bluestu Posted February 17, 2006 Author Share Posted February 17, 2006 You're correct. The vibration only becomes noticeable when the engine has warmed up and the rpms drop to 6k. Put the car in neutral and the rpms increase to 8k, and the vibration is totally gone. It has something to do with the AWD transmission being engaged. I called Lexus, and of course they hadn't heard of the problem. Quote Link to comment Share on other sites More sharing options...
stonecutter Posted February 17, 2006 Share Posted February 17, 2006 You're correct. The vibration only becomes noticeable when the engine has warmed up and the rpms drop to 6k. Put the car in neutral and the rpms increase to 8k, and the vibration is totally gone. It has something to do with the AWD transmission being engaged. I called Lexus, and of course they hadn't heard of the problem. Do you mean 600 and 800 rpm's rather than 6k and 8k ? If it is really 6k and 8k, then this is bizarre. Quote Link to comment Share on other sites More sharing options...
bluestu Posted February 17, 2006 Author Share Posted February 17, 2006 You're correct. The vibration only becomes noticeable when the engine has warmed up and the rpms drop to 6k. Put the car in neutral and the rpms increase to 8k, and the vibration is totally gone. It has something to do with the AWD transmission being engaged. I called Lexus, and of course they hadn't heard of the problem. Do you mean 600 and 800 rpm's rather than 6k and 8k ? If it is really 6k and 8k, then this is bizarre. Sorry, my mistake. I am getting old. Quote Link to comment Share on other sites More sharing options...
SKperformance Posted February 17, 2006 Share Posted February 17, 2006 too much to read ,did you clean your throttle body and iacv? how are the engine mounts Quote Link to comment Share on other sites More sharing options...
tta300 Posted February 17, 2006 Share Posted February 17, 2006 Yes, if your RX is over 90,000 miles, all the following will improve idle vibration and keep your RX in top condition: -new engine mount -new muffler mount -new iridium plugs -new throttle position sensor -cleaned throttle body -cleaned idle air control valve -fresh type IV transmission fluid -consistently using synthetic engine oil every 4-5000 miles Even by switching engine oil grade from 5w-30 to 10w-30, you'll feel the difference in idle vibration. The truth is the idle vibration can be improved but never be eliminated. It applies to Toyota/Lexus using the same 3.0L V6. Excessive vibration can be a sign of engine sludge, or partially blocked oil pickup screen. This will be the last thing we want to happen to our RX. Quote Link to comment Share on other sites More sharing options...
stonecutter Posted February 17, 2006 Share Posted February 17, 2006 Yes, if your RX is over 90,000 miles, all the following will improve idle vibration and keep your RX in top condition: -new engine mount -new muffler mount -new iridium plugs -new throttle position sensor -cleaned throttle body -cleaned idle air control valve -fresh type IV transmission fluid -consistently using synthetic engine oil every 4-5000 miles Even by switching engine oil grade from 5w-30 to 10w-30, you'll feel the difference in idle vibration. The truth is the idle vibration can be improved but never be eliminated. It applies to Toyota/Lexus using the same 3.0L V6. Excessive vibration can be a sign of engine sludge, or partially blocked oil pickup screen. This will be the last thing we want to happen to our RX. Ok, most of the listed items are very intuitive, but why/how do transmission fluid and motor oil affect idle ? Quote Link to comment Share on other sites More sharing options...
tta300 Posted February 18, 2006 Share Posted February 18, 2006 It won't make any difference for a newer RX. By the time yours is over 6 years old/90000 miles, you will feel the difference. As for any mechanical reason, Toyota/Lexus should have figured out a good explanation before we do. Quote Link to comment Share on other sites More sharing options...
chiks Posted February 22, 2006 Share Posted February 22, 2006 OK. This time the diagnostic expert sat with me and agreed that there is a "booming" sound coming when there is load on the engine at idle. Let us see what his solution is going to be......... Quote Link to comment Share on other sites More sharing options...
stonecutter Posted February 22, 2006 Share Posted February 22, 2006 OK. This time the diagnostic expert sat with me and agreed that there is a "booming" sound coming when there is load on the engine at idle. Let us see what his solution is going to be......... Knock maybe ... ? What grade of gas do you use? Quote Link to comment Share on other sites More sharing options...
chiks Posted February 22, 2006 Share Posted February 22, 2006 Premium. Quote Link to comment Share on other sites More sharing options...
