What services you need and what you don't

[rusty houndog]

Originally Posted by bigbearballs

This is it? Wow!

After your helpful posts, this is what I'm down to. Does this sound right now?

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3) Change transaxle fluid

4) Engine and inverter fluid

6) Throttle plate cleaning

8) Alignment

9) Air and Cabin Filters

Forget the throttle plate cleaning.
This engine operates in such a way that the throttle plate is constantly being cleaned by the intake fuel mixture between intake pulses.
Just another one of those ripoffs by unscrupulous service writers.

For alignment, keep an eye on tire wear or have it checked when the wear pattern indicates a problem, or if you hit something on the road AND the car handles weirdly.

This site has had expensive discussions about intake air filters. Get a permanent filter and forget the filter for the intake. The cabin filter is another whole matter, but it's easy enough for you to take care of. Get the Fram heavy duty filter and knock it clean every so often.

This Prius maintenance thing ain't rocket science.

[Patrick Wong]

Originally Posted by rusty houndog

Forget the throttle plate cleaning.
This engine operates in such a way that the throttle plate is constantly being cleaned by the intake fuel mixture between intake pulses.
Just another one of those ripoffs by unscrupulous service writers.
...
This site has had expensive discussions about intake air filters. Get a permanent filter and forget the filter for the intake...

How many miles on your odometer? If you have more than 50K miles have you actually inspected the throttle plate?

If your car has logged a reasonable number of miles and you inspect the throttle plate, you will see an accumulation of dark gunk on the edges of the plate and the interior of the throttle body. This results from exhaust gases that come back up from the intake manifold and deposit on the throttle plate. Eventually this can cause engine no-start problems.

The reason that the exhaust gases accumulate is because the intake valves stay open beyond bottom-dead-center as the engine operates under Atkinson cycle. Classic is especially prone to this as the intake valve timing stays open longer compared to 2G.

Regarding engine air filters, I change my filter at 15K mile intervals using the Toyota-branded filter. However if you wish to mess around with periodically cleaning and oiling a "permanent" filter which may let more dust in vs. a paper filter, have at it.

[galaxee]

periodic alignments are important to keep your tires wearing evenly BEFORE they are damaged by uneven wear. good tires are expensive, preventive maintenance is cheaper than replacing tires early.

i see rusty is an extreme minimalist, which is fine. but preventive maintenance has its place, it is cheaper in the long run.

[jayman]

Originally Posted by rusty houndog

Forget the throttle plate cleaning.
This engine operates in such a way that the throttle plate is constantly being cleaned by the intake fuel mixture between intake pulses.

Not really.

The PCV system introduces oily vapors into the intake manifold. Any vehicle with a PCV system will have interesting deposits downstream of where the PCV hose is routed, which is below the throttle plate

A poor quality oil that easily breaks down will contribute to deposits. Operation in arctic temps - like we have here in January - will absolutely contribute to excess deposits in the intake manifold

I used to think the Prius deposits on the TB and the MAF were just the result of the Atkinson cycle. For giggles, I checked the MAF on my FJ last fall and it had the SAME deposits

I then reached the conclusion that 1) the VVT was causing this; and 2) normal PCV operation in winter arctic temps were also responsible

Yes, the TB in my FJ also had deposits. So I cleaned both the TB and the MAF in my FJ.

[rusty houndog]

Originally Posted by galaxee

periodic alignments are important to keep your tires wearing evenly BEFORE they are damaged by uneven wear. good tires are expensive, preventive maintenance is cheaper than replacing tires early.

i see rusty is an extreme minimalist, which is fine. but preventive maintenance has its place, it is cheaper in the long run.

Well, there are some obvious things I did not say; tire condition inspection every four thousand miles at normal rotations indicates any need for alignment. Otherwise, alignment is a waste of money. The tire shop I visit provides rotations free and it takes a very short time. Tire inspection directs the need for alignment and is much more frequent than "normal" service cycles.

Something to think about; tire shops are astute finding undue tire wear. They have a vested interest in finding any uneven wear because they can then sell more tires. Notifying customers of the need for alignment also endears them to their customers.

Well, maybe endear is not the right word.

[rusty houndog]

Normal throttle body deposits are cause by smutz that gets through the intake filter. In Prius Atkinson engines, that smutz gets washed off by the fuel air mix that is immediately next to the throttle body when the intake pulse reverses. Reversal effects at the throttle body are slight, but enough to keep the plate area clean. The double intake filter used normally on the Prius keeps all that smutz at a very low volume.

If the exhaust gases at the intake ports were making sticky deposits on the throttle body, why has the intake valve not seized up? After all, it will be exposed to the full effect of any "sticky" deposits. The reason is in the first paragraph; smutz getting through the filter causes throttle body deposits and there isn't any valve stick effect from the exhaust gases in the intake port.
We have the blessing of detergent fuel to thank for that second benefit.

[Patrick Wong]

Originally Posted by rusty houndog

Normal throttle body deposits are cause by smutz that gets through the intake filter. In Prius Atkinson engines, that smutz gets washed off by the fuel air mix that is immediately next to the throttle body when the intake pulse reverses. Reversal effects at the throttle body are slight, but enough to keep the plate area clean. The double intake filter used normally on the Prius keeps all that smutz at a very low volume.

If the exhaust gases at the intake ports were making sticky deposits on the throttle body, why has the intake valve not seized up? After all, it will be exposed to the full effect of any "sticky" deposits. The reason is in the first paragraph; smutz getting through the filter causes throttle body deposits and there isn't any valve stick effect from the exhaust gases in the intake port.
We have the blessing of detergent fuel to thank for that second benefit.

1. What is your basis to say that the throttle plate is clean? Have you owned a car with sufficient miles logged so that you have first-hand experience - or is your assertion based solely upon speculation? I have personally seen these deposits on many higher mileage Prius including two that I owned. If you still have trouble with this, then find an higher mileage Prius, remove the air filter housing cover, and look for yourself.
2. If you are using a high-quality paper air filter and change it when it gets dirty, then there is no "smutz" that gets through the filter.
3. What fuel/air mixture are you referring to? Prius uses individual fuel injectors that inject immediately upstream from the intake valves. I wouldn't count on residual HC that rises up from the intake manifold to the throttle plate to clean anything. Again, the evidence is that higher-mileage Prius have dark accumulations on the throttle plate and throttle body.

[richard schumacher]

Is there a MAF-safe spray-on cleaner? Or does safely cleaning the plate require disassembling the thing?

[Patrick Wong]

Hi Richard,

Throttle body cleaner should not be sprayed on the MAF since the cleaner leaves a residue. You can use the plastic wand supplied with the cleaner so that you direct the fluid only where you want it to go. I suggest using the least amount of fluid necessary to clean. If the MAF needs to be cleaned, you can buy a separate cleaner for that purpose.

In my case, I have had good results by removing the air cleaner housing, then using Q-tips moistened in rubbing alcohol to scrub off the throttle body deposits. I like this method because it doesn't introduce more fluid into the intake manifold. However it requires some time to remove the housing so if time is of the essence, it is much quicker & easier to use the can of spray cleaner.

[galaxee]

Originally Posted by rusty houndog

Something to think about; tire shops are astute finding undue tire wear. They have a vested interest in finding any uneven wear because they can then sell more tires. Notifying customers of the need for alignment also endears them to their customers.

yeah... and once the tires have shown uneven wear, guess who's just going to have to sell you a brand new set of tires + install + disposal for $500? the tire shop! whose best interest are we talking about here?