I intermittently loose power in my 2002 SC430 when driving at a constant speed between 10 and 65 MPH. You can feel the car slow down and the RPM drops 200 to 300 RPM. It is necessary for me to depress the accelerator pedal almost fully to restore RPM and speed. The dealer, as usual, tells me they cannot detect the problem (favorite mantra: cannot experience, cannot fix). My wife and daughter experience the problem. My automotive engineer neighbor experienced the problem when I lent him the car for a day. He returned it telling me that I had a drive train issue. Finally I took it to a reputable independent service facility. After 10 minutes of driving my car they indicated that they too experienced the problem. Wonder why my dealer cannot experience same????????? The independent facility told me they scoped the engine and fuel delivery system-no problems detected and indicated that it feels to them that the car shifts inadvertently into a higher gear; that the computer is sending false signals to the transmission. Unfortunately, the independent does not have the software to test the transmission. Has anyone else had a similar experience? I would like to make a recommendation to the independent on what action to take since the Lexus dealer will take none. Frustrated.

 

I've got 4 Lexus dealers in my areas. If everyone seems to be able to experience the problem except the Lexus dealer, I think I'd find another dealer. If it's really a problem, there's bound to be a reputable dealer somewhere.

If nothing else, ask the Lexus dealer in your area to go on a ride with you, and when the problem occurs, ask him if he notices it, too. He can't very well deny something that's obvious.

 

Check your air filter box, make sure it tightly sealed. Make sure you have a clean air filter and fuel filter. Make sure you have all you spark plugs changed. These things can cause your car to act up. Do all this and see what happens? If it still persists, at least you have a good tune up. Good luck

 

disconnect the battery for an hour, let the ECU reset

 

Thanks Too Cool/SC. I have two dealers in my area, both under the same ownership. I've had them ride with me and, yes, they do say they don't detect the problem. I've even had the service manager take my car and drive it for a few days. Guess what! That's right, "sorry we don't detect the problem." I have no confidence in my dealer. This is the same dealer whose technical advisor told me that my GX470 is not an all wheel drive or 4-wheel drive vehicle. I'm not sure where these technicians are trained, but I've come to the conclusion that I have to take this SC out of town to get it fixed.

 

Thanks Scorpio. I will try your suggestions, but the vehicle was recently tuned up and had a new oxygen sensor installed after the "check engine" light came on. The independent service facility did scope the engine and found no problem.

 

Thanks p-bateman. I tried your suggestion but that had no effect, unfortunately.

 

+1 scorpio, great advice. Surprising how even a dirty air filter can cause a big performance problem

 

did you reset the ecu by unplugging the battery for a couple of hours?

have you had your transmission fluid changed recently? ever done?

what about plugs? i noticed you have a 2002

any damage to the wheels or tires recently? do you hear any humming from the wheels?

 

A couple of years ago, I had an ugly hesitation that was worse if the car sat for a few days. It turned out to be a faulty TPS, which took the right circumstances for me to reproduce, and had the dealer's lead tech and his diagnostic PC with me.

 

I have the exact same problem with my 2002 sc430. I'm not going to be the guinie pig for the dealer to experiment with so I have just been living with it. Wish I knew the fix for it though. Good luck.

 

I live in the same area but have had good luck with the dealer in Southfield.
I have had great luck with Page Toyota service both for toyotas and my old
gs300 and my SC. You might try them.
Ask for Natalie or Barb in service, most helpful while others whose names I do not know are also good. Not so sure about service manager though.