Hopefully you folks out there can provide some tips to my problem since the Lexus dealer says it's "normal" and can't help. I have a 2000 GS400 Platinum edition with about 7K miles. Ever since new, it has a slight hesitation when accelerating from stop--as if the gas cuts out for a split second and then it takes off. Under "gentle" or "normal" acceleration, the hesitation doesn't seem to be there. It's very noticeable under heavy acceleration. Makes no difference whether the engine is cold or hot or going straight line or making a turn. However, if I turn off the anti-skid control button, this hesitation disappears even under heavy acceleration. Ever since I bought my car, I have tried a total of 7 new GS400 (same year) and 1 GS430 and all experienced the same hesitation I described but disappeared when the anti skid is off. The dealer said they couldn't find anything wrong and advised me to leave the anti-skid off. As far as I am concerned, this hesitation is not acceptable and turning the anti-skid off is not an option. When I step on the accelerator on any car, I expect the car to move instantly particularly with a 300HP engine in a $55,000 automobile like the GS. Any ideas? Thanks.

 

Hi lexuspia,
the hesitation you are experienceing IS normal, the solution to this lies in after market products,ie. performance ECU's, LSD and TC. on my 98 gs4, i had that problem and had lexus change the ECU to an upgraded version, the issue was not totally solved but the hesitation was not as bad as before.Another simple way to eliminate this problem is to re-set the ECU you have now installed.This is done in one of two ways, (1) you disconnect the battery for 15-20 mins.then reconnect,(2) remove the ECU fuse located in the fuse box on the passenger side of the engine bay,i think is a amp fuse. this will remove the learned driving style, and restore factory settings. the difference is drastic,very little hesitation(your goal),this fix is however temporary as you will not be driving aggresively at all times, andyou computer will, over time once again settle into an average of you driving habits. fix again by resetting your ECU. some of the guys here reset ever two to three weeks. be warned however that you will smoke the tyres much eaiser after a reset. More info can be obtained by doing a searce on "re-setting ECU".
clive

 

LexusPia - your 'skid control' or traction control computer is only slowing the throttle response if it thinks your car is or is about to be skidding or spinning the wheels.

What size rims/tires do you have?

I have ZERO hesitation on my car, but I have gobs of rubber on the rear tires (275's).

 

My GS430 does the same thing and it is normal. Because your car has a drive by wire system. When you floor it the accelerator pedal position sensor have to comunicate with ECM, Vehicle Skip Control ECU and all the speed sensor before it give an o.k to the throttle motor. All whole thing will take about 1 second which is very fast considering for all the comunication the ECM have to makes.

 

VVT-i hit it right on the head, the drive by wire system is the only thing I don't care for on the GS. Even with the mods that I have I still feel the slight hesitation on my car...

Aloha

 

Me, no hesitation probs. It literally jumps when you step on it.

 

There's so much hesitation in my GS, I hesitate to post

 

98 GS 400 DOES THE SAME THING I THINK S BECAUSE OF THE FLY BY WIRE SYSTEM. RESETTING THE ECU DOES HELP A LITTLE. NEW C5 VETTE HAS FLY BY WIRE SYSTEM DOESN'T HAVE THIS PROBLEM.

 

-I've noticed this occasionally...but I thought it was just normal for automatics.

Also, the VSC system only activates when your vehicle speed is about more than 9 mph.

 

my 99 GS 400 has the VSC come on whenver my tires start slipping, even if its 3 miles anhour, i know this because it had been rainging and when i went to accelerate my tires kept going for a few seconds and i saw the vsc light come on and was going less then 9 mph.

 

futuregs: this info came directly from my owner's manual...but I think there are 2 systems...the traction control system (on from 0 mph) and the vehicle skid control system (on over 9 mph). Can anyone confirm this?

 

The hesitation is normal.
I think most of the GSs do that, I guess because of
the drive by the wire system, just what VVT-i said.
My 1st Gen. does the same thing. But resetting does
help for a little while.
Regards.

 

If this hesitation is norm on the GS400, can you tell me why I don't sense any of this hesitation on the IS, ES, LS, RX nor other brands like BMW 3, 5 and 7 series, Mercedes S class, Audis and the Corvette? I even have the pleasure of test driving a new BMW M3 and M5 and none exhibited this hesitation.

This hesitation as far as I am concerned is a safety issue since I have had couple of near misses when I was trying to merge into busy traffic from stop and because of the hesitation, the other car was almost in my back seat. It's embarassing and scary when your 300hp engine won't move at the instant you want it to move. Because of these incidents, I have now learned to switch off VSC right before I try to merge into heavy traffic. I think there is a problem but Lexus doesn't want to admit it just like the oil sluge fiasco on the Camry and ES they tried denying at first.

 

LexusPia,
I think we go to the same dealer in Peoria. I have never noted this particular to them but have noticed that my vehicle seems to accelerate better at part throttle. Then again, it is a 93 ls400 so it's not new.

Joe

 

Yeah it's all the computer systems involved in speed managment on this car. It's not the HP problem/wheel spin (although the hesitation will also occur when the car sense you are in a water puddle and is beginning to spin the wheels).. but what you are experiencing is normal. The computer has to do a few things such as use vvt-i to adjust cams, read pedal position, wheel spin, and open the throttle and probably a half dozen other system checks as it begings to go into WOT.