Gummed up throttle plate...

[AVConsult]

To my astonishment, upon pulling the ducting off the TB this week, and fingering the throttle plate, I pressed it by fingers "closed" and discovered it was sticking closed, requiring a moderate finger push to release it. I got the TB cleaner out and thoroughly scrubbed the plate and bore. The same exercise afterwards demonstrated no sticking.

This may have been a contributing cause to my wife's complaint of "lunging" behavior when she'd slow to turn a corner and hit the accelerator again. It would make sense that high vacuum acting on the throttle plate during de-accel would wedge the plate into the gum/varnish and the plate motor might overshoot a tad when working to release the plate.

What I'm more shocked about is a modern vehicle, moreover a Toy, with 44k miles and a gummed up throttle bore....

[rrgr]

would think it is a fuel issue. You use cheap fuel, ethanol, either one can cause guming. Use a branded fuel with cleaner in it and probably not an issue.

[Hajoca]

TB gumm is also caused by the PCV Valve not allowed to work effectively.

[AVConsult]

rrgr, don't think any brand of fuel would hurt or help this; it's just air and PCV fumes that go past the throttle plate.

Good idea to check the PCV valve, though.

[deadrx7conv]

Fuels and oils are blended to help prevent intake, valve, and TB deposits.

Stick with toptier gas if you're not already using it.
Stick with full synthetic oil.
Use a bottle of quality FI cleaner regularly.

History of fuel brands? oil type and oil change intervals?

At 70k, my TB is fine and clean.

I removed my 'carbon filter' from the air filter box. Maybe that helped vent the vapors after each shut down??? My airfilter is also chucked at least once a year(too much sand/salt from winter usage). Hoping that the clean free flowing air filter also helps vent those 'vapors'.

Its time to install those PCV catch cans or Racor PCV filters ;-)

Maybe its time to start using low-SAPS oils.

[nme7]

Any issues when trying to restart the car? White smoke?

[AVConsult]

no other issues or side effects other that the sticking throttle plate.

I would like to know (specifically) how fuel choice in any way affects the deposits on the throttle plate for an otherwise normally functioning port injected vehicle?

I get that OIL choice might have some effect, and maybe a significant effect depending on volatility. Using synthetic seems a reasonable suggestion as well given its high flash temp (possible lower volatility).

I'm having trouble imagining that the carbon filter (there is another thread that beats that to death) would have a *significant" effect on throttle bore deposits.

Checking the PCV for good function sounds like a good place to start.

[deadrx7conv]

Fuel vapors from low quality fuel would leave more deposits. What is the PCV venting? Blowby? which is defined as?

Anything that allows vapors to move freely can possibly prevent them from condensing and coating that TB. So, why wouldn't removing restrictive carbon filter or restrictive air filter help?

I don't have a TB issue at 70k miles. Obviously, its either my fuel choice, oil choice, carbon filter removal mod, air filter replacement interval, FI cleaner usage, or a combination of ALL. I've never had to clean a TB on any of my vehicles, off which many have hit 250k+. I never had to replace a gummed up or failed PCV valve either. Yours TB was sticking at 44k. There is a cause.

My normally functioning engines don't have a problem. Your engine must not be functioning normally if you have a TB issue.