Larry96815

Update: I had my '05 RX 330 ecu update done today. I have only driven about 15 miles since but it really seemed (so far) to help. I tried to get it to hesitate and it would not do it. Wish me luck, but in my case it seems to be helping. Further update after a few more miles.

Aloha,
Larry

Larry96815

Another 1 hour city drive today and all is great. I really think the update helped.

Aloha,
Larry

yaro1

I think I had a similar problem on my RX330 where the car would feel laggy for the first second when I depressed the throttle. The car felt awkward and laggy. However, I had a feeling the ECU had learned my driving personality wrongly so I had the ECU reset. After the reset, the RX felt much quicker than before (the power came quicker). Maybe a simple ECU reset will fix the issue for some?

Foster 525

CK 6SPEED is correct with regards to his post!
I got my vehicle back yesterday, and the service advisor said since it is a 2007 model, there are no TSB updates on the programming on the ECU available for my vehicle. So the symptoms remain, but are at least liveable.

If there is any consolation, I had a 07 ES350 sedan for a loaner (nice, car) which had 700 miles on it and the hesitation/throttle lag issue was still apparent, but not as pronounced. I spoke to a technician who agreed with me about the hesitation/throttle lag issue, and mentioned this is an inherent symptom of this 3.5 liter engine.

Here is the ALLDATA for all TSB's: http://www.alldata.com/tsb/

Larry96815

Okay, it has been one week now since the ECU update. So far all I can say is WOW! In my RX it made a BIG difference. So much more repsonsive, no more waiting for the shift or wondering what it is going to do next.

Aloha,
Larry

jerrsRX350

There is endless information on the Edmunds Avalon forum for simular lag (hesitation) problems. Seems to be less of a problem in the RX 350 than on my 2005 Avalon??? It is only a minor problem for me in either case but seemed to be very aggravating to other owners of Avalons (3.5).

Domer330

i have the 330 as well, and it lags in lower speeds. My vehicle goes in next week and i don't think there is going to be a cure for this problem.

Larry96815

It really helped on mine, good luck.

Aloha,
Larry

willard

If you browse about your will find owner complaints of throttle lag or engine delay/hesitation for Ford, VW, Toyota, Lexus and others, all concerning vehicles with automatic transmissions and mostly FWD or front biased AWD vehicles.

It is my firm belief that sometime in the mid to late ninties someone, or some group, with TONS of clout over the automtive industry issued an edict that the safety of FWD and front torque biased AWD had to be brought into line with their RWD and rear torque biased AWD brotheren.

My vote goes to the automotive insurance industry. Accident statistics most readily available, certainly with the CLOUT and enough synergy with the industry to want to keep this on the QT.

The safety issue involved the potential for loss of directional control due to engine braking, especially FRONT engine braking, in wintertime adverse roadbed conditions. There is also the issue of the potential for engine braking to interfere with ABS, again especially detrimental for FWD vehicles.

So, late in the last century the shift pattern/schedule was revised across the industry to address the safety issue. The new shift pattern dictated that anytime there was a FULL lift-throttle action by the driver the transaxle would be quickly upshifted so as to prevent any significant level of engine braking.

The problem that quickly arose from this change was that if the driver quickly returned to acceleration "mode" the engine was now at idle and the just previously commended upshift would deplete the ATF pressure/flow reserve. With little or no ATF pressure/flow available the subsequent downshift due to the driver's re-application of pressure to the gas pedal could not be quickly completed.

As evidence of Lexus has now replaced a LOT of early RX300 transaxles.

By 2001 Lexus had figured out the problem and increased the displacement of the ATF oil pump, gear type oil pump, to provide more pressure/flow at engine idle.

So, the 2001 RX300's, even with all equipped with the extra ATF cooling via the tow package, OVERHEATS the ATF to the point that the recommended traansaxle ATF service interval has declined from infinity (the life of the vehicle actually) to every 15,000 miles.

What to do, what to do...??

Oh, I know, let's use DBW, e-throttle, to delay the onset of engine torque until the subsequent downshift can be completed, the clutches firmly seated.

So the RX330 used the old standard ATF gear pump displacement but was equipped with DBW "to protect the drive train".

Regretably some one else in engineering had already decided that the VC, Viscous Clutch, in the AWD version was contributing to the overheating of the ATF and so it was removed, not to return until the advent of the RX350.

Is Lexus listening, do you suppose?

The final FIX...

SNOW mode...Assuming the new shift pattern upshift technique is to help alleviate accidents due to loss of directional control arising for engine braking, why not just have a SNOW mode that can be activated by the driver, by a rain sensor, or if the OAT hovers around or below freezing?

Upon a full lift-throttle event in SNOW mode the transaxle would remain in the same gear ratio (ready to SURGE forward on command) but the engine RPM, via DBW, would not be allowed to fall enough to provide a significant level of engine braking to the driven wheels, FRONT, rear, or ALL.

Absent being in SNOW mode the shift pattern could be the same as it was pre-2000, NO upshifting on full lift-throttle events.

No HIGH potential for engine braking, FRONT especially, to put your life at risk or interfere with ABS if the roadbed traction is satisfactory.

I guess on second thought ABS interference via engine braking might still be an issue. But that could addressed by keeping the upshift pattern but delaying it until the brakes are applied.