Oil deposits on reverse side of throttle valve: Toyota vs other makes?

On a recent Best of podcast, the caller says she took her Corolla into the shop for a $40 oil & filter change. The shop suggested an extra-fee ($60) throttle valve cleaning, claiming it was probably gunked up on the other side. The caller agreed to the extra service, but told Ray that a dirty throttle valve was never a problem on her prior Honda. Ray said Toyota’s do tend to have this problem more than Hondas. Wondering why?

No indication there actually was a problem, ‘probably gunked up’ is a claim, not a fact. If they didn’t have an issue with the car, sounds like a waste of money.

Ray also implied it probably wasn’t necessary, but seemed to be aware that this was more of a problem w/Toyotas. Just wondering why? EGR system and/or PCV systems output too close to the throttle valve? I did find it coated w/oil & gunk & cleaned the reverse side of the throttle valve on my own Corolla when I had to remove the throttle body for another reason.

Throttle bodies get gunked up regardless of vehicle. Some models might be more known for it than others, I guess. I’ve always occasionally just cleaned them. If it causes issues, it’s more of a high mileage thing most of the time, I think. The “trailvoys” (I have an '02 Envoy, 4.2L) are known for it causing idling issues, but mostly at higher miles.

It depends on mileage and the shop, but if this shop was just suggesting it on the basis of nothing it was probably your run-of-the-mill upsell.

The best way I ever heard it described was using a fuel system cleaner in your gas tnak is like brushing your teeth, doing a fuel system cleaning where the throttle blade is cleaned, a cleaner goes in the tank as well as an induction service where it looks like an IV drip to decarbonize the induction side of the engine is like going to your dentist for your cleaning, you may not have a cavity but it is to keep you from getting one…
MAP - (Motorist Assurance Plan) standards, recommends this service being done every 15-20K miles or once a year, it is more of a preventative maintenance then a repair, although it can be added when needed for a given repair…

My buddy would do a quick scan of live data to see if the TPS was a little high at normal idle, if idle is normal but the TPS was a little high that meant the throttle blade is not closing all the way under normal circumstances…

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Keep it simple

If you are NOT experiencing idle problems, fault codes related to the throttle body, tps, etc., then don’t worry about it

My sister-in-law’s car recently had problems where it had a rough idle and would stall at a stop light

I cleaned the throttle body and all those problems went away

No fault codes whatsoever, btw

If there hadn’t been symptoms, I wouldn’t have touched the throttle body

Sometimes, less is more

I’ve seen way too many instances where a well-meaning person cleans the throttle body on a car that’s running perfectly, is NOT capable of doing a proper relearn and now they’ve got a vehicle with a messed-up idle, whereas everything was just fine before


Stalling at idle could be dangerous, with no CEL light on, meaning no warning to the average driver, is all the more reason to properly maintain a clean throttle body… If you maintain it then it will never get to the point of stalling due to needing to be cleaned…

A lot of people don’t even realize they have an idle problem anymore then they realize their shocks/struts are slowly wearing out… Heck, a lot of people don’t even realize they have a low tire even with a light on the dash… lol

And I 100% agree that a properly trained pro should do the cleaning, I have seen damaged TB after service from people that did it wrong as well…

I wonder how someone damages the TB just by cleaning it? About the only way I can think of is they damage the MAF sensor. But that isn’t damaging the entire TB, and that part is easily replaced. It would be possible to do some difficult to repair damage by prying on the throttle plate with a screwdriver or something, but that would be a demonstration of lack of common sense.

You don’t understand because you are not used to a drive by wire vehicle, they have motors with gears that can be damaged by opening the throttle blade improperly…

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Ford had this sticker on their throttle bodies before they started making throttle body cleaners.

Using anything other than throttle body cleaner would remove the Teflon coating



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I agree 100%… And I give you…

That would tend to fall under properly trained pro doing the job…

I worked with an IDIOT (and I’m being nice) A tech (anybody can pass a test) that blew his own engine while doing a FST… He was no longer allowed to preform FST’s on customer cars, nor his own since we got stuck loosing a parking space over it for a while…

FST??? What is that?

Fuel System Treatment

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How’d he do that? Flood it out and hydrolock it?

Pretty much… :rofl:

You supposed to run the engine at about 1800-2000 RPM’s and he did it at idle, or the throttle depressor came loose and it went back to idle… He was OK at somethings, but should have never been anything more than a C tech at best… He also didn’t use deodorant and by the smell, not very many baths either, so nobody wanted to be close enough to him to make sure he was doing it correctly… And in todays world, HR is afraid to fire someone cause of discrimination claims… It was not a religious thing, he just stunk, his nickname was stinky… but we were finally able to promote him to customer statice over F ups before he was able to tow his car off…

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Statice, what is that. Hopefully you didn’t mean customer service as what customer would want to be serviced by “stinky”.

Haha, yeah I have said MANY times on here in the open that I can’t spell for crap… :crazy_face:

I guess statice should have been status… lol

Promoted to customer status/statice (or whatever) means he was fired, not moved to another department…

It would help if so many things about the English language weren’t so bizarre. Like why does spell even need two ells? It doesn’t need two. And if lots of words that end in the same sound, like “-iss” - then why aren’t they just spelled that way? Or at least all the same as each other. Let’s pick one. “-us” or “-ice” - IDK. There’s so much weirdnus. Eye think ewe awl no what aye mean.

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“status” is probably from Latin.

Oh, I’m quite certain that most of the weird"nice" can “bee” explained “bye” philological analysis. (Or should that be “filolojical analisis”?). It doesn’t make it all any less weird.

And yes, the word status is from the Latin. And it meant stature/height. As “stature” that sort of works for the stratification meaning of “status” (high vs. low “status” people). But it doesn’t work for “status” as in category - employee or customer, for instance (as it first arose here).

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