did you try replacing the TB

 

the tb assembly.. no.. all the sensors.. yes.

 

random update.. so, for like a week it would sort-of work... If I was even slightly pressing the gas pedal while it first started it would work normal, I could rev and the throttle would respond but as soon as it dropped to an idle RPM speed it would go back to being effed up and not responding at all... Like I said.. That happened for about a week and this was 2 weeks ago.

If anyone can identify the problem and I fix it and it works I will paypal them $100... this is not a joke!

 

Mostly likely it isn't your o2 sensor. Run a pre-test on your ECU, I'd believe thats what causes all those issues since you'd already replace other sensors. Or check main engine wire harness to see if it connected properly...

 

I never knew hte GS400 had a butterfly motor...is this for VSC and traction control?

may sound stupid but I hope you didn't put the MAF sensor the wrong way

 

haha, nah... The MAF is in the right way.. And I guess the motor is for the VSC?? I have no idea... I am an old Honda nut... I am slowly learning the way of Lexus.. haha.

and what is a pre-test/how do you run a pre-test on the ecu?

 

at least that's out of the way
as someone said before me, o2 sensor?

 

those have not yet been replaced, unfortunately I don't know which one it would be... is there a way to test them using an Ohm meter?

 

80-90% of o2 sensor faults are its heating element. The heating element is powered via the 2 black wires and it resistance is approx 11-14ohm.

On the GS3, one black wire is connected to +12v supply, the other black wire goes to an ECU internal power transistor to connect it to GND on power up. The other 2 wires are data out (AC signal, you need an oscilloscope to check operation) and the last wire is GND.

There are 4 O2 sensors. Bank 1&2 sensor 1 (nearest engine) are the main control sensors, bank 1&2 sensor 2 are the check/verify cells that might not throw a CEL on failure. The main sensors will always throw a CEL on failure

 

Good to know! Thanks! I'll see about ordering some O2 sensors and seeing if its them... but would a faulty O2 sensor cause the Electric Throttle Control System (ETCS) to completely stop working?

 

Ouch that hurts. I left mine sitting for a few months and was cleaning and left the key on.i thought I burnt something up with the ignition. Now I am trying to get rid of the old gas. I thought at first it was no spark but I sprayed a little starter fluid in the intake and it ran for a sec. So i disconnected the fuel line to the injector. No I need to figure how to jump the pump relay. I just found out the relay is in the trunck. That is why I couldn't find it under the hood.

My key broke off the steel part. The electronics for the key on a 99 gs 400 is just for the alarm, is that correct??? I cant remember if there was something on this car that the key needed the electroni part. i remember starting my car with the silver vala key or was it my 93 gs? humm

i am curious to see what you come up with.

 

So, finally decided to give up. Taking the Car to Lexus of Nashville North this coming monday to have them tell me exactly whats wrong with it.. Wish me luck!

 

That sucks..

I got lucky, there was a drain plug in the tank. I drained out all the gas put some new gas in and it fired right up.

 

So I took it to Lexus that Monday... Basically paid $113 for a car wash on a rainy day.. Threw codes:
P0120 - TPS
P0121 - TPS
P1120 - APPS
P1125 - TCM
P1126 - Magnetic Clutch
P1128 - TCM lock
P1129 - ETCS

Lexus tech said that most of the codes are in history where I have been swapping out parts and doing the work on my own and he still believes that its the APPS.. So I purchased an APPS sensor from CL member jroring and will be installing that Saturday. I am to the point now where I will just start replacing parts until it starts working again... Hopefully this APPS works, but I doubt it will. Who knows..

 

installed new APPs, still the same problem but this time the TCM would operate right after the ignition would turn on but then stop as soon as you let off the throttle.. checked the TCM and it was fine.. adjusted the TPS and BLAMO!.... now it is working!