Snake Oil? Proprietary Throttle Body Cleaners and Tranny Flushes? (like BG)

Not on the 3.4.

 

Then where is that vacuum line in @CodeSeven second pic connect to? Even if its not directly to the IAC, the mass of the pollutants being recirculated are obviously building up into the IAC and throttle plenum via ported vacuum.

Even if it all starts as oil fumes, its being drawn in and subject to the heat in the combustion chamber. From that point it all ends up as the carbon we have to scrape and chip off.

 

Like I said, it goes to the "air assist" sub manifold and actually that system only carries clean air under vacuum from upstream of the throttle plate. It's the lighter colored one of the 2 smaller ports in the IAC in his pic. Go back and read post #42.

I would really like to see what you are calling the "second" PCV on the 2.7.

"Air assist" hose and plumbing.

 

See now that is interesting. Its not connected to the FPR is it. Curious as why that would be there other than to supplement the air mass available in addition to what is coming from the IAC at idle.

Possible does it provide vacuum to the fuel injectors? Older Bosch units used vacuum assist to increase atomization.

Ill be looking for a routing diagram for that, all ive seen are ones for the EVAP and EGR in the FSM.

First off, this is not my truck. My shit would never be this dirty.

 

This is mine.

Before a major seafoam cleaning. I used the seafoam spray as much as i could inside the plenum, couldnt really get much off. The throttle body i soaked in seafoam overnight, and i still had to scrub the shit out of it.

Manifold inlet for PCV right above the channellocks.





Inside the bore, on the right wall. Thats the intake for the ported PCV.

 

I see only the typical PVC system with one valve.

The function of the 3.4 air assist system is fully described in the last paragraph of post #42.

The 1st gen Taco FPR's are not vacuum modulated. The whole section in the FSM dealing with "testing" the FPR action by disconnecting what they call the "vacuum sensing hose" is completely wrong. I believe it's an artifact from an older manual mistakenly compiled into the newer volumes. That hose is a vent to carry any fuel from a leaky FPR diaphragm into the intake stream. It connects before the throttle plate where there is no vacuum present.
Only a few 3.4's had modulated FPR's, T-100's and maybe some of the first year Tacos. There was a VSV controled by the ECU allowing vacuum modulation of the FPR.
Here is a diagram.


This one shows the "air assist" plumbing, labeled "air pipe".

 

What are you talking about? Two lines, each with a valve screwed into the valve cover, one ported, one manifold. If its not a PCV, then what do you call it.

Also i think youre misunderstanding the function of the vacuum modulation on the FPR. If there is no input, vaccuum or electronic, how is is restricting the fuel return to maintain pressure? Even at that position, there will be some vacuum during acceleration, its at idle when there will be none.

 

Also thank you for the diagram. It appears to be like what i mentioned, a vacuum assist for the fuel injection system, to create a pressure differential at the point of fuel release. Also called air shrouding.

If you see a diagram for the BMW M42 engine intake system. It has similar setup to reduce pressure at the injector tip (it does it from within the injector) to allow greater atomization of the fuel. Similar principal of venturi injection.

 

In your post #48, the upper hose shows the PCV valve in the valve cover with a hose running from it to the intake plenum. The bottom hose is just a hose running from the TB to a nipple on the valve cover.
The "flow" goes like this, fresh air is drawn thru the engine by manifold vacuum. The PCV valve simply meters this flow.
It starts at the port on the TB upstream of the throttle plate (no vacuum) and is drawn into the valve cover and out the other end of the valve cover at the PCV valve then into the manifold to be burned.

 

The both lines have valves they connect to on the valve cover. They operate as check valves, though yes the opening does created a metered flow, as well increase vacuum at the point of entry. The FSM has you test the one-way check function as the first step of diagnosing the system. The lower one is just based on ported vacuum.

The lower one will have vacuum, a small amount of vacuum, but vacuum. It may just be enough to pull additional gasses into the intake as RPM increases. Why Toyota did this? Probably to satisfy the bureaucrats in California's CARB. Ive seen that the Federal emission version, the one without the wideband O2 sensor, has a different hose and valve on the upper line. In my opinion its unnecessary, just to ensure every bit of blowby is captured.

