SC430 power lost on highway.
Rookie
Joined: May 2011
Posts: 64
Likes: 3
From: NC
Hi, any update on this? After cleaning the MAF and it not happening again, after 6 months it's started again. Unfortunately, cleaning the MAF doesn't help this time. For everyone else, it can happen within 5 mins of starting out, or 2 hours later, at 35 or at 65. Like he said, the speed drops and you have to press the pedal down a couple of inches to maintain the speed you were going. And response is very very sluggish. Then within a few minutes it's back to normal. It is a bit scary, you think the engine will turn off, but it never does. With cruise control you don't notice it, because it is maintaining the set speed by operating the throttle.
Driver
Joined: Apr 2008
Posts: 166
Likes: 1
From: Alberta
Sounds to me it is the throttle controller module at your gas pedal, there is no "Throttle Cable" in these cars, they are "Drive By Wire". There is a potentiometer at the gas pedal that sends a signal to the ECU then it sends a signal to the throttle body control motor in turn opening up the throttle plate to the corresponding position. If your throttle control at the pedal is faulty it will exhibit the problems you are experiencing. When you are set on cruise control it eliminates the gas pedal. If it works fine on cruise I would bet if you change your pedal module your problem will be eliminated.
Rookie
Joined: May 2011
Posts: 64
Likes: 3
From: NC
I think it still exhibits the problem while on cruise control, but it's not noticeable because the speed is being maintained. I can maintain the same speed by depressing the accelerator. Once I turned off cruise control in the middle of an "episode", saw what was happening, turned it back on, and it slowly came back up to speed.
Driver School Candidate
Joined: Oct 2015
Posts: 1
Likes: 0
From: Fl
I have replaced the accelerator pedal assembly and it solved all my problems It is just like if I was driving an other car the car now have a good acceleration and the problem never came back . The pedal assembly can be found on EBay.
Pit Crew
Joined: Mar 2015
Posts: 125
Likes: 45
From: Massachusetts
When you say that it loses power when you are driving at 60 + mph, do you mean that your speed is steady at the point of power loss or that when you attempt to accelerate at that speed that you lose power.
If it is when you attempt to accelerate that you lose speed or the engine just doesn't respond, you ought to try resetting the engine ECU. Here are the instructions for that:
If you want to reset the ECU without losing your seat and stereo settings,
perform the following procedure:
1. Get in your car and insert key. (It doesn't matter if you close the door or not.)
2. Turn the key to the on (not start) position.
3. Press the gas pedal to the floor.
4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position
(don't remove the key), then release the gas pedal.
5. Wait 2 minutes.
6. Remove key.
7. Done
If it is when you attempt to accelerate that you lose speed or the engine just doesn't respond, you ought to try resetting the engine ECU. Here are the instructions for that:
If you want to reset the ECU without losing your seat and stereo settings,
perform the following procedure:
1. Get in your car and insert key. (It doesn't matter if you close the door or not.)
2. Turn the key to the on (not start) position.
3. Press the gas pedal to the floor.
4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position
(don't remove the key), then release the gas pedal.
5. Wait 2 minutes.
6. Remove key.
7. Done
Lexus Test Driver
Joined: Dec 2014
Posts: 8,213
Likes: 949
From: Fl
When you say that it loses power when you are driving at 60 + mph, do you mean that your speed is steady at the point of power loss or that when you attempt to accelerate at that speed that you lose power.
If it is when you attempt to accelerate that you lose speed or the engine just doesn't respond, you ought to try resetting the engine ECU. Here are the instructions for that:
If you want to reset the ECU without losing your seat and stereo settings,
perform the following procedure:
1. Get in your car and insert key. (It doesn't matter if you close the door or not.)
2. Turn the key to the on (not start) position.
3. Press the gas pedal to the floor.
4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position
(don't remove the key), then release the gas pedal.
5. Wait 2 minutes.
6. Remove key.
7. Done
If it is when you attempt to accelerate that you lose speed or the engine just doesn't respond, you ought to try resetting the engine ECU. Here are the instructions for that:
If you want to reset the ECU without losing your seat and stereo settings,
perform the following procedure:
1. Get in your car and insert key. (It doesn't matter if you close the door or not.)
2. Turn the key to the on (not start) position.
3. Press the gas pedal to the floor.
4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position
(don't remove the key), then release the gas pedal.
5. Wait 2 minutes.
6. Remove key.
7. Done
it works!!!
1st Gear
Joined: Oct 2024
Posts: 1
Likes: 0
Still out there?
Hi everyone, I've own my Lexus sc430 for a couple of years now and I've been experiencing some problems. It's ia 2002 sc430 with 77k miles. When I drive on the freeway at around 60-70mph the car decelerates. Everything else is working. The car feels like I let off the pedal, but I really didn't. I went to the my mechanic and try to see if any codes came up but nothing. Also hooked it up to the scanner while driving and when the problem happens still no codes. the mechanic cleaned the MAF sensor and throttle body. He said he thinks it might be fuel filter problem. I searched on the forums and read some people have the same symptoms as me, but no one really talks about a solution. I read that the Throttle Position Sensor could be the problem, but when I told my mechanic he said he doesn't think that it could be the problem or else it would throw a code. The mechanic also thought that it could be that the tires are low on air so he filled them up and drove home and had no problems. but I feel its still might happen. any suggestions?
Pole Position
Joined: Jan 2020
Posts: 2,738
Likes: 544
From: CA
There are a lot of good suggestions in this thread, and some owners have been able to solve the problem with resetting the ECU. I would also suggest to owners with this problem that they ensure all their brake components are clean and lubricated, so as not to bind. A slight drag on one pad can heat up the whole caliper to the point where it may bind and slow your roll. Also, if I had the problem and the simple solutions weren't working, I might investigate the fluid level in the tranny, or do a 4 qt drain and fill via the cooler lines.
Driver School Candidate
Joined: Sep 2024
Posts: 20
Likes: 15
From: CA
Missing something.
I know this is a very old thread, but I noticed something that wasn't mentioned. I had the same problem with a Tundra 4x4 with a 4.7 V8. I occasionally lost power when excelerating an never threw a code. Even trips to the dealership service department didn't do anything but put a scratch on my truck and charge me $200.00 for no problem found. Now, to solve the mystery it was...... the knock sensor on top of the intake manifold. Changed them out and problem solved. If the sensors think the engine is pinging, they will retard the timing making you loose power. When the sensors think the pinging is gone, the alllow the advance of the timing back to normal.
And.. never use Seafoam! That stuff is garbage.
And.. never use Seafoam! That stuff is garbage.
Thread
Thread Starter
Forum
Replies
Last Post
sixonemale
SC430 - 2nd Gen (2001-2010)
14
Jun 29, 2011 10:56 AM
