Throttle body + MAF cleaning
04-06-10, 12:55 PM
#1
Instructor
Thread Starter
Throttle body + MAF cleaning
I've searched these forums for info about throttle body and MAF cleaning but I'm finding mixed answers applicable to the LS430. I think it would be great for everyone here if we could agree on some answers and create a step-by-step tutorial with pictures. EDIT: I've performed the throttle body cleaning today (Jun.4/2010). Here are the instructions:
Open hood
Remove MAF connector (one clip at the top of the air filter box)
Remove the rigid plastic tube on the back of the air filter box (2 Phillips screws)
Loosen the metal clamp connector the airbox to the intake tube (1 big Phillips screw)
Pop the 4 clips holding the top of the airbox on.
Remove the top of the airbox by gentling pulling and rotating the box away from the air intake tube.
Next, remove the air intake tube and the box connected to it. There is one 12mm bolt on the passenger side holding it down and a metal clamp on the throttle body end of the intake tube. Remove the bolt and loosen the clamp, then the whole thing comes off with gentle pulling and rotating.
Once the air intake tube is removed, you can see the throttle body. You can clean one side of it now, but for a more thorough job, you can remove the 4 12mm bolts and pull the throttle body away from the engine. The throttle body is connected to 3 tubes. I was not able to safely remove these tubes, so I left them connected. I was able to work on both sides of the throttle body by pulling it off of the top 2 guide rods and leaving it hanging nearby.
Be careful not to let any dirt/dust particles enter the engine.
Once you can access both sides of the throttle body, you can dampen lint-free cloth with 99% isopropyl alcohol and wipe away both sides of the throttle body plate and the inside of the body.
DO NOT push the plate with your finger to open it up - this can throw off the calibration of the throttle position sensor and/or throttle body motor. Instead, turn IG=ON, engine OFF, and put a brick on the accelerator pedal. This will let you clean the edges of the plate and the sides of the body. Clean away until no black appears on your cloth.
For good measure, I vacuumed the entire area after I was done, before reinstalling the throttle body.
Car did not have much or any rough idle before. The idle is smooth for sure now. I may be imagining things but I think the idle is slightly higher than before. OEM spec for idle is 750+-50 rpm. I'll try a battery pull to reset the ECU.
1) The Lexus repair manual says the throttle body gasket is non-reusable. Did anyone here ever reuse this gasket? What is the gasket's part number? EDIT: I reused the gasket.
2) Throttle body cleaner, carb cleaner. brake cleaner, electronic contact cleaner have all been both recommended and disapproved for throttle body and/or MAF cleaning. What is your take? EDIT: I used 99% isopropyl alcohol.
3) Do you need to clean both sides of the throttle body flap or just intake side? EDIT: I cleaned both sides of the flap and the inside of the body. Removing those 4 bolts is not that much more work to clean both sides.
4) How much should the flap be left open or closed? I'd think you'd leave it the way you found it, which is likely fully closed. https://www.clublexus.com/forums/5141304-post21.html EDIT: The flap closes by itself..
5) Does anyone already have step-by-step pictures for this? EDIT: Sorry, did not take pictures because I didn't know what I was doing. Just took things apart until I got to it.
What are your thoughts on the quotes below?
6)
7)
EDIT: I removed the MAF and examined the wires, did not see much buildup. Undecided if cleaning it would be safe.
8)
EDIT: The flap moves just fine on the 2002, just disconnect the 2 main electrical harnesses before playing with it.
9)
EDIT: I used 99% alcohol, do not see how it will affect the electrical system.
Open hood
Remove MAF connector (one clip at the top of the air filter box)
Remove the rigid plastic tube on the back of the air filter box (2 Phillips screws)
Loosen the metal clamp connector the airbox to the intake tube (1 big Phillips screw)
Pop the 4 clips holding the top of the airbox on.
Remove the top of the airbox by gentling pulling and rotating the box away from the air intake tube.
Next, remove the air intake tube and the box connected to it. There is one 12mm bolt on the passenger side holding it down and a metal clamp on the throttle body end of the intake tube. Remove the bolt and loosen the clamp, then the whole thing comes off with gentle pulling and rotating.
