MValentine

Alright so Im getting not so good mpg on my 00 ls400. I roughly getting around 14 in the city, and 18 on the hwy along with a low idle even so often. So ive been reading the write up on the MAF/TB Cleaning. It states to use CRC MAF Sensor Cleaner, and Valvoline Carb Choke & Throttle Body Cleaner. But I cant find the Valvoline Cleaner anywhere in my local area. Im guessing I can resort to using the CRC Throttle Body & Air Intake Cleaner right? Also does anyone know the part number for the Throttle Body Gasket? Im not sure if Im correct, but would the part number be 2227150042? Im also planning on doing an oil change, along with adding in Chevron Techron Concentrate Fuel System Cleaner aswell when I fill up.

PureDrifter

iTrader: (10)

1- remember NOT to touch the maf sensor, just spray and leave alone. follow directions on the can.

2-any modern throttle body/intake cleaner should work fine for the throttle body. An old toothbrush and razor blade will help get the carbon build-up off. BE CAREFUL and try to not get a large amount of cleaner on the electronic components of the TB.

3- correct part no. for an 8/'98-5/'00 built LS400 is 22271‑50041. For 7/'97-7/'98 LS400s correct part no. is 22271‑50040. (refers to BUILD DATE on the driver's door tag)

4-don't forget that the throttle body has a coolant line running through it so be prepared to wrestle with the hoses and medium amount of coolant that comes out, have distilled water and/or toyota SLL coolant to top off the system, and don't forget to re-bleed.

rfisherman

When I did this to mine I did not take the throttle body off. I was able to get my finger in the opening and used TB/carb cleaner sprayed on a cloth to wipe it off the throttle plate and throat area where the plate makes contact. Thicker deposits came off after scrubbing with a toothbrush then wiping.. I also took off the small plate on top the throttle body and cleaned that area as well. There are several small holes that may be clogged. I used a paper clip to clear them and then sprayed them c lean.

Doing all this did not take much time and straightened the low idle problem right up. If you get a persistent high idle after cleaning you may need to take off your negative battery post for a little while to reset ECU.

I know that doing this help idling and drivability but not so sure about fuel mileage. You may have another problem there. Both of mine get about 28mpg hwy and 23 give or take overall.

McPierson

iTrader: (3)

My TB was sticking so I did was fisherman did w/o cleaning any of the passages. I'm not sure how the TB would hurt mileage, but the MAF would hurt mileage. Good luck.

MValentine

Luckily I have two containers of Toyota Coolant, but hit me on the head with a tack hammer for being dumb. But how do I exactly bleed and re-bleed the coolant?

johnnyg66

Think PD means to fill coolant leave cap off run engine to get hot and let air bubbles come out. When I did mine I had to add more the next day.

PureDrifter

iTrader: (10)

this, but you don't fill it from the reservoir, you fill it from the fill point on the top of the throttle body since that's the highest point in the system.

you bleed it from the coolant cap.

LScowboyLS

my 96 is quite self-bleeding if you squeeze the hoses and burp while filling, the fluid drops in the reservoir after first hot-cool cycle, top it back up and you are done!

MValentine

Im going to drop by the Lexus dealer tomorrow to pick up a TB gasket along with an oil filter since Ill be doing an oil change aswell. I just have a couple more questions. Is the CRC MAF Sensor Cleaner safe to use on our MAF Sensors?? And also Im sure I know the answer to this one, but Ill ask anyways. the UCF10/20 TB is by wire correct?

PureDrifter

iTrader: (10)

UCF20 post change (aka '98-00) is a combination DBW/cable throttle body. The Drive by wire is the primary throttle control with a cable driven backup function that only opens the throttle a small amount by itself.

ls400geek

From the Factory Service Manual for 2000 LS on Filling, bleeding & re-filling coolant system (page number CO-3) :

(c) Slowly poor coolant into the radiator reservoir until it is "FULL".
(d) install the radiator cap
(e) Bleed the cooling system:
* Start the engine, and open the heater water valve.
* Maintain the engine speed at 2000-2500 RPM and warm up the engine.
(f) Stop the engine, and wait until the engine coolant cools down.
(g) Refill coolant into the reservoir until it is "FULL"

Regarding "open the heater water valve", this means turn on your heater to MAX in the car.

I let mine cool down for several hours or overnight, on a level surface, before refilling. I repeat the bleeding process one more time and let it cool down for several hours again and re-top it off. I keep repeating this coolant bleeding process until the coolant is at FULL in the reservoir, when it's cold.

This whole process might be different on older LS400's (I'm not sure). The 1998-2000 LS400's came with a thermostat with a jiggle valve in it to let air by.