OK, I tried to do a search but perhaps my search terms are incorrect.

We've had a weird behavior in the GS430 for some time. At first I thought it was some sort of hesitation. As I've driven it more I now think something is goofy in the electronic throttle.


Here's what I can tell. If I accelerate, then just jump to cruise control I almost never notice this. However if I'm driving at a steady speed the problem comes up.

What happens is I'll be driving at a steady speed, then all of the sudden it seems like the power has dropped off, and you have to push the throttle pedal alot farther to maintain speed. Then a little while later, it's back to normal again.

When this occurs even pushing it all of the way to the floor results in not full power. It doesn't seem like a drag on the motor, just like the throttle plate isn't opening as far.

It's Most noticeable in power mode. And least noticeable in snow mode. Though if I'm in power, and I switch to now mode while the power has dropped, I can feel a small change in the throttle mapping. Though not much.

Happens in winter and summer, though seems to happen more often in summer. It is not affected by running the Air Conditioning at all though, as in I can have the A/C off and even the whole entire climate control unit turned off and the problem will still occur.

But, running Cruise Control and you don't notice any problem or change.


I'm fairly good with fixing things, though I'm not sure where to start on this problem. Has anyone heard of this before? Know where I can start looking to diagnose the problem?

Oh, no check engine light, nothing else really seems to be wrong with the motor. Only 60k miles on it. Problem does seem to be occuring more frequently as time progresses though.


Thanks guys

 

Hm... Nobody has any ideas?

Does this sound like a TPS sensor? Or a APPS sensor?
Where is the APPS sensor on the GS430's, in the cab, or on the throttle body?

 

Just ordered a TPS and APPS sensor. Gonna replace them and see if that makes any difference.

 

Well, did that fix your problem? Just ran across your post. I am having the same problem on 1998 GS300

 

Good so I'm not the only one, *lol*

It feels wierd, like I'm driving along at a steady speed with traffic and suddenly the car starts slowing down, like I had thrown out an anchor or something.

To answer your question, Just ordered the parts from RockAuto yesterday. They should be here next week and I'll try the install then.

 

master brake cylinder

 

Uh, what? Why would that cause the aforementioned symptoms? Occasional Vacuum Leak?

 

funny i started to have the same problem recently i think it has to do with the throttle body one of the sensors.. i had it check but when they were checking it it worked find my luck right? lol it doesnt happen all the time but sometimes it happens

 

Kinda an update on this thread.
I never was able to figure out what could be causing the problem.
It never got any worse, it was just an annoying behavior of the car

 

After changing the tps and app did u had to reprogram the ecu?

Also check for vacuum leaks, all the hoses underneath the engine cover. Lastly, clean ur MAF sensor. Try those.

 

I just drove around the behavior until I sold it.
It would never do it accelerating, and on cruise control if it did it there was never any indication. So I just used cruise almost exclusively until I sold the car.
Sorry I couldn't be more help.

 

What u drive now