Mrfix

Just curious whether diconnecting the battery but keeping the ECU alive would introduce any issues? I have the following device ( http://a.co/76Nfb0I ) I use when disconnecting the battery but was unsure if the ECU needs to be dead so it isn't sending info to the servo on the TB or anything. I understand that once it is disconnected from the vehicle the butterfly can be moved and should return to the rest position. I just don't want to lose all my other settings in the car.

Jeeves250

I cleaned mine the other week when I was doing spark plugs; I had the battery disconnected, and opened the throttle butterfly by hand, and kept it open with a plastic screwdriver handle, and that worked well while I was cleaning it. Re-connected the battery once I was done, and had zero problems.

The only settings that were lost were the "tank average" reading in the dash computer, and which radio input I'd had selected (it defaults to FM 1, I think.) Apart from that, everything else was fine.

2013FSport

iTrader: (2)

No need to undo the battery for TPS or MAF disconnect as long as you you give it 4min or so to do its shut down process after the ignition is off. It does turn that stuff off...

StanleyR

Any improvement after cleaning the TB?
I have a new can of TB cleaner that I was thinking of trying it on this car. It doesn't have any idle problems, so maybe I should leave well enough alone?

Mrfix

Thanks guys, will be cleaning the TB this weekend. I really don't know if it even needs it but I don't think it's been cleaned yet (car has 94k on it). It basically was running really smooth and I notice just the slightest (really, really faint) little roughness when it's idling at a stop sign or red light. I have some MAF cleaner so I might as well give that a blast too. I probably not keep the ECU alive while I disconnect the battery and remove the TB to give it a good cleaning.

StanleyR

I notice the same on my is350. But I also realized that it seems consistent with the amount of fuel I have in the tank.
As long as it's over 1/2, I don't notice the faint roughness.
As a result, I simply resorted to keeping the tank over 1/2 at all times. It's also cheaper to fill from half as prem. gas is about 1.80 here in Vancouver BC

2013FSport

iTrader: (2)

Word of warning, do not use metal or hard plastic to prop the butterfly open. The edge can easily be nicked and damaged. You will notice it's pretty sharp too.

Take a couple pictures of that mesh screen thing too. I'm curious if it can be removed.

This is at 58,000 mi...

Jeff Lange

iTrader: (1)

The metal screen is part of the throttle body gasket. It could likely be removed, but I don't think there would really be any reason to do so.


Jeff

Gville350

iTrader: (10)

First TB gasket I've ever seen with a grill to it! LOL!

2013FSport

iTrader: (2)

It keeps the whole rodent from being ingested!

And maybe small tools!

Jeeves250

Mine wasn't extremely dirty, so I didn't notice any difference. It's good to stay on top of throttle body cleaning, just like it is good to change your air filter from time to time: every little bit helps the car run as it was intended to do.

A dirty throttle body, left alone for long enough, will stick, and/or let excess air through by not closing properly. The worst that can likely happen is high or rough idle, and crap throttle response.

It's not going to seem like you're doing much by cleaning it, but it's necessary, and is part of a healthy service regimen for any car.

kleepytime

Hi

So sorry for necro but the subject is the same so I guess it doesn't matter.

I cleaned my 2008 IS350's throttle body near the end of last month (about 2 weeks ago).
(I had test-drove a number of IS 350 before purchasing this one about 3 months ago, and found that there is a difference in throttle response and "stickiness" and one of the car dealer's service technicians suggested that they clean the throttle bodies to correct that)

I've been very happy with my Lexus and it has been excellent in almost every respect; and idles well and runs great, however on inital tip-in it's hard to tip-in smoothly it will jump off the line if you're not very very careful.

So I purchased some fresh throttle body/ carb cleaner and have a number of tools on hand.

I pulled the rubber intake intake hose (10mm screw clamp on each end), and the breather and brake-booster hoses (long-nose pliers).

With a rubber handled ratchet (and/or my fingers) I was able to keep the throttle plate open; the plate itself looked approximately like 2013FSport's picture above.
Around 0.5 to 1mm of carbon gunk on the edge of the plate
I sprayed some cleaner on paper towels and clean rags, then wiped off the gunk until the towel/rags came clean.
The back edge of the plate is much harder to get, I used a pick to push a cotton rag around the back and then sprayed some cleaner on the rag and pulled it back and forth as best I could, I also used an old toothbrush to reach around the edge (with carb-cleaner on it.)

After cleaning I put the car back together, and I DID NOT disconnect the battery.

Starting the car it idles around 1500rpm... not 750 as before...
After a bit of self-adjustment it seems to settle around 1050 to 1200rpm.

I then searched high and low and tried several "re-learn" procedures for Toyota/Lexus but they had no effect.
There were some threads that suggested just simply drive it around it will self adjust.
I drove around quite a bit over several full warm-up cycles. It still idled at 1100 ish
Also at low speed it would sometimes hunt for a higher idle which could be disconcerting when trying to park for example

Today I pulled it apart again thinking perhaps I missed a bit of carbon on the back edge of the plate that was holding it open enough to idle wrong.
It was actually clean.

So I disconnected the battery for 5 minutes or thereabouts.

Reconnected;

Worryingly the start button did not immediately go green when the brake pedal is depressed initially, however after 30 seconds or so of pressing the button and braking and fiddling it did turn on.
The first start was very slow it cranked for about 2 or 4 seconds or so.
After cranking the idle was high but dropping smoothly
I then had to lower each window from the button *on it's actual door* and then hold the up button until it was closed, which resets the window sensors.
Reset the clock, time-zone, and a few other minor settings.
By this time the idle had dropped to it's normal 750-800 ish.

Fantastic.

TLDR; I did have to disconnect battery to reset a high-idle-speed condition after throttle body cleaning

primavera

This past summer I replaced the spark plugs, cleaned throttle body, MAF sensor and replaced the PCV valve.
After driving it for a while with the new plugs in I've noticed the RPMs were just a little bit higher (around 800~900 rpms)
Didn't think of it too much back then, but now that the winter is here and temperatures dipped below 0 C the idle wants to stay high 1800~2000 rpm on the first start in the morning and won't drop below 1000 even when the engine reaches operating temp. Checked the coolant and it showed normal level between max and low.

Cleaning throttle body can mess up the internal settings and it needs to be reset to stabilize the RPMs .
I just did this on my car, now the RPMs are at 600!!!

Here's how to reset throttle body and smooth out the high idle.

Written instructions in case Fact Checkers take the video down


Warm up the engine before doing the reset!

IGNITION ON
IGNITION OFF

IGNITION ON
FOOT ON BRAKES, START THE ENGINE, PUT THE GEAR IN DRIVE "D"
HOLD FOOT ON BRAKES, LET THE ENGINE RUN FOR 5 MIN....

PUT THE GEAR IN NEUTRAL "N"
SHUT OFF THE ENGINE.

PUT THE GEAR IN PARK "P"

START THE CAR


Voila, enjoy the smooth running car.

MikeFig82

iTrader: (13)

I did this once long ago on my IS250. If I recall you can see the needle move ever so slightly. Though here in HTX the temps rarely get below 30. I've never had an issue with high RPM's since owning the car. Even after cleaning the TB.

I'll try it out on my GS350 tonight before leving work. Just to let it warm up, and kill some time.

I would actually like to see the service manual. If this procedure actually is advised to perform for any odd reason. Besides maybe replacing the TB new from factory.

primavera

I wouldn't be surprised to see dealers charging customers hundreds of dollars for the new throttle body while doing simple reset like that.