elitegroup

Greetings all! I have been lurking around here since I bought my '99 RX 300 AWD three years ago and have just registered. After I bought it I realized it had much slower acceleration then my other vehicles ('03 Camry V6 SE, 03 Highlander V6 4X4) which share a similar engine. The problem I have is the transmission feels as if its starting out in 2nd gear resulting in a slow acceleration, and have to really press on the gas to keep up with the other cars.
However on the highway it feels just like my other vehicles and has tremendous power and speed.
From a standstill how many shifts should I be able to detect fon a normal rx?

Additional notes: transmission shifts smoothly and the fluid was flushed last year, drivers side front brake caliper may be frozen (as I had a terrible time getting the piston to go back in when I changed the pads and ended up bending 2 large C-clamps , DTC code pulled last year was general misfire ( I cannot remember exactly), the CEL has come back on recently but I haven't pulled the code yet. Any input would be appreciated!

99rx

iTrader: (6)

Well one, you should make sure you aren't in snow mode. Look down next to the shifter and make sure the PWR/ECT/SNW button is on power. And then second, you should get the code read and report back.

hypervish

Welcome to Club Lexus!

I agree with 99RX, make sure it's not in snow mode. There should also be a light on the dashboard that indicates you are in snow mode.

Have you ever changed the transfer case, and rear differential oil? How many miles on the RX? Have you tried driving with "PWR" mode on?

I think the RX300 has more than enough power for it's intended purpose.

elitegroup

I had the front and rear diff fluids changed when I had the trans flushed.
From what I read in the manual the ETC power button has three settings; power, normal, and snow. I drive in "normal" mode (rocker in center position) and when I push it forward to Power , the car shifts at higher rpms and feels as it it has more power than normal. However, it still feels week off the line. I tried pulling the codes with my Innova 3100a but it can't establish a connection regardless of key position. The obd2 port contacts look corroded - I'll try to clean it and try again. The engine starts up no problem and seems normal. This vehicle accelerates like my old 1990 Corolla 3sp auto from standstill but at higher speeds it is fast and peppy.

sktn77a

iTrader: (2)

Do you notice any change when you put it in SNOW mode?

elitegroup

Okay thanks for the input guys... I put it snow mode and the car feels definitely slower than normal and power modes. Snow mode feels like a 2nd gear start. So I guess my assumption that the lack of power in normal mode due to 2nd gear start is incorrect and it is probably working properly. How do you find acceleration compared to other vehicles?

hypervish

I think the acceleration is just fine, nothing spectacular but certainly better than others. You have to remember the RX weighs near 4,000 pounds. That's a lot of weight, also the engine produces max hp at 5,200 rpm. At 3,000 rpm only 94hp is being delivered to the wheels.

The only thing I'm dissatisfied with is the speed limiter at 112, which is there because of the speed rating on the OE tires.

LA4Mead

Yeah, no complaints about power from a standing start or otherwise from me, Early '99 2WD. You should be able to discern 4 distinct shift points under heavy throttle as well as some that are extremely subtle (torque converter lockup) under very light throttle. Have a passenger watch the tach for you.

A theory:
Perhaps what you may be experiencing is from a standing start, under heavy throttle, even very subtle wheel slippage will trigger traction control (if equipped 2WD "TRAC" or stability control) that pulses the brake at the slipping wheel and also reduces engine power to eliminate slippage. The Toyota/Lexus stability and traction controls are intrusive, especially with stock tires that don't grip well, and the result is the feeling that you can't get away from a stop quickly because you are being over-corrected by engine management.
I fixed that by grippier tires. Mine rarely intrudes, unless I tromp on the pedal too quickly, but with $4.50/gallon gas out here, I can't afford to do that!

elitegroup

Hi guys I finally got around to fixing my poor acceleration problem. On Saturday I changed my front brake calipers and that solved the poor acceleration! The power is no longer lacking and acceleration is vastly improved. The bizarre thing is that I didn't even notice any excessive fuel consumption one would expect with a sticking caliper. It turns out the drivers side caliper was frozen and the inner pad was worn down considerably compared to the outer one. I should of changed those calipers a long time ago! It also fixed another issue I was having but forgot to post in my original post...The issue that during the first 2-5 km's of my morning drive the vehicle would not freewheel when I let off the gas, and felt as if the brakes were dragging. I read alot of threads about our transmissions taking a while to warm up on cold mornings and just attributed the problem to that. I recommend anyone experiencing similar issues to check out the brakes first. Now I just have to hunt down why the computer is throwing a po171 code....

hypervish

Awesome to hear it's fixed!

Also, thank you for coming back and posting your solution. It may help someone out in the future.