "FIX" I was hoping for.

As a consolation, he further said the LEXUS is good in recognizing customers concern and may come up with a solution to issues raised. He pointed out some issues on other models that was taken cared of.

Also, he assured me that these vehicles were engineered this way viz-a-vis a bunch of factors, with gas consumption as one of them. However, not all customers are happy with its drivablity conditions.

The techie also encourages everyone to raise this issue/s on their next visit to the dealership. In other words, make a lot of noise to be recognized.

By "surging" do you by any chance mean a fairly slight feeling of "freeing up" of forward rolling resistance?

These cars will upshift the transaxle during full lift throttle coastdown events at ~40-30MPH and at ~10-5MPH brake on or not. A "slingshot effect" feeling at the higher speed and a feeling of being bumped slightly from behind as you slow toward a full stop.

Yes. This is a safety issue. Wondered why was this not cited in all the car reviews.

[wwest]

Just got back from the dealership. Basically, they say it is the nature of beast. So, either you live with it or push it off the cliff.

I rode with the techie when he test drove the RX. He felt all the things I took issue of, and I gave him the TSB number from the other thread.

He looked it up and he said it was just some programming notes that doesn't apply to my RX, and for sure not the "FIX" I was hoping for.

As a consolation, he further said the LEXUS is good in recognizing customers concern and may come up with a solution to issues raised. He pointed out some issues on other models that was taken cared of.

Also, he assured me that these vehicles were engineered this way viz-a-vis a bunch of factors, with gas consumption as one of them. However, not all customers are happy with its drivablity conditions.

The techie also encourages everyone to raise this issue/s on their next visit to the dealership. In other words, make a lot of noise to be recognized.

By "surging" do you by any chance mean a fairly slight feeling of "freeing up" of forward rolling resistance?

These cars will upshift the transaxle during full lift throttle coastdown events at ~40-30MPH and at ~10-5MPH brake on or not. A "slingshot effect" feeling at the higher speed and a feeling of being bumped slightly from behind as you slow toward a full stop.

Yes. This is a safety issue. Wondered why was this not cited in all the car reviews.

"...This is a safety issue...."

Actually, no, this is a fix for what was a safety issue.

But first, why do you think it a safety issue?

I first noticed this "symptom" in my 2000 AWD RX300 and it also exists in my 2001 AWD RX300. After 60,000 miles in the 2001 I rarely even notice these upshifts unless I focus on the issue and pay pretty close attention during coastdown times. When I first noticed it in my 2000 RX I asttributed it to the need to alleviate or reduce the potential hazard of engine compression braking on a FWD vehicle should the roadbed happen to be slippery, ice, packed snow, etc.

It is currently my personal opinion that Toyota adopted this transaxle upshift procedure at the onset of RX production and that is what lead to the premature transaxle failures for those early, 99-00, model years.

By 2001 they had overcome the premature failures by increasing the pumping capacity of the ATF gear type oil pump but then that lead to other problems, primarily overheating of the ATF due to that fixed pumping over capacity with the engine above idle.

In 2004 they went to DBW, e-throttle, to delay the onset of engine torque until the required "downshift" could be completed. The "downshift" immediately succeeding the upshift if the driver happened to go from a full lift-throttle state to a need to accelerate.

Insofar as I can learn the 2-3 second downshift delay still exhibits in some of the 2007 Toyota/Lexus models. And that is a REAL safety issue IMMHO..!

[jednav]

Not a safety issue? I hope you would know what to do when you suddenly need to stop while your truck is skidding all over.

Your historical data doesn't mean much if confronted with such a situation.

I'd rather have an under performing vehicle with good braking power.

[wwest]

Not a safety issue? I hope you would know what to do when you suddenly need to stop while your truck is skidding all over.

Your historical data doesn't mean much if confronted with such a situation.

I'd rather have an under performing vehicle with good braking power.

I'm lost...

I understood that we were discussing the issue of the slight, SLIGHT, surge forward one feels in some of the Toyota/Lexus FWD or front torque biased AWD vehicles upon a FULL lift-throttle coastdown event. It was your position, or so I thought, that this slight surge represented a serious safety issue and I said I thought not.

I'm clearly of a misunderstanding somehow, where did I go wrong?

[jednav]

Not a safety issue? I hope you would know what to do when you suddenly need to stop while your truck is skidding all over.

Your historical data doesn't mean much if confronted with such a situation.

I'd rather have an under performing vehicle with good braking power.

I'm lost...

