Throttle body cleaning in cars.

[Coyote Chris]

There used to be a radio show called Car Talk, featuring Click and Clack, the Tappet brothers (Tom and Ray). They owned a car repair shop and would take calls from fans about car problems.
They said many things a dealer wants to do to your car is like vaccuming your wallet.
Like throttle body cleaning.
I have a 2018 Subaru Forester with 25,000 miles on it and an 8 year/80,000 mile factory "warrenty". I am getting ready for lots of miles this summer and had the CVT fluid changed and the differrential (s) fluid changed, per the manual. At the 30,000 mile oil change in 6 months, my dealer wants to clean the throttle body. The book does not call for that.
The car mostly gets used over the road between here and Montana and here and Oshkosh and about once a week to keep things "In use" and keep the gas fresh. I only use ethanol free gas. And I stabilize it.
(Oddly, a year after purchasing the car, I got a letter from Subaru American guaratteeing the CVT for 100,000 miles...I got on the forum and the tranny is not a weak point. )

Do I really need the throttle body cleaned?

 

[mikesim]

Over time, the throttle body acumulates carbon. When you turn the engine off that very last spritz of the fuel from the injectors doesn't get burned in the combustion chamber but vaporizes when it hits the hot engine components. This fuel vapor rises in the manifold and over time accumulates in the throttle body. I have never seen an accumulation of carbon so bad that it interferes with airflow through the throttle body, but I have seen accumulations of carbon that interfere with the function of the idle air control pintle valve. When this happens, the pintle cannot move back and forth freely resulting in an unstable idle or engine dying at idle. You can clean the throttle body as a preventive measure or wait 'til problems arise. It is really as easy job for a home mechanic. Get a old toothbrush or mechanics brush and a can of throttle body cleaner from the parts store. Remove all the ductwork/air cleaner leading to the throttle body. With the throttle body exposed, squirt the cleaner generously down the throtlle body and scrub the innards with the tooth brush. Pay particular attention to the area at the base of the throttle body where the idle air control pintle resides. After scrubbing, rinse the scrubbed area with the cleaner and you are done. Reassemble the ductwork and fire up the engine. It may smoke and run rough for a bit and then straighten out. Pat yourself on the back for saving some dough.

Mike

 

[suvcw04]

The remaining brother has a web site. Just type CARTALK into google. New content every 3 or 4 days.

 

[Coyote Chris]

The remaining brother has a web site. Just type CARTALK into google. New content every 3 or 4 days.

I would imagine Ray still owns the shop and runs the website. Good for finding small reputable shops. Tom passed some years ago. I bet I still have 100 shows recorded.....

 

[mikesim]

I would imagine Ray still owns the shop and runs the website. Good for finding small reputable shops. Tom passed some years ago. I bet I still have 100 shows recorded.....

Those guys were a hoot to listen to...

Mike

 

[DirtFlier]

Wasn't the show with Tom & Ray originally called "Click & Clack"?

 

[ST1100Y]

IIRC are throttle flaps Teflon coated... attempts of mechanical cleaning might cause damage...
Big deal are EGR valves though, those really suffer from soot and carbon build ups...

 

[mikesim]

Wasn't the show with Tom & Ray originally called "Click & Clack"?

The show on PBS was called Car Talk, with Click and Clack the tappet brothers. It was a Sunday staple for me as I spent the afternoon working on my own stuff in the garage. They also had a newspaper columm whose name escapes me.

Mike

 

[Coyote Chris]

The show on PBS was called Car Talk, with Click and Clack the tappet brothers. It was a Sunday staple for me as I spent the afternoon working on my own stuff in the garage. They also had a newspaper columm whose name escapes me.

Mike

I recorded many but somewhere on the web I downloaded a bunch of episodes for free (podcasts?) And saved them and backed them up. https://www.npr.org/podcasts/510208/car-talk

 

[Camelot]

I gotta say I’ve never touched the TB on my 208k mile ‘04 Honda Accord and it’s running just fine. At 25k miles I wouldn‘t even think about messing with it.

 

[mikesim]

I gotta say I’ve never touched the TB on my 208k mile ‘04 Honda Accord and it’s running just fine. At 25k miles I wouldn‘t even think about messing with it.

If your practice is to always use a Top Tier brand of fuel, that can go a long way in preventing carbon buildup in the throttle body.

Mike

 

[Frosty]

From 1998 Honda VFR800 Service Manual RE FI Throttle Body:

• Do nor apply commercially available carburetor cleaners to the inside of the throttle bore, which Is coated with
molybdenum.

Probably better tech in last 26 years, but something to think about and check.

 

[Coyote Chris]

If your practice is to always use a Top Tier brand of fuel, that can go a long way in preventing carbon buildup in the throttle body.

Mike

Many years ago, Car and Driver talked to the head of fuels for GM, At the time, the TT website had lots of specific data on how the govt lowered the standards for fuel and how many manufactures had crazy warrenty claims....gunked up valves at 5,000 miles for instance....alot of the language has been toned down on the TT website since 2005....but alot of gas makers have jumped on the TT bandwagon. If I can get it, I buy it. Long ago, when the manufactures were trying to get vehicles certified to meet EPA standards...they ONLY used Chevron with Techron. Only it wasnt available at the time at the EPA test site area....so the manufactures had it trucked in.

 

[Coyote Chris]

From 1998 Honda VFR800 Service Manual RE FI Throttle Body:

• Do nor apply commercially available carburetor cleaners to the inside of the throttle bore, which Is coated with
molybdenum.

Probably better tech in last 26 years, but something to think about and check.

I wonder if throttle body cleaner is different than Carb cleaner? At any rate, the service isnt mentioned in the official Subaru maintenance sheet. Might be worth an email to Subaru of America and a question for the Subbie forum. They (being the Honda forum) helped me a bunch with the VTEC solinoid/oil pressure switch solinoid assy. on my CRV

 

[mikesim]

It's not mentioned as a scheduled maintenance item because it really only needs to be done when needed. My Jeep has 180K on the clock and I have never cleaned the throttle body. I use Top Tier fuels and run a bottle of Techron thru the tank after ever oil change. For funsies from time to time I take a peek down the throttle body and it's clean as a whistle

Mike

 

[karl]

Most modern throttle bodies never see any fuel.

 

[mikesim]

Most modern throttle bodies never see any fuel.

It is the unburned fuel vapors that percolate up through the manifold that causes the deposits. This only occurs on throttle body injection and port fuel injection vehicles, direct injection vehicles are not affected by this.

Mike

 

[karl]

Pass