Vibration at idle while in gear
12-18-14, 06:23 AM
#16
Driver School Candidate
I had this same issue on my 2008 and 2012 in the winter. Are your headlights, seat warmer and AC off? If they are off and the rpm is about 500 you will feel the shudder. Try turning on one of the above and the rpm will go up to about 700 and with that the shudder goes away.
Is this caused by some kind of vacuum leak possibly or some other issue? I find it hard to believe that lexus would purposely program the rpm so low that it would cause vibrations.
12-18-14, 06:35 AM
#17
It sounds more like the electrical load is being detected by the engine ECU and its increasing the idle rpm slightly to compensate. Like I said before, the idle rpm can be increased but it's not a simple matter and many dealers will just tell you "can't be adjusted".
12-18-14, 07:42 AM
#18
12-18-14, 07:58 AM
#19
I asked before if the idle rpm can be changed and trustworthy shop foreman in a Lexus dealer told me that it is all computer controlled and they can't do anything. Again, leave your AC on, problem solved.
12-18-14, 08:55 AM
#20
Lexus Test Driver
12-18-14, 01:59 PM
#21
You hit it on the head. Today on the way to work, I turned off the heated seats and at idle I saw the rpm drop to about 475-500 rpm. The car started vibrating...I turned the heated seats back on and instantly the rpm goes to about 600 rpm and the car stops vibrating.
Is this caused by some kind of vacuum leak possibly or some other issue? I find it hard to believe that lexus would purposely program the rpm so low that it would cause vibrations.
Is this caused by some kind of vacuum leak possibly or some other issue? I find it hard to believe that lexus would purposely program the rpm so low that it would cause vibrations.
12-18-14, 02:20 PM
#22
Driver School Candidate
Per my Lexus service advisor Lexus engineers assumed that the AC would always be on. They believe that owners will set the temperature and the system will always run to keep it at that set temperature. The car was designed to idle at 700 rpm with the AC on. When you turn it off then the vibration starts. I now have a 2014 LWB and it has the same issue in winter if I turn the AC, headlights and seat warmer off.
12-19-14, 07:57 AM
#24
Not everyone.
I only turn on the A/C if I'm hot. I rarely run the seat heater. And I killed my DRL's. And at an idle, mine doesn't vibrate. I'm about to drive the car and I'll notice the rpm with it at idle with no seat heater, no A/C and no lights and report back.
I do these things because I'm very conservative and do not enjoy buying gasoline. One thing I do from time to time which is overkill but hey ... I'm riddled with various OCD issues, when the car is on "hold" and I'm going to be sitting there a while I bump it into neutral. The engine relaxes, its more quiet and comfortable, it idles away less fuel, and the hold feature continues to function. When I'm about to move again, I bump it into drive (still in hold mode) and the push the accelerator when ready. Never having touched the brake pedal during all that. I do this because I have always driven manual transmissions ... and having a car chugging trying to lurch ahead while I hold it back with the brakes feels unnatural after so many years driving a manual transmission.
I do these things because I'm very conservative and do not enjoy buying gasoline. One thing I do from time to time which is overkill but hey ... I'm riddled with various OCD issues, when the car is on "hold" and I'm going to be sitting there a while I bump it into neutral. The engine relaxes, its more quiet and comfortable, it idles away less fuel, and the hold feature continues to function. When I'm about to move again, I bump it into drive (still in hold mode) and the push the accelerator when ready. Never having touched the brake pedal during all that. I do this because I have always driven manual transmissions ... and having a car chugging trying to lurch ahead while I hold it back with the brakes feels unnatural after so many years driving a manual transmission.
12-19-14, 10:15 AM
#25
I do not have any excessive vibrations at idle. My transmission also shifts smooth as butter.
If I concentrate with everything off I can detect a very fine vibration at idle if I'm looking for it otherwise it feels as if the engine is off. Every car I have owned or driven including a Rolls Royce had this ever so minor vibration at idle. The German cars idle was more pronounced.
Just a theory but I believe the engine mounts are designed harmonically around the engine idle.
The idle is set differently for every engine type and it's probably an engineering efficiency calculation rather then one of smoothness.
If I had vibrations that were outside the norm the fist thing I would do is clean the MAF sensor as that usually solves many problems and if it doesn't it could be a MAF sensor that has drifted over time. The best way to know for sure is to hook up an ODB2 scanner and look at the live data for idle and note the frequency of dips. Also note the idle and compare it to the manufactures specs.
If I concentrate with everything off I can detect a very fine vibration at idle if I'm looking for it otherwise it feels as if the engine is off. Every car I have owned or driven including a Rolls Royce had this ever so minor vibration at idle. The German cars idle was more pronounced.
Just a theory but I believe the engine mounts are designed harmonically around the engine idle.
The idle is set differently for every engine type and it's probably an engineering efficiency calculation rather then one of smoothness.
