PCV system questions

[tmsperformance]

No, he didn't...:3d_frown:
He should - might actually learn something about how the 7M-GTE PCV system actually works.

I did read the thread, that is how I would assume to run it. I have never worked on a stock 7mgte. I can route mine totally different due to the FFIM, q45 TB and running a megasquirt due to not having that MAF. I have my top 2 valve cover hoses,the front valve cover hose and the block hose ran into a large baffled box filled with the scrubbing pads. At the outlet of the box, after the baffles I have a hose that is ran into a evac bung in the exhaust.

What exactly would be the best way to route them in stock conditions then?

 

[jdub]

I did read the thread, that is how I would assume to run it. I have never worked on a stock 7mgte. I can route mine totally different due to the FFIM, q45 TB and running a megasquirt due to not having that MAF. I have my top 2 valve cover hoses,the front valve cover hose and the block hose ran into a large baffled box filled with the scrubbing pads. At the outlet of the box, after the baffles I have a hose that is ran into a evac bung in the exhaust.

What exactly would be the best way to route them in stock conditions then?

1st rule: The crankcase is pressurized due to blowby.
2nd rule: Air pressure (or vacuum) will follow the path of least resistance...keep this in mind.

On the stock system, it's the TB (intake manifold) that provides vac...this covers over 90% of operating conditions. Under boost, flow reverses through the TB orifice (there is no check valve)...contrary to popular belief, the intake pipe does not provide vacuum. The reverse flow from the TB under boost over the cam cover outlets "pushes" the crankcase vapors to the intake pipe. This is obviously much less efficient and is the reason guys that try to use the intake pipe as the vac source for a catch can will always fail.

Take a look at IJ's pic (post #30), the catch can will not pressurize for two reasons:
1) The crankcase is marginally pressurized due to some blowby, creating resistance to that path.
2) The intake pipe is not pressurized, therefore no resistance, therefore flow goes to the intake pipe. This is exactly how the stock system works.

There is no significant vacuum at the intake pipe...to get any real vacuum, you would have to block the filter inlet to the pipe.

A PCV valve at the intake pipe that allows flow in the direction of the pipe, but not in the direction of the catch can will allow the TB to put max vac on the can...flow has nowhere else to go but from the cam cover outlets, to the can, to the TB port. Under boost flow reverses through the TB orifice...it will not pressurize the can because it has a much less restrictive path to the intake pipe...the pcv valve will not restrict this reverse flow. You also need this path to the intake pipe to allow crankcase pressure escape.

IJ's system used a FFIM - engine management does not have an impact on the PVC system. That applies to you as well. The crankcase needs to be under negative pressure to pull combustion byproduct out of the block. I'm not completely clear how you have yours routed, but the way IJ did is correct.

 

[tmsperformance]

1st rule: The crankcase is pressurized due to blowby.
2nd rule: Air pressure (or vacuum) will follow the path of least resistance...keep this in mind.

On the stock system, it's the TB (intake manifold) that provides vac...this covers over 90% of operating conditions. Under boost, flow reverses through the TB orifice (there is no check valve)...contrary to popular belief, the intake pipe does not provide vacuum. The reverse flow from the TB under boost over the cam cover outlets "pushes" the crankcase vapors to the intake pipe. This is obviously much less efficient and is the reason guys that try to use the intake pipe as the vac source for a catch can will always fail.

Take a look at IJ's pic (post #30), the catch can will not pressurize for two reasons:
1) The crankcase is marginally pressurized due to some blowby, creating resistance to that path.
2) The intake pipe is not pressurized, therefore no resistance, therefore flow goes to the intake pipe. This is exactly how the stock system works.

There is no significant vacuum at the intake pipe...to get any real vacuum, you would have to block the filter inlet to the pipe.

A PCV valve at the intake pipe that allows flow in the direction of the pipe, but not in the direction of the catch can will allow the TB to put max vac on the can...flow has nowhere else to go but from the cam cover outlets, to the can, to the TB port. Under boost flow reverses through the TB orifice...it will not pressurize the can because it has a much less restrictive path to the intake pipe...the pcv valve will not restrict this reverse flow. You also need this path to the intake pipe to allow crankcase pressure escape.

