When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I thought I would start a maintenance thread on throttle body and MAF cleaning.
I'll edit this in to a more cohesive post as maintenance is done or adding more info.
I plan to pick this up and I imagine things have to be really...really bad to gain 4-10 HP at the rear wheels. :-)
You will see some videos on Youtube that Toyota/Lexus motors will go into a high idle state after a throttle body cleaning as they are now passing more air and need to adjust. The FSM states you can just pull the EFI fuse to speed this up. I'll post where that is later.
Not really that much disassembly to do this.
[MAF location]
[MAF Removal]
[MAF Cleaning]: IMO I would not touch any wires and use the CRC MAF spray above to clean dirty sensor wires. If any instructions on CRC can are different I will update.
========================================
[Throttle Body Location]
[Throttle Body Check with Techstream] - I would only go down this troubleshooting if I suspected a problem.
[Removing items to access Throttle body] - I don't plan to remove throttle body but to clean in place. Some remove completely. I do not plan to do that.
[Clean throttle body with CRC cleaner] - I am told throttle plate can be actuated for cleaning as long as vehicle is completely powered off. Clean in place and don't remove screws in picture below.
Noticed the slightest of a rough idle so thought I would do a MAF and Throttle Body cleaning. It was very dirty and it seems to have smoothed idle out noticeably.
RPM after cleaning was a little high but expected this as vehicle adjusts to more airflow from cleaning. I wouldn't call what I did the most comprehensive cleaning but I was able to get all the dirty areas around throttle plate and throttle plate edges cleaned with some q-tips with wooden handles and some TB spray. RPM settled after a few minutes.
I gave the MAF sensor a few shots of MAF cleaner as well.
I didn't want to risk messing up the throttle adjustment so after I had removed everything needed I plugged the MAF back, turned vehicle on and placed a heavy object to floor the accelerator in a non-running vehicle. This opened the throttle fully. I applied no significant pressure to the throttle plate while cleaning. The TB solution seems to break through the residue/grease fairly easily.
Some day I need to take some video how Pedal Commander influences throttle opening versus stock.
Just did this also and noticed a smoother idle and acceleration. Before I used to get this tiny vibration in the pedal at 40-50% throttle 1.5K-2K RPM. It’s still there but much less. I hooked up my OBD2 reader to monitor before and after and it seems to help returning my LTFT to normal a bit (before part throttle +9%, after cleaning 6%) and fuel economy improved ~0.5 mpg. As Acrad mentioned, plug in the MAF before turning on accessories or the ECU will throw a permanent code for not detecting the MAF (air intake temp hi OOS and MAF reading high OOS). When the throttle pedal is pushed all the way down the throttle plate opens about 90 degrees from open. There’s a distinct catch noise when the plate comes closed against the caked up throttle body. It’s gone now once it’s cleaned.
You guys ever thought about doing a catch can? It would pretty much eliminate this oil going through the intake. I bet having the intake manifold extrude honed would make nice improvement. Someone did this on their LS and claimed 10 HP and better mileage under normal cruising conditions
You guys ever thought about doing a catch can? It would pretty much eliminate this oil going through the intake. I bet having the intake manifold extrude honed would make nice improvement. Someone did this on their LS and claimed 10 HP and better mileage under normal cruising conditions
I've installed aftermarket catch cans on various other toyotas over the years including 4runners and opted against it on the gx460. While it does remove oil from the intake manifold via the Pcv exhaust, the benefit to engine longevity or performance was not quantifiable compared to running a complete fuel system cleaner every oil change... plus it kinda voids the engine warranty if something were to break with the install... since theres no major engine issues with the gx460 outside of the timing cover which is never catastrophic, no point creating one.. if I want better than 20mpg fuel efficiency I'll buy a rivian.
Could you have the ignition ON and have someone press the gas pedal to open the throttle plate without having to manually do it? As long as the vehicle isn't running, this should work, right?
Could you have the ignition ON and have someone press the gas pedal to open the throttle plate without having to manually do it? As long as the vehicle isn't running, this should work, right?
That is how I cleaned mine... I had a board that depressed accelerator to the floor while the vehicle was not running but turned On. Throttle plate opened up for me to clean.
That is how I cleaned mine... I had a board that depressed accelerator to the floor while the vehicle was not running but turned On. Throttle plate opened up for me to clean.
Had I read your original post more carefully, I would have seen that!
Good info and a good thread, going to order the cleaner and do my GX, which is at about 125k now. Will update here once I have completed it.
The TB plate usually has some sort of grease or lubricant where connects to the body and it is recommended to avoid those areas. Did you see anything on the Lexus TB?
Just completed this on my GX460 and did the MAF on my LS430 and my ES330.
For the GX, mine didn't seem to be too dirty, and it cleaned up pretty quickly. I had my son sit in the car with his foot on the gas to open the throttle plate. When I went to restart it after putting it back together, I did get an extended crank before the engine finally caught and I had a CEL once it was running. The car had a P0102 for the MAF, so I cleared the code and it didn't come back. Numerous subsequent restarts resulted in the usual starting method, so I'm not sure why it cranked so much on the first time. Maybe I sprayed too much MAF cleaner or didn't let it dry out enough first.
I did notice while monitoring the TPS, that at idle, it's at 17 and at full throttle, it only goes to 82 (maybe 86... I don't recall). I'm sure that's normal but still seems a bit odd. Oh well, finished the job with a fresh Denso air filter. Last one was only two years and about 15k on it, seemed fine but they are so cheap, why not? Oh, the clip that holds the MAF harness to the airbox also broke on me, chalk it up to brittle plastic.
Both of these are before pictures...
And come to think of it, I believe my GX had the throttle body replaced at about 70k. I'll have to look at the Lexus Drivers site again, so that might have something to do with why it was so clean at 125k.
Went and looked;
SERVICE: CHECK ENGINE LIGHT ON
DESCRIPTION: CHECK ENGINE LIGHT ON ~|~CHECK ENGINE LIGHT ON ~|~ ~|~72176 AFTER TIMING COVER REPAIR CHECK ENGINE LIGHT WAS ON, CODE P2111, THROTTLE CONTROL ACTUATOR STUCK OPEN, REPLACED THROTTLE BODY ASSEMBLY
Got the timing cover and the throttle body replaced, would have been under CPO warranty for the previous owner. That was an expensive repair though.
That looks pretty clean. I'll need to do gather some TPS stats on mine. At some point I wanted to see & cam capture what effect Pedal Commander had on throttle body opening. Stock programming in another make of mine showed a muting of throttle on a pedal mash. I want to see if there are any differences between PD installed and not.
10-27-18, 05:41 PM
Throttle Body and MAF cleaning
