dek

Hi everyone, I have a problem with my 1998 GS400 that I hope someone can help me diagnose. The car usually runs great during the summer months but during the winter there is a problem while the engine is cold. Any time the outside temperature is below about 50-55°F it takes the car about 10-15 MINUTES to warm up before the accelerator has any effect whatsoever on the throttle. I can fully engage the accelerator right after turning on the car and the engine will just hold itself at a (possibly elevated) idle RPM. If I wait for the engine temp to rise to normal operating temperature, about half the time the car will eventually respond to the accelerator. The other half I turn the car off, then back on, and it drives normally. Any ideas that may help me guide me toward a solution would be greatly appreciated!

RoMiLex

Take the intake tube off and look to see if there is an obvious problem. If you have a check engine light, see if it relates to throttle body function. Check and see if its a cruise control function by seeing if it works correctly after its up to temp.

Not sure of how much you know about cars so just for thoroughness ill let you know that all the GS400s of our body style had a cable driven throttle body. The newer GS430 had what is known as drive by wire. Now its odd to hear that a cable driven throttle body is unresponsive because the cable will move the throttle body blade even when the engine is off.

So do you mean that you gas pedal wont move when the engine is cold? As in, when you step on the pedal it is hard or moves slowly. If so the throttle body could be bad and some part of it that lets the blade pivot has been damaged or worn and most definitely going to completely seize on you soon.

But before buying a new or used throttle body do the proper diagnosing and trouble shooting.

dek

Hi, thanks a lot for the reply to my question. Sorry it took me a while to return, as I did not realize i got a response!

I really appreciate the additional information you provided, it may just help me track down the problem.

Just for clarity, I will mention that the gas pedal does move freely, there is just no response from the car/throttle/engine itself. Fully depressing the gas pedal when it is in that mode results in 0 RPM change.

Listening to what you said about drive by wire vs cable driven, it does indeed sound like an odd issue to have, yet here I am. When I figure out what is actually causing my issues, I'll be sure to return and let everyone know. If anyone else has any suggestions/input/ideas, I am all ears.

Thanks Again!

kamlung

iTrader: (8)

i wonder if the butterfly in the throttle body is sticking in the colder temp... and when you step on the gas pedal, it feels like its going down but the cable itself is stretching...

you may have to take apart the intake and look at the throttle body and start the car on a cold morning...have someone step on the gas pedal and you watch from the engine to see the butterfly move... if it doesn't move, it is probably sticking... you may have to take it apart and clean/check for trueness...

DosyBoy

iTrader: (1)

Bad/weak battery

dek

Thanks for the input. I really appreciate you taking the time to consider my problem. Maybe it could be a stuck butterfly. The one thing is that last year, while trying to diagnose the issue with my local lexus dealership, they suggested we clean out the throttle body, which I had them do. Doing that didn't solve the problem on its own.

Last winter I thought it might be, and replaced the battery. Unfortunately it didn't fix the issue. It made me think the old battery was probably fine and it isn't related.

Mr Jokster

iTrader: (8)

Go under hood and move the throttle body by hand and see if it revs. Could just be the cable binding or the TB getting sticky with the cold air due to expansion of metals.

Caniac14

That's the best and simplest thing to try that will give you a better idea of whats wrong.