IJ's system used a FFIM - engine management does not have an impact on the PVC system. That applies to you as well. The crankcase needs to be under negative pressure to pull combustion byproduct out of the block. I'm not completely clear how you have yours routed, but the way IJ did is correct.

I'll try to get my ms paint skills up and draw something up to show you. I have 2 catch cans 2 inlets and 1 outlet on each. Each can has staggered 45* plates welded on the inside acting as baffles. In between them is the metal scrubbing pads. The inlets are on the top right of the can. The air/oil vapors travel through the top of the can, through the baffles and pads. The baffles only go halfway down the can. The separated oil sits in the bottom where the drain screw is. The now oil free air vapors travel back up the other side of the can through the outlet which is on the top left of the can into the bung that I have welded in the exhaust. The bung protrudes halfway into the exhaust pipe and has a 45* slash cut into to. When the exhaust pulses pass it, it creates a vacuum pulling the crankcase vapors out of the engine into the can. A vacuum source that will pull the blow by out my engine and not recirculate that carp back into my intake charge. I tried to go into as much detail as possible, hopefully that painted a picture in your mind of how its setup. I have 2 of those setups, 1 can does the 2 nipples on the valve covers and the other bigger can does the block and the front of the valve cover. The outlets of both cans are then tee'd into the one exhuast evac bung.

 

[NashMan]

ya exhaust dump is ok but some places will not let this pass for emission

that's the only down fall


with my system witch i left out was the venturi I added to my intake pipe, it was rather easy to make just ground down threads on a half inc pipe to male -10 an and slotted it

 

[tmsperformance]

ya exhaust dump is ok but some places will not let this pass for emission

that's the only down fall


with my system witch i left out was the venturi I added to my intake pipe, it was rather easy to make just ground down threads on a half inc pipe to male -10 an and slotted it

Good point on the emmisions. I don't have them where I live so I don't really worry about it. That is a nice little setup you got there.

 

[NashMan]

thank you sir

 

[MA67SupraTurbo]

GUYS, I have been smoking on idle, and running real rich. There is fuel smell in 3 day old fresh oil, and 3 day old plugs sooty as hell. I bought chrome 2Jzgte valve covers from Majestic motorsports, and don't have the PCV correctly hooked up because I'm retarded and didn't think it would cause trouble. Just got the car out and about a month ago, and noticed a fuel smell from inside the car (exhaust is half length/not done...long story) but was wondering if this could be the problem? Ran fine before, WTF!? HALP!

(tried uploading pic from droid, not working, neither is photobucket, workin on it)

 

[IBoughtASupra]

How rich? 10,11,12 at idle?

 

[MA67SupraTurbo]

The laptop reads 14:1, but it's fine until it warms up, the oil (now 20w-50..buying me time to test injectors)thins out due to fuel, then it starts to smoke. Just at idle, not driving. Dipstick smells like fuel, vapor from Valve cover hose(exhaust side) reeks of fuel, spark plugs are black where they see combustion. pcv system not setup, changed the oil like 3 times in a month. (only drove it like 7 days total, no meth, just lowest boost at only 16 psi!

 

[NashMan]

sounds like to much fule

if your wide band reads 0000's your have issue's 10 your in the rich zone


cause

to high of fuel persure
leaking fuel injector
to big of injectors (need to trim fuel persure)
bad tune


basicly your washing your motor right now that that really bad for ring ware and pin ware

 

[MA67SupraTurbo]

here is roughly how it will now be setup. Before the was no vacuum to valve covers, and I believe that was causing rich condition. AFPR not leaking fuel when ign was on..

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[MA67SupraTurbo]

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My question is does this look right? I want opinions before I change oil a 4th time, the old valve covers had only 2 ports, pcv valve intake side, and vent on exhaust side. With all these new ports on these valves, I don't know what is best. Had no over rich problem until new valve covers put in and not hooked up. Ran like a bat out of hell right after oil change and fresh plugs, BKR7E gapped .026, felt 30% stonger at low boost! Now the oil at turbo is thin and smokes at idle upon warming up, wicked fuel smell from oil cap. Don't wanna run it till I change oil...don't wanna blame injectors, they were fine, plugs all new and sootier than the old ones now!?

