repman

i have noticed with my gs4 when you initally give it full throttle when the car is running between 20 to 40 mph it downshifts and there seems to be a hesitation like its not getting enough fuel or air it stumbles slightly then accelerates is this a common problem or is it something i should have checked out at the dealer the car is a 99 with 21000 miles and idles and drives smoothly other than this one problem any thoughts? thanks larry

LexusRules

its common.. it sucks really.. too much electronics! not like your supra i bet.. :eek:

try using e-shift and downshifting to the gear you want first if you think you're gonna have to take off.

repman

alex , thanks for the input you are right they have these new cars choked with electronic goodies. larry

fever

Same problem here. You really have to work the gate or buttons on the wheel to get what you want. Sucks.

JBrady

Yes, this is normal... however, I was looking at the Supra manual at the throttle body assembly and it uses 2 throttle plates. One controlled by the gas pedal, the other my the computer. For traction control the computer can reduce its throttle and thereby override the drivers foot. On the 98+ VVTi engines I am not sure how the drive by wire works as I do not have a manual (maybe someone will comment) but it may be possible to defeat the drive by wire by removing the second throttle plate (if this is how it is configured) from its throttle shaft. The computer would TRY to reduce throttle but the driver would be the only imput. Just an idea at this point, need to study this further as the LEAST favorite difference between my 96 LS and my 99 has been this drive by wire setup that causes imput delay and low speed jumpy throttle response.

repman

Jbrady, are you saying i am experiencing traction control? or just a lag in response because it is dbw, on the supra the computer is overriden with a switch of the button ,and the buterfly does not close. most of us who have went to a single turbo remove the trac butterfly compleatly . thanks for your input still learning about the gs.

JBrady

No, these cars use "drive by wire" to completely control throttle. This is what induces lag. I have heard it can be electronically improved a little but that still leaves much to be desired. Aparently BMW has resolved the problem but it is still anoying on our cars.

Even though the computer is controlling the TB there is still a cable from the gas pedal to the Tbody. After seeing the Supra diagram it made me think there may be something similar at work here. I would prefer to control my own TB thank you. For now I can't say because I do not have a diagram of the newer TB.

LexGS3

ive noticed something similar in my 99GS3... i notice it alot when starting from a stand still sometimes... and also when im slowing down like aproaching a light, and if im still rolling and I hit the gas again it jumps almost. Like from a stand still if it dont press the gas pedal just right it almost jumps forward. I dunno if my passengers notice it but i definetly do. How about you guys?