Question about Lexus SC 400

3 Answers

My lexus sc400 RPM is keep on pushing even if im not stepping gas pedal. im just worried to drive if my not stop even if im stepping my brake. also, the temp and gas needle's light is on and off. pls give me your professional advice. thanks.

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  • jojo gabat Nov 07, 2010

    as i remember......when i tried to wash the engine the RPM started to have that problem.

  • jojo gabat Nov 07, 2010

    if this is a caused of water, how come it still stays the problem since, it should be dry up by this time.

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3 Answers

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  • Master
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My advice is to take this car to your Lexus dealer. Toyota has had a recall on this very thing and it is dangerous to drive this vehicle with the accelerator sticking. You need to have this looked into. They can also fix the lights problem. I know of no recall on your model Lexus but there has been such an uproar on Toyota vehicles with accelerators sticking that I would not hesitate to ask your Lexus dealer to fix your vehicle free of charge. Call Lexus if they balk at repairing it. Toyota does not want any more bad press on this problem. Be nice and ask for a courtesy repair.

Posted on Nov 08, 2010

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  • Lexus Master
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Sounds like the iacv or idle air control valve is not functioning correctly, or there is a vacuum leak causing more air to enter the intake than normal and the computer is trying to compensate by increasing the RPMs on the engine to maintain good emissions from the tailpipe with the most complete combustion by increasing fuel through the fuel injectors.

It could also be a computer that is not controlling the iacv adequately to have a smooth idle.

I would have the car's computer scanned for fault codes that can lead to a diagnosis of a system in the car not functioning to specs.

If the RPM is out of spec and too high, something is bound to be recorded in the computer, if it is functioning correctly.

Posted on Nov 07, 2010

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  • Lexus Master
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Hi.

No need to tell you that you have a major problem.

To start there are several recalls for similar problems on Lexus. As first thing I would call the nearest dealer providing car year, model and vin number, asking if there is a recall affecting this model. If there is a recall the vehicle will be repaired at factory expenses.
As far as I know , the only recall issued is for the 1992 model, and concerns brakes.
better calling the local dealer to ensure. Use this page to find a dealer.

If there is no recall, then you cannot fix this without having testing done from a good mechanic. The accelerator alone can be caused by a defective accelerator pedal system, or by an EGR valve that is opening and closing, or if RPM variation is small, by a problem with vacuum, IAC control or air intake.

If revving increment is a lot, like when you push down the accelerator pedal, then problem is either electronic injection, throttle body or accelerator system. I think this vehicle uses an hydraulic system (no steel cable connected to pedal), then a malfunction affecting the pedal far from being unlikely.

The lights turning on and off however point in direction of an electronic problem. Lexus SC400 are known for having several electrical problems.

Try disconnecting the battery cable. If that fixes the problem, drive to a garage near to you for a revision. If that does not fix the problem and acceleration is consistent and affecting driving, then do not drive the car. Call a mechanic to have a look, or have it towed to the nearest garage.

Regards.

Ginko.

Posted on Nov 06, 2010

  • Ginko
    Ginko Nov 07, 2010

    Re:" when i tried to wash the engine the RPM started to have that problem."


    Check the two connectors to ECM (main computer module). The ECM is a metal box located under the hood.

    Check connection to EGR valve.

    Check ground cable from battery to engine block.

  • Ginko
    Ginko Nov 07, 2010

    Re":if this is a caused of water, how come it still stays the problem since, it should be dry up by this time."

    That is probably a guess from someone who read your comment about cleaning the engine. If water was sprayed on top of electrical parts it can surely cause damage that will not be fixed by drying up. However there is no clue that points at water damage problem. If the problem happened after cleaning the engine, more likely some of the electrical connection has been moved and it is causing the problem.


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1 Answer

Why wont my car idle, drives fine but I have to keep accel pedal pushed in to stop RPM dropping below 700 RPM & stalling?


have the fault codes read to find the sensor that has failed
if it happening when you have the foot on the brake, it could be a problem brake booster

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Tip

How to TEST A TORQUE CONVERTER ON A Automatic Transmission


Symptom : chattering or vibration while idling, and in Park.
Transmission sluggish upon Accelaration..

Step 1: chock Block all your wheels, and put your Auto emergency brake on (applied).

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I have a lexus sc400 1994 and it turns off while driving. Im able to turn it back on but it turns back off when i take my foot of the pedal


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I own 1999 lexus es 300 and the transmission is not changing from 3th to 4th gear even if i got over 4000 rpms... 'o/d' its not working when im driving 50mph i wonna go down 1 shift im turning off...


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You will/should take the car into a place that specialises in the Lexus model. then ask ONLY for a "Quote' as to costings and what needs to be done, get appraised of it all, and go from there.

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1 Answer

Lexus sc400 electrical problem


the computer is bad and also these cars are known for the insturment clusters to go bad along with the computer. get them both fixed and it will solve your problem.

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