i have a 99 gs400 with 60,500 miles and when car is warmed up idle will drop to about 500rpms or lower and feels like the car wants to shut off when i come to a stop, this does not happen all the time.could it be my plugs,i rest set my ecu and car felt better for about a week. can some one help?

 

lexoman,

A couple of guys had this problem before and had it checked out by Lexus service. I believe they said it was a throttle position sensor problem with a couple of them. Try doing a search for that, or "TPS". Some say it's just something that happens at idle when the AC is off. I know my 98 GS does it when I have the AC off and am sitting at a light or something, but it doesn't feel that bad. If it feels really uncharacteristic of your car (did it feel like that when you first got it?), then I'd say have Lexus check it out. I'm sure some other guys will give you much more detail than I will, but I hope this gives you a start.

Chris

 

thanks for the help, no started about a year ago, iguess its not that bad, but i will get it checked

 

Check the O2 sensors....TPS rarely goes bad...You can test the TPS if you adjust it left and right. Did your check engine light ever go on? High on emission tests? I say O2 sensors before the TPS...The O2 sensors should be replaced around 60k mi anyway...Good luck!

 

The check engine light never came on, i will have the o2 sensors
replace.thanks for all the info.

 

My ' 98 GS4 does it at times with A/C off. Not really a "bad" idle per se, most passengers would still wonder if the car's still running, but yeah...compared to how it idles at 650-700 rpm, the driver would notice the difference. Mine has never felt like it would stall at all, so, I live with it. Should a Lexus do this? No, but perfection is a wicked master, and it has to matter enough to you to want to chase after the culprit. At the moment, it isn't enough of a vex to make me want to run out and spend a couple hundred on diagnostics and parts. For others, it might be worth it.

 

Do a search, I don't think any Lexus dealer ever have a definite solution for this problem, at least for a few of us, myself included.

went to the dealer many times already, still no solution. The only major things I changed lately is SRT intake and TM plugs. I will probably take the TM out when I get a chance to see if it make any different or not.

Else, once in a while when the car act funny, I just have to turn the AIR, problem solve

 

hey guy thanks alot for the info. it is great to have a place where
there are other lexus owners.

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99 gs400
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