Navidf

HI everyone
This is my first post! I just purchased a GS400, 1998. I have been reading some older posts regarding the various rattles, shakes, etc. I have many of those same issues, but since the car is still under warranty, the Lexus dealer at Riverside, CA has been wonderful about addressing them. I mentioned to them the engine hesitation on acceraltion which I am experiencing and was told it is normal for this car. I had read some posts about a ECM or ECU update to solve this issue and brought it up to their attention. I was told my car was not part of the VIN # range for that repair (my car was built on 5/98). Even though this is most likely an old topic for all of you, I would appreciated any help regarding your experiences.
Thanks

theanimala

I noticed the hesitation when I bought my '98 around 6 months ago. To be honest, I think I just got used to it. Every car drives differently, and the change from my 94 SLS was quite obvious.

I never had the dealership do anything to it. I think just getting used to it, and using the eshift buttons has made a big difference.

Mean Gene

N - Welcome to the Club! FWIW- I had my ECU changed out for the "improved" one & starting improved but the hesitation is still there & I've test-driven every GS4 my dealer had & they all do it to an extent. It's got something to do with the drive-by-wire throttle system. Even though there's an actual acceleration cable, it relies on sensors for feedback before activation & apparently those sensors are the problem. Kinda funny that the 'Vette has the same style system & it's "Hold On" when U floor that car!? Unless U want to install a torque converter, U'll have to get used to it like Animala says.

Navidf

Thanks for the feed back.
It seems strange that they make a 300HP car hesitate on purpose!!! If this problem can be solved by an after market solutions e.g. swift-racing, rod Millen, etc, then that means Lexus can do it as well, doesn't it?
Is this hesitation still an issue with the GS430s?

Mean Gene:
How did you manage to have them give you the improved ECU? (is this the same thing as the Progressive Power Steering (PPS) ECU for which there is a Jan 98 TSB?)
I noticed you have a GS400,
99 model year and there was still an "improved ECU" available for your car!
I have a 98 model year, so it seems logical that one should also be available for me. Should I push this issue with the dealer?
Thanks again.
I am happy to be joining in the discussions on this forum

mooretorque

Navidf, welcome!! Is this your first Lexus?? If so, dealer treatment should be a welcome surprise.

I haven't driven the GS prior to the 01 that I have, so I can't directly compare, but throttle tip-in is not abrupt on the 430 under normal circumstances. Lexus is VERY big on seamless, creamy responses, but I can't go so far as to say I have any hesitation in the initial off the line response. I agree that the drive-by-wire throttle could certainly produce such a situation. And a TC can certainly remedy the situation, plus providing stronger (like we really need it!!! Then again, I have a certain fondness for the " too much is never enough" school of thought.) acceleration.

Mean Gene

N - I had some trouble with my dealer changing my ECU - got the "They all do it" response when I said that the starting sequence was too long. I realize that the sensors must find everything within specs before they'll let the engine light off but it took awhile to get used to a $50k car taking 3-5 seconds of cranking to start. I had to go over their heads to the Regional Lexus customer satisfaction line & then they overnighted a new ECU for me!! As I said before, the off-idle throttle response still wasn't what I expected but that's the drive-by-wire situation. FWIW - here's the part number for the "improved" ECU - see what your dealer will do for ya but I had only had my GS for 1 month so I guess I could've used the "Lemon Law" if necessary! It's listed as an "Engine Control Computer " & #8966630050. U can also pull the ECU module & check the numbers yourself. Good luck & don't be afraid to play hard-ball!!

RealMarty

I have an early '98 GS400 and I've never noticed slow starting or hesitation off the line.

I do believe the tranny shifts more crisply with it in manual even without using the e-shift. I find e-shift to be very slow to respond...to the point I rerely use it. It's a major disappointment compared to a 5-speed manual. It does help in downshifting from 5th to 4th for passing but even then the downshift seems to take forever.

Marty

Jazziz

I don't know if you saw an earlier post for the old board long ago, but I've noticed a slight difference by resetting the tranny ECU. Disconnect the battery for about 30 min it removes the "intelligence" from the ECU that has adapted to your normal driving style over time. This is only a temp fix because it will relearn again in a week or two unless you drive WFO all the time. I may have to get a permanent cure for my problem from Swift Racing.

CJGS4

Has anyone had rattles in the front dashboard of their GS? Mine has been rattling like crazy and after 5 trips to Longo Lexus they still haven't been able to solve it.. Every time they say they that they've insulated it but it doesn't seem to be working... Anyone have a solution?

-Chris Y.

chowder

if you're referring to a rattle that is in the vicinity of the driver dash left front vent, then i've heard it. i've been trying to figure out where it comes from. i'm at 19K and it's very subtle. if i do nothing, it "settles down" and goes silent after a short while into a drive. i can only hear it during bumpy road conditions. i can mute the rattle by pressing ever so lightly on the part of the dash directly below the odometer.
i am only going to the dealer when i figure it out. the last thing i want is some tech to take apart my dash and not get anywhere.

bitkahuna

iTrader: (20)

I suspect because the car goes into 'Power' mode when manual is selected.

RealMarty

I don't think so bitkahuna.

Its not changing the shift points and tendency to more easily downshift as it does in power mode. It just seems to move from one gear to the next more crisply with less hesitation between gears.

I've suspected that the computer doesn't retard the spark just prior to changing gears as much in manual as it does in the full auto mode but I have no data to bear it out.

Marty

bitkahuna

iTrader: (20)

One other thing you can try is adjust the tilt of the steering wheel slightly. Sometimes a rubbing of the steering column and the dash can cause such sounds.

TXSTYLE

iTrader: (1)

I too have a 98' model with about 36k miles racked up. I have never sensed hesitation in normal, power, or manual modes. Have you isolated these instances to cold or normal operating temps?

bitkahuna

iTrader: (20)

Couple of things...

One - I think I found my GS a bit quicker to respond after putting in the drop-in K&N filter, so you might try that.

Two - You may be having problems with bad gas (the car, not you ), bad air, altitude(?), or some other factor like that.

I have never felt that my car 'hesitates'. Just VROOOOM.