If I had vibrations that were outside the norm the fist thing I would do is clean the MAF sensor as that usually solves many problems and if it doesn't it could be a MAF sensor that has drifted over time. The best way to know for sure is to hook up an ODB2 scanner and look at the live data for idle and note the frequency of dips. Also note the idle and compare it to the manufactures specs.
12-19-14, 07:38 PM
#26
Reporting Back...
I wish you turkeys had never brought this up. Ok, with no load on the engine, except the transmission, at a stop with it in D, it idles at about 450 rpm. When I bump it into neutral it idles maybe 700 rpm. I didn't specifically look but it was quite a bit higher. And yes, there's a very slight tremor at 450 rpm. I never noticed this before.
And when I bump it into neutral, it's smooth as glass, I can't even tell the engine is running.
Here's what I believe. The engine is set to idle at say 700 rpm. When it is placed in D and the brake is holding the car at a stop, the engine is still programmed to idle at 700 rpm, but it cannot achieve that with no throttle input because it's fighting the transmission. The ECU is not programmed to be aggressive at idle with no throttle input, because if it was it would cause the car to lurch unexpectedly or else the brakse would have to be held much more firmly.
My opinion, it's the engine, it's not balanced as well at 450 rpm as it is at 700 rpm. If you guys hadn't brought this up, I might have never noticed.
I also want to mention my 5.9L Cummins 6 cylinder is programmed VERY aggressively to hold idle speed. Sometimes when my wife is driving and she makes a sharp turn into something like a gas station. She'll have it in like 4th gear and uses the brakes alone to bring the speed down to turn into the entrance. Me knowing what's going on, i'm in the passenger seat cringing. She doesn't push the clutch in when it gets near idle, a pucker joins the cringe and I wind up pulling the leather seat covers out of my crack. And suddenly she's hauling **** into the entrance ... faster than she intended. She said to me before "these brakes are failing." And once I realize we've threaded the needle of other cars exiting, I roll my eyes and say, "honey ... the brakes are fine, you just gotta ... nevermind ... I'll check the brakes."
No amount of explaining would she understand. But what happens is that if say my truck is set for 700 rpm idle, it doesn't know if it's in gear or neutral, it's just tries to hold 700 rpm regardless. And even at idle it has huge torque, so it will pull the truck hard, and in her case it will feel like the brakes are failing. My wife drives a manual transmission well though. And she looks dern sexy driving my Dodge Cummins ... she's always getting honks and waves from other men when she's driving it.
7milesout
And when I bump it into neutral, it's smooth as glass, I can't even tell the engine is running.
Here's what I believe. The engine is set to idle at say 700 rpm. When it is placed in D and the brake is holding the car at a stop, the engine is still programmed to idle at 700 rpm, but it cannot achieve that with no throttle input because it's fighting the transmission. The ECU is not programmed to be aggressive at idle with no throttle input, because if it was it would cause the car to lurch unexpectedly or else the brakse would have to be held much more firmly.
My opinion, it's the engine, it's not balanced as well at 450 rpm as it is at 700 rpm. If you guys hadn't brought this up, I might have never noticed.
I also want to mention my 5.9L Cummins 6 cylinder is programmed VERY aggressively to hold idle speed. Sometimes when my wife is driving and she makes a sharp turn into something like a gas station. She'll have it in like 4th gear and uses the brakes alone to bring the speed down to turn into the entrance. Me knowing what's going on, i'm in the passenger seat cringing. She doesn't push the clutch in when it gets near idle, a pucker joins the cringe and I wind up pulling the leather seat covers out of my crack. And suddenly she's hauling **** into the entrance ... faster than she intended. She said to me before "these brakes are failing." And once I realize we've threaded the needle of other cars exiting, I roll my eyes and say, "honey ... the brakes are fine, you just gotta ... nevermind ... I'll check the brakes."
No amount of explaining would she understand. But what happens is that if say my truck is set for 700 rpm idle, it doesn't know if it's in gear or neutral, it's just tries to hold 700 rpm regardless. And even at idle it has huge torque, so it will pull the truck hard, and in her case it will feel like the brakes are failing. My wife drives a manual transmission well though. And she looks dern sexy driving my Dodge Cummins ... she's always getting honks and waves from other men when she's driving it.
7milesout
12-20-14, 04:29 PM
#27
Driver School Candidate
Thread Starter
I wish you turkeys had never brought this up. Ok, with no load on the engine, except the transmission, at a stop with it in D, it idles at about 450 rpm. When I bump it into neutral it idles maybe 700 rpm. I didn't specifically look but it was quite a bit higher. And yes, there's a very slight tremor at 450 rpm. I never noticed this before.
And when I bump it into neutral, it's smooth as glass, I can't even tell the engine is running.
Here's what I believe. The engine is set to idle at say 700 rpm. When it is placed in D and the brake is holding the car at a stop, the engine is still programmed to idle at 700 rpm, but it cannot achieve that with no throttle input because it's fighting the transmission. The ECU is not programmed to be aggressive at idle with no throttle input, because if it was it would cause the car to lurch unexpectedly or else the brakse would have to be held much more firmly.
