My GS400 is all stock and i have this problem. I only notice it when its nice and warm, then again, that's the only time i drive it and have the windows down to hear it. The dealer heard it too but wer'ent sure what to fix but werewilling to try if anyone had a fix. They called Lexus in cali and they didn't know anything about it.

I just drive with either the lights or climate on.

 

I have an 01 GS430,

I do idle around 550 RPMs average, but it has never hesitated, or gone lower than 550 RPM's.

I used to idle at 700 RPMs, but after I reset the ECU the idle went down. On a side note, I never run the AC, just leave the windows open. (Feel cooler )

 

BANANA

i actually got around to clean my MAF sensor. car idles just a bit smoother. but when the engine is hot, like after driving home from work on the freeway, you can feel a bit of roughness. i just used brake cleaner and sprayed inside, got the filaments shiny. after that i reset my ecu.

but when my car is warmed up, but not yet on the freeway, it's pretty smooth. rpm is still around 400, so i doubt the rpm has anything to do with the roughness, it's something else. but again, when my engine is hot, like after getting off the freeway, some of the roughness starts to creep back when i'm at the stop light...not immediately, but gradually when i'm stopped.

 

As a fellow 99 GS400 owner my idle is low without A/C as well. To think the guys at Lexus are unaware of any problem is about like Iraq saying they have no WMD. We know there's a problem and Lexus knows there's a problem. As much as I'd like to think otherwise, I actually think the solution is "cost prohibitive" therefore denial is the only way to go. I could be something "expensive" to replace or fix.....or maybe the powers that be at Lexus feel the problem doesn't justify fixing(trivial anyone?). Now don't misunderstand my statements, I think a car as expensive and refined as the GS shouldn't have this problem, but I also don't let it get in the way of my admiration of this wonderful car!!!

 

My dealer kept telling me that he contacted Lexus and they say they are unaware of this problem on a large scale. Even after I told them about this message board and how many people have experienced the issue.

He did change the charcoal canister, and while this didn't help the low idle problem, it has kept it from outright dying on me again. (at least so far)

 

According to my dealership, Lexus IS aware of the problem now. My dealership is working overtime trying to do whatever they can to fix my GS. It has already spent 5 days in the shop in an effort to fix this problem.

 

UTGS400,

please keep us up to date on your situation. if your dealership is able to resolve this problem, please let us know and hopefully the mods can make it a sticky.

 

A little late, but I, too, have the low idle problem when the A/C is switched off.

My bone stock '99 GS400 occassionally idles around 400 rpms with the A/C off and in Drive. When it's close to 400 rpm, the car also shudders a bit. During warmer weather, it seems to do it more often. But so far, however, the engine has not idled so low that it stalls. It is quite a weird issue. . .

 

I'm chiming in on this thread to 1) voice my mutual frustration and 2) I'll be notified when ppl post comments. I really hope this gets figured out. My car has the identical problems to that described, however I drive a '95 LS400. Sounds like it's a problem with mid to late 90's 400 series (LS,GS, SC). Beng that the ECU sets RPM, and it doesn't trip a code when the RPM's sit at 400RPM, I too suspect the programming is the problem.

Colby

 

I too have an idle problem but I have a 95 LS400. At stop lights the car drops to 200 or so rpm and then gradually comes back up to around 500 (sometimes). Then at other times when I am cruising on the highway I go to get off an exit and as soon as the car rpms drop to about 1000 from deceleration the rpms drop to around 100 and it almost dies each time. If I turn off the car and then turn it back on it goes away for awhile.

I did replace the TPS sensor as well as the spark plugs before. With 122k on the odometer I think this problem is very premature for a car known to last well over 200k. This problem definitely deserves to be brought to Lexus' attention through a class action lawsuit of some sort.

Jamie.

 

'95 LS400 here and this exact same problem happened to us the other day (twice in one day). Sounds like it's happening to mid to late 90s 400 models. It's disheartening to know Lexus has no idea what is wrong...because it is potentially a very dangerous problem.

 

Did anybody try my charcoal canister idea?

 

Hey guys

I just purchased an '01 rx300 and I noticed a low idle on it as well. My idle sits at around 500 rpms and I think it should be around 750. It doesnt die or stall but it makes the most annoying humming noise. I went to the dealer and they said that they would charge me just to look at it. Do you guys know if this problem would be covered under the powertrain warranty? I have 54k miles on the thing and I would like to have it fixed before i get past 70k.
My previous car was a 240sx and it idled rough sometimes cause of the carbon build so I cleaned by spraying throttle body cleaner into the IAV ( i think) its the hose that feeds air into the engine while idling.
Does anyone know if this possible to do on an rx300?

Thanks in advance

 

well lately with the cold weather, my gs idle's very smooth, but i know this is only temporary. cuz when we have the hotter weather again, the idle will be rough once more. *sigh*

 

I have low idle too, usually around 400 rpm. but Only when my AC is off..
Keep your AC on and it should be okay