LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

1998 ls400 problem -running rough P0172 code

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Old 02-10-15, 08:59 PM
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qewani1
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[QUOTE=almanai;8771532]
Originally Posted by Yamae
The air mix/assist path has 2 bigger holes and 8 smaller holes. After removing the lid unscrewing 2 Philips screws, clean all those holes especially 2 larger holes first spraying a can of cleaning solvent while your engine is idling to 1400 rpm (up and down). Don't rev too much. The engine rpm tends to drop and you need to control the throttle cable not to stop the engine also change the rpm between 750-1400rpm in order to change the condition.
What you mean ? Give me more an explanation? Please step by step
your engine is idling to 1400 rpm (up and down). Don't rev too much. The engine rpm tends to drop and you need to control the throttle cable not to stop the engine also change the rpm between 750-1400rpm in order to change the condition.

Should I stop the engine while cleaning the air mix path or clean it during engine is runing?

Should I take the throttle body out before i clean air mix path?

NOTE:- All 8 injectors are cleaned before one month ago .
Check the below post
Originally Posted by Yamae
Recently I just have helped a friend of mine who own a 98 Celsior which had a low idle problem and a strange acceleration problem when he turned a corner. I mean the car did not accelerate as if the AT was not engaged. As he pushed the gas pedal more, the car suddenly accelerated and this was rather dangerous.

Those two problems were completely gone after cleaning the throttle body and the air mix path. I took photos at that time and I show you them here below. The air mix path is located at top of the throttle body. The red arrow at top left photo shows the location of the air mix path. 2 photos at right side show it and the lid for it. As PD wrote at former post, the lid is held with two screws.

There are 2 bigger holes and 8 smaller holes at the air mix path. Clean all the holes using a engine conditioner or a carb. cleaner. You need almost a whole can to clean those 2 bigger holes. The air mix path is designed to supply the air to injectors aiming to get better gas mileage mixing the gas and the air at the injector. This path is very important both for the mileage and the smooth acceleration.

I must tell you 2 more that the cleaning of the air mix path should be done while the engine is idling. The throttle body has to be cleaned removing hoses and you also need to push the pre-throttle valve manually.

While cleaning the air mix path, keep car running and on Parking gear, when you feel that it will die, just increase the rpm by pulling the acceleratol cable connected to the throttle body
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