I understood that we were discussing the issue of the slight, SLIGHT, surge forward one feels in some of the Toyota/Lexus FWD or front torque biased AWD vehicles upon a FULL lift-throttle coastdown event. It was your position, or so I thought, that this slight surge represented a serious safety issue and I said I thought not.

I'm clearly of a misunderstanding somehow, where did I go wrong?

Sorry about the misunderstanding, and let me backtrack a bit.

Whenever I let go of the gas pedal from a cruising speed above 75 kmh, my RX normally slows down but as it downshifts to 1st gear, it surges or pushes forward before it further slows down. This is what I will call its downshift cycle.

Now, even if you apply your brakes in the middle of this cycle, the vehicle will carry on to finish the cycle but of course the driver will be caught off guard to the forward movement of the vehicle and hence, will again re-apply the brakes.

The safety issue is not the RX ability to stop but rather the strain on the driver to stop the vehicle at varying road conditions.

Downshifts in auto tranny are there to slowdown vehicle motion, as in engine braking.

Yes, my RX does that too but it surges before it finally settles down.

The techies at my local dealership are aware of this problem on earlier RXs and are now learning and hearing about it on the 07s. Apparently, there is already a computer patch to fix this problem but they are still awaiting word if the same patch will apply to the 07s.

Now, if only I can schedule my emergency braking after it surges, everything will be dandy.

Cheers!

[wwest]

Not a safety issue? I hope you would know what to do when you suddenly need to stop while your truck is skidding all over.

Your historical data doesn't mean much if confronted with such a situation.

I'd rather have an under performing vehicle with good braking power.

I'm lost...

I understood that we were discussing the issue of the slight, SLIGHT, surge forward one feels in some of the Toyota/Lexus FWD or front torque biased AWD vehicles upon a FULL lift-throttle coastdown event. It was your position, or so I thought, that this slight surge represented a serious safety issue and I said I thought not.

I'm clearly of a misunderstanding somehow, where did I go wrong?

Sorry about the misunderstanding, and let me backtrack a bit.

Whenever I let go of the gas pedal from a cruising speed above 75 kmh, my RX normally slows down but as it downshifts to 1st gear, it surges or pushes forward before it further slows down. This is what I will call its downshift cycle.

Now, even if you apply your brakes in the middle of this cycle, the vehicle will carry on to finish the cycle but of course the driver will be caught off guard to the forward movement of the vehicle and hence, will again re-apply the brakes.

The safety issue is not the RX ability to stop but rather the strain on the driver to stop the vehicle at varying road conditions.

Downshifts in auto tranny are there to slowdown vehicle motion, as in engine braking.

Yes, my RX does that too but it surges before it finally settles down.

The techies at my local dealership are aware of this problem on earlier RXs and are now learning and hearing about it on the 07s. Apparently, there is already a computer patch to fix this problem but they are still awaiting word if the same patch will apply to the 07s.

Now, if only I can schedule my emergency braking after it surges, everything will be dandy.

Cheers!

I'm not aware of any modern day FWD vehicle with automatic transaxle that will downshift of itself, I'm very surprised that your '07 does. Coasting down from 75 kmh at what speed does it shift down into 1st, and how does it act during the intermediate downshifts, 3rd, 2nd, etc.

I'm not sure if this will be of any help but I have heard that the new Suzuki SX4 will rev-match the engine speed to road speed if you lift the gas pedal but don't disengage the clutch, presumably also to alleviate the potential dangers of engine compression braking on the front wheels.

Maybe that's what your '07 is doing? Rev-matching and then declining revs on downshifts to prevent a sudden increase in engine compression braking with the downshift?

[jednav]

[

I'm not aware of any modern day FWD vehicle with automatic transaxle that will downshift of itself, I'm very surprised that your '07 does. Coasting down from 75 kmh at what speed does it shift down into 1st, and how does it act during the intermediate downshifts, 3rd, 2nd, etc.

Of course, all vehicles RWD/FWD with auto tranny downshifts by itself. Upshifts or downshifts are determined in relation to speed. Basic principle of auto tranny.

NO, my RX doesn't go from 75kmh to 1st gear immediately. It goes though its natural cycle of downshifting and as it further engage to 1st it will surge or push forward.

[nowstime]

So is this problem something I can take to my local Lexus dealer to get fixed? Or is it just the way it is.

Best,

Jack

[jednav]

So is this problem something I can take to my local Lexus dealer to get fixed? Or is it just the way it is.

Best,

Jack

I think this is something to be taken up with your dealer. And, please post your findings.

I have taken the initiative to run this thread in the hope of creating customer awareness

of this safety issue and for lexus to come up with the right answer.