 

It is you that doesn't understand, it's a simple pressure regulator consisting of a diaphragm, a spring and valve. One side of the diaphragm is fuel the other is atmospheric pressure. Anything above a set fuel pressure will press against the diaphragm, the diaphragm pulls on/opens a needle valve bleeding off pressure. Google it.
If there was any significant/usable vacuum in the intake tube at higher speeds it would be cutting pressure, not a real handy function.

 

I dont think i need to google how a FPR works, they havent changed much since either of us were born.

Yes obviously all FPRs have a loading spring. This includes the ones you are thinking of on a welding tank or propane grill. The purpose of the vacuum line it to restrict flow and put additional load on the the diaphragm to compound the tension provided on the spring to hold the diaphragm closed (or close to closed), restricting fuel. Without this, you would be facing fuel starvation at WOT from the increased demand from the injectors. Its pre throttle because you only want it to do this when you step on the gas. It is calibrated to stay open without vacuum just enough to maintain a predetermined set psi.

I know you that know how vacuum advance on a distributor works. These are often attached to port vacuum to only advance ignition on acceleration for the purpose of raising combustion temperatures. If there was never any vacuum pre throttle, then ported vacuum advance would not function either.

 

The lower will not have vacuum. By all means post up the FSM section describing this test or any other documentation to support your claim. It's like you do not know what the "ventilation" part of PCV means.

 

Please google 'ported vacuum' and report back your findings.

 

now this is informative. had I known about this before, I would have noted it in my mention of the 3 way workings of the IAC valve. thanks for this!

but it still raises the question as to why is there only gunk buildup on the air pipes side of the IAC valve? the inside of my intake manifold was clean, and my throttle body was nearly spotless.

 

Seems that the PCV connected to the plenum bypasses the throttle completely. When at idle, all the vacuum draw is going through the IAC, with all the crap its pulling from the valve cover. Also is it possible that you had gone longer without cleaning the IAC, after already cleaning the throttle plate in the past?

 

I suggest you put a vacuum pump on a Taco FPR and watch fuel pressure as you add vacuum, it goes down.
The PVC fresh air source on the side of your TB is not "ported" vacuum as found in early "smog" carbs working with A.I.R systems. The Taco TB is simply an air valve not a venturi.
Or you could just put your vacuum gauge on what you are calling ported vacuum and tell us what you see. Been there done that.
Then there is the 3.4 with the vent line of the FPR connected to the resonator box a mile upstream from the TB. Again, been there.

 

but how can this work? doesn't vacuum increase with RPMs? wouldn't the FPR eventually cut off all fuel if you're high revving? Or is it doing just that and "governing" max engine RPMs?

 

He believes that the engine produces less vacuum and demands less fuel as RPM increases.

 

For this goat rope, vacuum is a function of mostly throttle plate position. Closed throttle, idle = high vacuum. Higher rpm, slight throttle opening like on the highway = high vacuum. Open throttle = less vacuum.

The Taco FPR is used in other applications where high vacuum at idle is applied to reduce fuel pressure. It's just not so on the Taco. In fact an early 3.4 SC mod was to stick/clamp a pin in the FPR depressing the diaphragm (opposite of vacuum) to get higher fuel pressure.
Here is a word for word quote from Gadget of URD, many years ago.
"The stock connection is to the main air induction tube which is really nothing more then a vent and gives a constant 43 PSI all the time."


Now back to the air pipe/sludge question. In your 3rd pic, the chamber in the IAC connected to the air assist hose is the cleaner of the 2 smaller chambers. It's on the opposite side of the IAC from where the hose connects, makes it a little confusing. The sludgy chamber is the passage that goes under the throttle plate to another chamber directly under where the PCV hose connects. Turbulence and the pulsing nature of the intake air force the sludgyness back into the valve and against/around the throttle plate. Plus it is possible that only the TB/intake was cleaned.