gstaples

I have an 2004 LS430 that has an unusually strong creep at idle. Some creep is normal but this car moves forward at idle even up a steep hill. At idle on level ground the car will not decend below 20 mph without applying the brakes. The pressure is strong enough that the brakes make a poping sound when releasing them at idle.

I have driven several 2004-2006 LS430sand haven't found any that exhibit this problem. The dealer tells me that the idle setting is controlled by computers and there are no dealer adjustments. They also indicated that Lexus had to retune the idle on LS430s because the alternator wasn't charging charging the battery adequately at the original designed factory settings. I have escalated the problem to Lexus but have been told that the vehicle is within specs. This seems to be the standard Lexus answer to problems they don't know how to fix. I don't know if it is the idle or a problem with the transmission. The transmission was replaced in a recall by Lexus.

I love the car but this idle thing is really getting on my nerves. I would appreciate knowing if you have had this problem and was Lexus able to fix it.

BMcD430

Something is definitely wrong if your car goes 20MPH at idle. It's just a thought but have you tried removing the battery cables and letting the car sit for a bit and reconnecting? On many cars this resets the ECU and the trans ECU. You then drive normally and the computer "relearns" it's settings based on your driving. Not sure if it works on a Lexus. You lose all your radio presets BTW but that is easy to redo. Good luck!

Bruce

Nauticalx

Thats distrubing, I would suspect too high an idle RPM or a torgue convertor that's not willing to let the wheels sit still while the engine is turning. Are you in the "power" mode? I wonder if that would have something to do with it. I would look at the tachometer and see what RPM you are idling at and compare that with others. That would be an easy way to tell what you are idling at.
I do not buy the claim that dealers cannot adjust the idle, idle control modules are programmable and in a car as advanced as the LS it should be no different. After all, how could they have bumped it up for not charging the battery enough in the first place? Wouldnt it have to be adjustable for it bumped up?
I would have your dealer pull the service history and see if a dealer has bumped up the idle on your vehicle and when it was done. Then ask them to undo it for a test.

Good luck and keep us posted.

Nauticalx

Also do do what BMCD suggested. Up hook the thing for a night and see if that doesnt erase what any dealer may have re-programmed into it.

gstaples

The RPM seems to be only slightly higher than other Lexus's; however, the RPM on mine drops more when moving from Neutral to Drive than other LS's. I interpet that as the Trans is loading the engine more than on other LS's; so the torque converter could be the problem. I read another post but not sure it was on the current model of LS in which the trans was receiving an RPM signal that was too high. As previously mentioned, the transmission was replaced on recall on my car. With a warm engine, mine will idle in neutral at 8-900 RPM and at 700 RPM in drive. Having the Air Condition On or Off doesn't seem to make much difference in RPM.

At my request, Lexus Customer Service is arranging a meeting with the Lexus Regional Service Manager. I will ask him if unhooking the battery will reset the ECU. I wouldn't mind losing the radio presets but I really don't want to have to transfer the telephone #s back into the Bluetooth. With a Motorola cellphone, the telephone #s have to be transferred one at a time. That takes 2-3 hours..

I previously had the dealer print the entire service records on the car. The transmission, fuel pump and navigation DVD were replaced under recall. There is nothing regarding changing the programing on the engine idle but the battery was replaced. Perhaps they reprogramed the RPM when the battery failed. The ASW/Anti lock Brake actuators were replaced twice as the low tire pressure light kept activating. They changed the program on the Antiskid system which was prematurely activating the alarm. Also, the park assist system failed twice.

vcheng

Have the fluid level checked PROPERLY: It may be too high.