Hello guys I have a 2006 Lexus gs430. I’ve had a vibration at idle for a while and I changed the engine mounts and transmission mounts yet it didn’t help. It only vibrates/misfires in D or R while stopped when I start driving I don’t feel it. And when I put the car in N or P it idles normal. When it’s in D or R and idling it idles at 550rpm which I don’t think is normal. But when put it in P or N the idle returns to 650rpm which should be the normal idle. I’ve driven around with this issue for a while because the check engine light would only pop up when I would leave it in D when I came to stops. (I always put it in N because the vibration is bothering). First time it popped up it read misfire cylinder 4. So I changed all spark plugs and coil packs (OEM). But the issue was still there. (The check engine light pops up if you don’t put it in N for multiple stops). So I just decided to not dig deeper and just kept putting the car in N when coming to all stops. But I eventually got tired of putting it in N and starting leaving it in D at stops. And sure enough the check engine came on again. After a week of not putting it in N at stops I came to one stop and was sitting there for about 2 minutes and the check engine light started flashing. I put the car in N and after 4 seconds it stopped flashing. Now I’m just tired of the issue and want to get over it and fix it. I’m thinking it’s some type of idle sensor but not really sure and hoping it’s not something big. I want to try and fix it myself before I take it to a mechanic. Also every time the check engine light shows up it says check VSC aswell. Sorry if I explained it bad this is the first time I’ve written on a forum. Please feel free to ask any questions. I’ve attached pictures of the check engine and check VSC.

Every time the check engine and check VSC light turn on it also turns off the traction control.

 

Have you tried scanning the engine codes? If not go take it to get the codes scanned.

Also when you replaced the plugs and coils you stated you purchased oem. Did you buy them from the dealer or from another place. Because there are a lot of fake oem plugs floating around.

when was the last time you clean the throttle body, and did a combustion cleaning? Its possible you may have some carbon building inside.

Another possibility, it could the transmission convertor chattering. When was the last time you replace the transmission fluid?

 

yes the spark plugs and coil packs were directly from the dealer. And I did do a throttle body cleaning a when I changed the spark plugs and coil packs. But I have not done a combustion cleaning. How exactly does a combustion cleaning work?

 

After you replaced the plugs and coils, did you rescan the engine codes? Was the #4 cylinder still present?

If that same code popped back up and the code is the same on the cylinder then I would look at the wiring plug on that coil. Remove it, make sure the pins are intact, make sure the wires to it are not damaged. Its possible a rodent chewed a wire! What you can do is when the car is idling low, play with the connection on #4 remove the plug while the engine is running, if theres no change or the engine suddenly raises the rpms then its more likely a connection issue.

 

also check your #4 injector if the code still come up with misfire number 4.

 

You might have 2 totally different problems or one problem disguising as another problem.
When engine misfires, engine will shake abnormally.

In parked position, rev the engine to 2K to 3K RPM really quick and have someone what your engine with the engine cover off, or better yet record the video with you phone.
And then see if the engine jerks abnormally.

If misfiring is only occurring while idling in R or D and RPM drops to 550, I highly suspect TB, though you said you cleaned it.
The electronic TB has a motor that controls how wide to open or close the internal (round) plate, and dual TB plate position sensor.

If you are able to accelerate and reduce speed normally and smoothly during driving without any misfiring, then the TB motor is likely good,
However, if the TB plate position sensor gets a bad reading, that'll definitely mess up the smooth idle and cause misfire.
Replacing plugs and ignition coils for this type of problem will not help at all.

Usually bad throttle position reading leads to random misfire, versus consistent misfire on a particular cylinder.
Do get an ODBII reader if you don't have one, and check closely on which code P030x you get consistently.

Bad plug and/or ignition coil combo for a cylinder likely will trigger misfire during driving as well.

The fact that it's only during idle in R & D, I would check the voltage on the throttle position sensor.
There are number of YouTube videos on how to do this.

Also, the Lexus and Toyota connectors are notorious for literally falling apart when they are 10+ years old.
I know this, because I broke nearly ten of them, while removing the intake manifold and plenum covers to clean the intake valve carbon build up.
And one of ones that broke was the TB connector. So disconnect the TB connection and check for connector pins very carefully.

Here is a video of many connectors getting replaced, including the TB connector.

While at it, also clean and check the MAF (Mass Airflow sensor) connector and test the voltage as well.
Bad/dirty MAF can also distort how much air is coming in, and cause ECU to miscalculate optimal fuel/air ratio,
and trigger rough idle.