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I have the same problem.
I've been repairing it for one year. I I Want to cry,
I noticed something annoying on my 05 LS430, The RPM rate drops to around 500 when I set the transmission to "D" along with a slight vibration and strangely. If i change that to P, N. or even Reverse. It jumps back to 750 normally. Above numbers are while no AC/Headlights on. If i turn on the AC, the headlights or the seat heater. those 500 jumps to 750.
What I tried so far:
PCV valve
Replace ECU Spark Plugs
All cleaning（Fuel injection，Intake valve，Intake pipe..fuel pump,）
AIR CONTROL VALVE
I've tasted almost everything....
Check to make sure you have no vac leak, clean everything, test the TB and sensors to make sure they are within range, then do a throttle calibration and TPS relearn.
Check to make sure you have no vac leak, clean everything, test the TB and sensors to make sure they are within range, then do a throttle calibration and TPS relearn.
Fixed mine back back when I first got it
Thank you for your reply. I've done everything you said
I think it could be vac leak..But I can't find where it is.
I bought this, but I didn't find vac leak.
My car also idles "low" in D, engine warm, no AC. around 450-500 rpm but the engine and car are completely smooth, no vibrations. I think this is normal. If you are concerned about the vibrations, you might want to investigate the health of your transmission mount or motor mounts. There should be no noticeable vibration and is quite possible the mounts are the problem not the idle RPM.
Toyota UZ engine series are known to fail to control the idle speed when both the throttle body and air mix passages are badly clogged. It is very important to clean the air mix path using a can of carbon solvent with an air compressor when the engine is warm. This has to be done too when you clean the throttle body. As is shown in the drawings below, the passage starts at the throttle body and reaches to each injectors. I found many old UZ engines failed having
the line was blocked by carbon deposits and the ECU can't control the idle speed well because of out of control range.
An injector's lower end is like this below and the air from the throttle body goes to the cylinder via the air mix path. When the air is blocked by carbon deposits, the idle speed becomes lower and also the AT shift often becomes strange too.
[QUOTE=Yamae;Toyota UZ engine series are known to fail to control the idle speed when both the throttle body and air mix passages are badly clogged. It is very important to clean the air mix path using a can of carbon solvent with an air compressor when the engine is warm. This has to be done too when you clean the throttle body. As is shown in the drawings below, the passage starts at the throttle body and reaches to each injectors. I found many old UZ engines failed having
the line was blocked by carbon deposits and the ECU can't control the idle speed well because of out of control range.
An injector's lower end is like this below and the air from the throttle body goes to the cylinder via the air mix path. When the air is blocked by carbon deposits, the idle speed becomes lower and also the AT shift often becomes strange too.
[/ QUOTE]
Thank you. You gave me new hope. I cleaned the intake manifold once, and then these problems occurred . Sonicleaning
Toyota UZ engine series are known to fail to control the idle speed when both the throttle body and air mix passages are badly clogged. It is very important to clean the air mix path using a can of carbon solvent with an air compressor when the engine is warm. This has to be done too when you clean the throttle body. As is shown in the drawings below, the passage starts at the throttle body and reaches to each injectors. I found many old UZ engines failed having
the line was blocked by carbon deposits and the ECU can't control the idle speed well because of out of control range.
An injector's lower end is like this below and the air from the throttle body goes to the cylinder via the air mix path. When the air is blocked by carbon deposits, the idle speed becomes lower and also the AT shift often becomes strange too.
Yes. Those two holes are so. But remember those two are connecting to this block below which is attached to the throttle body. Through 8 small holes the air is coming in and goes to two larger holes that are connected to two holes you showed. You can access those 8 smaller holes and 2 larger holes just removing the lid unscrewing 2 + screws. This block is often badly clogged and in that case, two larger holes connected to each injectors are also clogged. Cleaning all of these will help the engine run good as well as to improve the gas mileage.
Yes. Those two holes are so. But remember those two are connecting to this block below which is attached to the throttle body. Through 8 small holes the air is coming in and goes to two larger holes that are connected to two holes you showed. You can access those 8 smaller holes and 2 larger holes just removing the lid unscrewing 2 + screws. This block is often badly clogged and in that case, two larger holes connected to each injectors are also clogged. Cleaning all of these will help the engine run good as well as to improve the gas mileage.
Yes, I opened and cleaned. It's blocked. I'll clean the channel. Thank you again
Yes, I opened and cleaned. It's blocked. I'll clean the channel. Thank you again
You are welcome. You probably need an air compressor to clean thoroughly. Badly clogged air mix passages can't be cleaned only by using a spray can of carbon cleaner. Spray and blow with a compressed air up to 2kg/square cm using an air compressor. Don't blow stronger than that to avoid the damage of injector's air outlets. It would be also better to do this removing spark plugs aiming cylinders to keep the pressure 1atm. So that the compressed air can goes out of cylinders easier. Hope your success.
You are welcome. You probably need an air compressor to clean thoroughly. Badly clogged air mix passages can't be cleaned only by using a spray can of carbon cleaner. Spray and blow with a compressed air up to 2kg/square cm using an air compressor. Don't blow stronger than that to avoid the damage of injector's air outlets. It would be also better to do this removing spark plugs aiming cylinders to keep the pressure 1atm. So that the compressed air can goes out of cylinders easier. Hope your success.
10-23-21, 02:36 AM
Low idle （400RPM） while on Drive - Lexus LS430