Once the air intake tube is removed, you can see the throttle body. You can clean one side of it now, but for a more thorough job, you can remove the 4 12mm bolts and pull the throttle body away from the engine. The throttle body is connected to 3 tubes. I was not able to safely remove these tubes, so I left them connected. I was able to work on both sides of the throttle body by pulling it off of the top 2 guide rods and leaving it hanging nearby.
Be careful not to let any dirt/dust particles enter the engine.
Once you can access both sides of the throttle body, you can dampen lint-free cloth with 99% isopropyl alcohol and wipe away both sides of the throttle body plate and the inside of the body.
DO NOT push the plate with your finger to open it up - this can throw off the calibration of the throttle position sensor and/or throttle body motor. Instead, turn IG=ON, engine OFF, and put a brick on the accelerator pedal. This will let you clean the edges of the plate and the sides of the body. Clean away until no black appears on your cloth.
For good measure, I vacuumed the entire area after I was done, before reinstalling the throttle body.
Car did not have much or any rough idle before. The idle is smooth for sure now. I may be imagining things but I think the idle is slightly higher than before. OEM spec for idle is 750+-50 rpm. I'll try a battery pull to reset the ECU.
1) The Lexus repair manual says the throttle body gasket is non-reusable. Did anyone here ever reuse this gasket? What is the gasket's part number? EDIT: I reused the gasket.
2) Throttle body cleaner, carb cleaner. brake cleaner, electronic contact cleaner have all been both recommended and disapproved for throttle body and/or MAF cleaning. What is your take? EDIT: I used 99% isopropyl alcohol.
3) Do you need to clean both sides of the throttle body flap or just intake side? EDIT: I cleaned both sides of the flap and the inside of the body. Removing those 4 bolts is not that much more work to clean both sides.
4) How much should the flap be left open or closed? I'd think you'd leave it the way you found it, which is likely fully closed. https://www.clublexus.com/forums/5141304-post21.html EDIT: The flap closes by itself..
5) Does anyone already have step-by-step pictures for this? EDIT: Sorry, did not take pictures because I didn't know what I was doing. Just took things apart until I got to it.
What are your thoughts on the quotes below?
6)
I know there are TONS of threads on this topic but all mention DO NOT spray throttle body cleaner down the TB throat as it could cause damage. I have read in many places that this ONLY stands true for drive-by-wire throttle systems due to potential damage to sensors in there.
8)
9)
Cars with Electronic Throttle Control (Drive-by-wire) should not be cleaned with any types solvents at all. You will mess up the electrical system and will cause the car to go into limp mode as it runs rough as stated above. I believe the best way to clean it would be just wipe it clean with a clean rag and that's it.
Last edited by StanVanDam; 08-20-19 at 12:20 PM. Reason: Performed throttle body cleaning, added details.
04-06-10, 08:08 PM
#2
I clean the TB on my LX using carb cleaner. Do not spray it directly into the TB since there's a sensor in there (on the LX, it's at 12 o'clock). I sprayed some cleaner on a small stainless brush and gently swabbed out the carbon around the front flap. To do this, I just removed the hose from the air cleaner to the TB. Use a rag and wipe up any excess. It's only in the older cars like 1980's toyotas where you can spray carb cleaner directly into the TB since there are no sensors. You can press in the flap a little to get around the edges. You should clean the flap area about every 30K mi to remove carbon buildup. Otherwise, when there's enough buildup, the flap gets stuck. On an old car, you'd feel the accelerator stick from the flap being stuck shut, but on new cars, there's a motor that opens the flap. If there's enough buildup, the motor isn't able to open the flap and, guess what? You'll get a "check engine" code saying the TB is bad. Dealer will only replace the TB for around $700. Even if you get the code, you can still clean up the TB flap, reset the code or unplug the battery, and you're likely good to go.