JohnS Posted March 9, 2006 Share Posted March 9, 2006 Yes, if your RX is over 90,000 miles, all the following will improve idle vibration and keep your RX in top condition: -new engine mount -new muffler mount -new iridium plugs -new throttle position sensor -cleaned throttle body -cleaned idle air control valve -fresh type IV transmission fluid -consistently using synthetic engine oil every 4-5000 miles Even by switching engine oil grade from 5w-30 to 10w-30, you'll feel the difference in idle vibration. The truth is the idle vibration can be improved but never be eliminated. It applies to Toyota/Lexus using the same 3.0L V6. Excessive vibration can be a sign of engine sludge, or partially blocked oil pickup screen. This will be the last thing we want to happen to our RX. My '99 RX300 has 90,000 miles on it. I, too, am experiencing increased vibration sound at idle, and I'm feeling more vibration in the steering wheel at idle. Hardened engine mounts would explain it. Is it safe to switch to synthetic oil after using conventional oil up until now? Quote Link to comment Share on other sites More sharing options...
lenore Posted March 9, 2006 Share Posted March 9, 2006 yes it is safe, I switched at 115k and it is doing great. Quote Link to comment Share on other sites More sharing options...
tmastres Posted March 9, 2006 Share Posted March 9, 2006 Ditto that , its definitely safe. If you're the worrying type you can do another oil change at 2k (or earlier) to be sure all the dino oil is gone but when I switched I didn't bother and I don't think there are any problems. With a 99 you should definitely be using Syn oil to avoid sludging. Quote Link to comment Share on other sites More sharing options...
chiks Posted March 29, 2006 Share Posted March 29, 2006 update: went to another dealer. He diagnosed bad IAC. replaced it. First impression. Vibration is there, but reduced than before. Quote Link to comment Share on other sites More sharing options...
tmastres Posted March 29, 2006 Share Posted March 29, 2006 update: went to another dealer. He diagnosed bad IAC. replaced it. First impression. Vibration is there, but reduced than before. Where is that on the RX and has anyone replaced it themselves? difficulty?? Thx! Quote Link to comment Share on other sites More sharing options...
bluestu Posted April 1, 2006 Author Share Posted April 1, 2006 update: went to another dealer. He diagnosed bad IAC. replaced it. First impression. Vibration is there, but reduced than before. How much did it cost to get your IAC replaced and did it make a big difference in the idle vibration? thanks. Quote Link to comment Share on other sites More sharing options...
GeneG2014 Posted February 12, 2014 Share Posted February 12, 2014 Hi, so did you guys figured where that annoying vibration comes from ? I'm experiencing the same thing on my '99 RX300 :whistles: Quote Link to comment Share on other sites More sharing options...
lenore Posted February 12, 2014 Share Posted February 12, 2014 read this thread: http://us.lexusownersclub.com/forums/topic/7408-iacv-location/?hl=iacv Quote Link to comment Share on other sites More sharing options...
james58 Posted February 10, 2023 Share Posted February 10, 2023 I HAVE THE SAME VIBRATION ON MY 2002 RX300. REPLACED MOTOR MOUNTS, IACV AND THRODLE BODY SENSOR, CLEANED THRODLE BODY ETC. ONLY WHEN THE CAR IS WARM, BUT IT DOES NOT DO THIS ALL THIME, SOME DAYS SMOOTH, OTHERS VIBRATES. REMINDES ME OF MY FRIST WIFE. CAR RUNS LIKE A TOP, NO CODES, ITS BUGGING THE CRAP OUT OF ME. 200K MILES AND THE CAR DID NOT DO THIS A YEAR AGO WHEN I GOT IT, JUST RECENTLY STARTED. HELP PLEASE Quote Link to comment Share on other sites More sharing options...
sps513 Posted February 20, 2023 Share Posted February 20, 2023 Good information and discussion, here. Thank to all for your posts. I have a '99 and it does the same thing. My dad bought it in 2001 or 2002 and says he always remembers it doing this. I do shift into neutral frequently when I come to a stop because the drone in the cabin is quite irritating, although I would not say I feel very much of a vibration. The vibration is only slight. Steve Quote Link to comment Share on other sites More sharing options...
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