What services you need and what you don't

Re: Edited List

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.

 

Re: Edited List

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.

 

Re: Edited List

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.

 

Re: What services you need and what you don't

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.

 

Re: What services you need and what you don't

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.

 

Re: What services you need and what you don't

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.

 

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

 

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.

 

Re: What services you need and what you don't

No one is going to have to do anything. The suggestion was to use the freebees available from the place you bought your new tires which, by 100K miles you would have done at least once, and make up your own mind. A free rotation/inspection every 4K miles is much better then an automatic $80 charge every 15K or 30K miles.

Not all businesses are as nasty as the one implied above. The Continentals I bought about 25K miles ago are still healthy. The shop balanced them correctly, the Toyota shop aligned the four wheels correctly, and there has been no undue wear between rotations. They look like they will get at least another 25K miles, not like the OEM Bridgestone baloney skins they replaced at 23K miles.

Of course we can't all live where the population is small enough that crook attitudes get rewarded with bad reputations and helpful outfits get the business lost by the crooks. Thoughtful folk learn to judge and appreciate the difference.

 

Re: What services you need and what you don't

Your suggestion of not spraying anything into the throttle body is the best approach. I would go at least one step further and suggest inspect the clamps, ducts, and filter first for any obvious loose spots and eliminate any leaks. Until you experience poor operation you should not disassemble the intake system. In older designs, having the crankcase ducted into the filter body was the prime cause of smutz on the throttle plate. Modern designs do not do that. Leaks in the filter, ducts, and joints ahead of the throttle body are now the prime cause of smutz on the throttle plate.

If it leaks, seal it. If it ain't broke don't try to fix it.

 

Re: What services you need and what you don't

Have you ever watched the fuel fog that hovers over the injection tubes in an idling race engine which incorporate radical valve overlap and direct port injection. The Atkinson cycle does not eliminate that fog. In fact it accentuates the effects of valve overlap.

And if the intake filter system leaks...?

See above. Dark accumulations are simple age effects. Until those "age effects" lower mileage and operation, cleaning them off is overly fussy and risks system leaks which will cause real problems.

 

Re: What services you need and what you don't

The 2000 GMC Sierra I used to have, I had to clean the IAC and TB twice a year. The MAF stayed very clean on that vehicle, as the hot wire sensor was located quite a distance from the TB, at the air cleaner housing

My 2004 Prius had fairly heavy TB and MAF deposits. The deposits on the MAF and TB blade would look like this after about a year of operation



My 2007 FJ Cruiser had heavy deposits after only a year. I don't have a good photo of the FJ Cruiser TB, but here is how the MAF looked



This is the MAF after I cleaned it with CRC SensorKleen. The bulb is the IAT



The two hot wires are buried inside the MAF body. One must use the supplied extension nozzle with the cleaner



The general consensus at the dealerships I asked is that the PCV is causing the deposits. These deposits are much heavier downstream of the TB blade, as the PCV is usually routed just below the TB blade for maximum engine vacuum



Oterhwise, I'd have to believe that I had defective factory air filters, and/or inlet hose leaks, on a 2000 GMC Sierra, a 2004 Prius, and a 2007 FJ Cruiser. Yes, I checked, no leaks, clamps tight, etc

 

Re: What services you need and what you don't

It's best to remove the MAF. This is extremely simple to do on the FJ Cruiser, and simple enough on the Prius



The Prius has electric throttle, but the return spring on the end of the shaft can be manually rotated with your fingers. Never, ever poke a screwdriver or other object down the bore

I use TB cleaner on the TB, and MAF cleaner on the MAF

CRC Industries Automotive Product Detail

CRC Industries Automotive Product Detail

On the FJ Cruiser, it also has an electric throttle, but no external return spring. I have to have the motor off, Ign on, and have a helper keep the gas pedal floored while I clean the TB

A note on cleaning the MAF and TB: more cleaner is NOT better. If you spray too much cleaner into the intake, you will have a hard time getting the motor started. A 1-2 second blast on the blade, where the blade seats, and the passages is plenty

The MAF needs maybe a 1 second blast on the hot wires to clean them. It's optional to clean the IAT bulb, it won't help the performance of it, but since you're already cleaning the hot wires ...

 

Re: What services you need and what you don't

Is this thread about the Prius in it's various versions?

I see no relevance to the actual experiences of folk who own a Prius with the adventures of folk who own FJ cruisers and GMC crap boxes.

The name Toyota on the medallion does NOT mean the vehicle is anything like a Prius; the FJ Cuiser definitely is NOT like a Prius.

Pretty pictures of actual Prius smutz is a better use for the bandwidth on this thread. If you can shoot an FJ, you can also shoot a Prius, if there is really anything to shoot.

 

The point I was *trying* to make, is that deposits CAN be found on TB blades, and on MAF sensors. It's not just a "Prius thing" although perhaps the Prius may experience more puddling in the intake manifold

Actually, my FJ Cruiser borrows technology from the Prius, such as electric assist power brakes. The MAF sensor on my FJ is exactly the same as on the Prius

I guess on my photo of my Prius TB, you didn't notice the deposits on the edge of the TB blade. When you force open the blade, the underside has fairly obvious deposits. Indeed, a few Gen 1 Prius TB's may stop working due to the deposits making the blade stick

Oh, another thing in common with my former Prius and my FJ, is that I routinely perform used oil analysis. If "schmutz" was getting through the air filter element, that would have been *very* obvious in the used oil analysis

 

Re: What services you need and what you don't

Most folk understand contaminants are a general problem. IF you had actually displayed a Prius throttle body I could understand your "mistake" in stating I hadn't taken notice.

I do understand the English language. I can read picture labels and recognize graphic commonalities.

I understand the effect of using words like "can be found" and "perhaps" in indirect and evasive writing.

Used oil analysis??? As my dah would say, what a crock of malarkey.

Just stick to your Sierra.

 

Re: What services you need and what you don't

I did display a photo of my Prius TB. Here we go again:



Or, a bit further away, with the airbox lid off



Take the airbox lid off your Prius, easy enough to do so. With a strong flashlight, shine it down the bore. You will notice deposits on the MAF, specifically on the IAT bulb (The hot wires are buried inside the MAF bore, you have to remove the MAF to inspect it)

I knew it was time to clean my Prius TB when I noticed deposits on the upper side of the blade. You will notice in the photo, discoloration around the edge of the TB blade. When you notice that, the TB blade has fairly heavy deposits underneath

So can the word "schmutz"

You stated that the air filter is allowing the deposits as noted. If the air filter was allowing "schmutz" through, eg a ripped air filter element, that would absolutely show up with a used oil analysis

If you or your pops refuse to believe in used oil analysis as a useful indicator of engine oil life, engine condition, etc, than perhaps you can let us know what is a better method. I'm all ears

I dumped that POS back in 2004. Any more comments??