My opinion, it's the engine, it's not balanced as well at 450 rpm as it is at 700 rpm. If you guys hadn't brought this up, I might have never noticed.
I also want to mention my 5.9L Cummins 6 cylinder is programmed VERY aggressively to hold idle speed. Sometimes when my wife is driving and she makes a sharp turn into something like a gas station. She'll have it in like 4th gear and uses the brakes alone to bring the speed down to turn into the entrance. Me knowing what's going on, i'm in the passenger seat cringing. She doesn't push the clutch in when it gets near idle, a pucker joins the cringe and I wind up pulling the leather seat covers out of my crack. And suddenly she's hauling **** into the entrance ... faster than she intended. She said to me before "these brakes are failing." And once I realize we've threaded the needle of other cars exiting, I roll my eyes and say, "honey ... the brakes are fine, you just gotta ... nevermind ... I'll check the brakes."
No amount of explaining would she understand. But what happens is that if say my truck is set for 700 rpm idle, it doesn't know if it's in gear or neutral, it's just tries to hold 700 rpm regardless. And even at idle it has huge torque, so it will pull the truck hard, and in her case it will feel like the brakes are failing. My wife drives a manual transmission well though. And she looks dern sexy driving my Dodge Cummins ... she's always getting honks and waves from other men when she's driving it.
7milesout
And when I bump it into neutral, it's smooth as glass, I can't even tell the engine is running.
Here's what I believe. The engine is set to idle at say 700 rpm. When it is placed in D and the brake is holding the car at a stop, the engine is still programmed to idle at 700 rpm, but it cannot achieve that with no throttle input because it's fighting the transmission. The ECU is not programmed to be aggressive at idle with no throttle input, because if it was it would cause the car to lurch unexpectedly or else the brakse would have to be held much more firmly.
My opinion, it's the engine, it's not balanced as well at 450 rpm as it is at 700 rpm. If you guys hadn't brought this up, I might have never noticed.
I also want to mention my 5.9L Cummins 6 cylinder is programmed VERY aggressively to hold idle speed. Sometimes when my wife is driving and she makes a sharp turn into something like a gas station. She'll have it in like 4th gear and uses the brakes alone to bring the speed down to turn into the entrance. Me knowing what's going on, i'm in the passenger seat cringing. She doesn't push the clutch in when it gets near idle, a pucker joins the cringe and I wind up pulling the leather seat covers out of my crack. And suddenly she's hauling **** into the entrance ... faster than she intended. She said to me before "these brakes are failing." And once I realize we've threaded the needle of other cars exiting, I roll my eyes and say, "honey ... the brakes are fine, you just gotta ... nevermind ... I'll check the brakes."
No amount of explaining would she understand. But what happens is that if say my truck is set for 700 rpm idle, it doesn't know if it's in gear or neutral, it's just tries to hold 700 rpm regardless. And even at idle it has huge torque, so it will pull the truck hard, and in her case it will feel like the brakes are failing. My wife drives a manual transmission well though. And she looks dern sexy driving my Dodge Cummins ... she's always getting honks and waves from other men when she's driving it.
7milesout
Last edited by vadpink; 12-20-14 at 04:45 PM.
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CamelKool (07-11-20)
12-20-14, 06:07 PM
#28
12-22-14, 10:04 AM
#29
This may not be exactly your problem, but on my LS 460, I had a rough idle which Techstream reported a a rare cylinder misfire. It would feel like the car was at a stop light next to a big truck. (Just a gentle rocking).
The dealer was able to replicate the cylinder misfires but noticed that the ECU was not properly saving error codes and so the 12V battery was diagnosed as being a problem. They replaced the battery and surprisingly, the rough idle disappeared.
If you look at these forums, it seems like the LS460 burns through its battery pretty quickly compared to other cars. It may be using more of the 12V DC battery for the electronics than other cars which power everything off the alternator once you get going.
I would try testing your battery and replacing it if it is worn.
The dealer was able to replicate the cylinder misfires but noticed that the ECU was not properly saving error codes and so the 12V battery was diagnosed as being a problem. They replaced the battery and surprisingly, the rough idle disappeared.
If you look at these forums, it seems like the LS460 burns through its battery pretty quickly compared to other cars. It may be using more of the 12V DC battery for the electronics than other cars which power everything off the alternator once you get going.
I would try testing your battery and replacing it if it is worn.
12-22-14, 03:58 PM
#30
Pole Position
Interesting stuff. I noticed my idle fluctuates between 500-700 at a stop light - after reading this thread I decided to shut my heated seats off - and sure enough the idle dropped right down to 500...and stayed there. I didn't realize the heaters drew that much current that the idle had to be raised to allow the alternator to spin faster.
I will say I don't really experience much, if any, vibration. The thing is smooth as butter. Now if only the wind noise would go away...
I will say I don't really experience much, if any, vibration. The thing is smooth as butter. Now if only the wind noise would go away...