04-06-10, 10:15 PM
#3
I clean the TB on my LX using carb cleaner. Do not spray it directly into the TB since there's a sensor in there (on the LX, it's at 12 o'clock). I sprayed some cleaner on a small stainless brush and gently swabbed out the carbon around the front flap. To do this, I just removed the hose from the air cleaner to the TB. Use a rag and wipe up any excess. It's only in the older cars like 1980's toyotas where you can spray carb cleaner directly into the TB since there are no sensors. You can press in the flap a little to get around the edges. You should clean the flap area about every 30K mi to remove carbon buildup. Otherwise, when there's enough buildup, the flap gets stuck. On an old car, you'd feel the accelerator stick from the flap being stuck shut, but on new cars, there's a motor that opens the flap. If there's enough buildup, the motor isn't able to open the flap and, guess what? You'll get a "check engine" code saying the TB is bad. Dealer will only replace the TB for around $700. Even if you get the code, you can still clean up the TB flap, reset the code or unplug the battery, and you're likely good to go.
09-04-10, 08:56 AM
#6
Did mine last weekend. The hesitation that I experienced on acceleration has diminished. The car being on cruise without engaging cruise no longer happens. Has anyone tried seafoam?
12-15-12, 12:42 PM
#7
Driver School Candidate
Trending Topics
12-16-12, 03:10 PM
#8
Sea Foam is the best cleaner that I have found in 30 years of being a technician.
Allow me to clear up a few myths about cleaning the throttle body plate. You cannot damage anything inside the intake manifold by spraying cleaner inside. All the manifold does is basically carry air from the throttle body into each cylinder. Take a flashlight and look inside the manifold and you will see just about nothing but black, oily film and that's about it.
This is how about 95% of the Lexus technicians clean a TB.
Remove the air intake plenum. Take a lint free cloth and put it on the bottom of the TB which will leave the plate open enough for you to clean the top half of the TB and plate. Remove cloth and hold plate open to clean the bottom half. We all use a toothbrush and carb cleaner. I like to spray the TB with Sea Foam and allot it to set for about 5 minutes. The carbon comes off much easier without having to use a brush. I just spray it with carb cleaner real good and it's good to go.
Currently Ford is the only manufacture that states to not use carb cleaner on the throttle body. They apply some type of coating the outer edges of the TB plate and cleaner will remove it.
Allow me to clear up a few myths about cleaning the throttle body plate. You cannot damage anything inside the intake manifold by spraying cleaner inside. All the manifold does is basically carry air from the throttle body into each cylinder. Take a flashlight and look inside the manifold and you will see just about nothing but black, oily film and that's about it.
This is how about 95% of the Lexus technicians clean a TB.
Remove the air intake plenum. Take a lint free cloth and put it on the bottom of the TB which will leave the plate open enough for you to clean the top half of the TB and plate. Remove cloth and hold plate open to clean the bottom half. We all use a toothbrush and carb cleaner. I like to spray the TB with Sea Foam and allot it to set for about 5 minutes. The carbon comes off much easier without having to use a brush. I just spray it with carb cleaner real good and it's good to go.
Currently Ford is the only manufacture that states to not use carb cleaner on the throttle body. They apply some type of coating the outer edges of the TB plate and cleaner will remove it.
12-17-12, 05:05 PM
#9
Getting to the throttle body is pretty straight forward if you are even slight mechanically inclined. I took mine off to clean it better and it drives so much smoother and the acceleration is better. I reused the old gaskets, etc too. I had no problems reusing them, as long as you put everything back correctly qnd everything if torqued back. I idle at about 500 after warmed up now. Like the person above me, I cleaned it with carb cleaner and used a toothbrush and towel to clean it up good. This was a good investment of time, now my baby is running smoother than ever!
12-18-12, 01:08 AM
#10
Pole Position
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I took the complete MAF out and put it in the plastic container with ethyl alcohol and shook it well...lot of dirt came out of it and I cleaned the resistors (sensors) with earbuds until they were like new...from black to metal shiny
Idle changed slightly, but all is still ok and well...did it mostly as preventative measures
Idle changed slightly, but all is still ok and well...did it mostly as preventative measures
08-18-19, 09:57 PM
#13
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StanVanDam (07-03-21)
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