 

[jetjock]

I'm curious as to why you feel this would have anything to do with your rich condition.

 

[MA67SupraTurbo]

Because nothing changed but valve covers and a search brought up that possibility. So...injector failure?

Here's an example, but mine doesn't smoke this bad, he changed pcv and it stopped! As pressure was causing oil to go up return line in turbo.

For now, this is what I believe is the problem. My pcv works, just wasn't hooked up, when I do ANOTHER oil change, I'll post results, said he had to drive it hard for 3 days to clear out old oil...fml.

http://www.youtube.com/watch?v=kgJBoe5EUi4


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[FuzzayD]

<Opinion>um weird. im starting to wonder if i should ever listen to anything written on this forum after this thread on how to re-route a pcv system.
<Fact>The only reason toyota had the throttle bypass go through the same pipe that the rocker vents go through is that it's a tidy route to suction side.
<Possibility>You can route your rocker and engine block vents to a catch can that vents to atmosphere this will only increase HC emissions.
<Contingency variable*>Your iscv must source from after the afm and before the turbo, your tb bypass port must also come from here. *(on a stock system)
<Contingency> If when off throttle the engine tries to suck air backwards through the bypass port into the intake past an open valve down the piston rings through the crank case up the oil drain gaps and crank case breather through your catch can and in through its breather, you will draw in un metered air. So it is possible you might need a one way pcv valve inline with the isc.
The throttle bypass port needs to equalize pressure to atmosphere before and after the tb butterfly during closed throttle. a one way valve closing this line during boost could be used to remove that "boost leak".
<Fact> Most diesel two strokes have oil drain holes in their air boxes that constently vent boost to atmosphere but because of the size of these pipes there isnt enough space for any usable amount of boost pressure to be lost.

 

[NashMan]

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My question is does this look right? I want opinions before I change oil a 4th time, the old valve covers had only 2 ports, pcv valve intake side, and vent on exhaust side. With all these new ports on these valves, I don't know what is best. Had no over rich problem until new valve covers put in and not hooked up. Ran like a bat out of hell right after oil change and fresh plugs, BKR7E gapped .026, felt 30% stonger at low boost! Now the oil at turbo is thin and smokes at idle upon warming up, wicked fuel smell from oil cap. Don't wanna run it till I change oil...don't wanna blame injectors, they were fine, plugs all new and sootier than the old ones now!?

o am not to familure wiht the stock 2j pvc system

but i whould run that line form the catch can to the intake manifold with a check vavle and use the other vent as section vent for new clean air then once purssure raises it will just vent pre turbo and be burnt properly


pretty much the saem way as honda is done

 

[Poodles]

<Opinion>um weird. im starting to wonder if i should ever listen to anything written on this forum after this thread on how to re-route a pcv system.

Eh, everyone has opinions.

<Fact>The only reason toyota had the throttle bypass go through the same pipe that the rocker vents go through is that it's a tidy route to suction side.

That would be true if it was a throttle bypass (it's not).

<Possibility>You can route your rocker and engine block vents to a catch can that vents to atmosphere this will only increase HC emissions.

It's called Positive Crankcase Ventilation for a reason. It actually helps your rings seal.

<Contingency variable*>Your iscv must source from after the afm and before the turbo, your tb bypass port must also come from here. *(on a stock system)

It's not a TB bypass...

<Contingency> If when off throttle the engine tries to suck air backwards through the bypass port into the intake past an open valve down the piston rings through the crank case up the oil drain gaps and crank case breather through your catch can and in through its breather, you will draw in un metered air. So it is possible you might need a one way pcv valve inline with the isc.
The throttle bypass port needs to equalize pressure to atmosphere before and after the tb butterfly during closed throttle. a one way valve closing this line during boost could be used to remove that "boost leak".

Venting the catch can will just cause excessive blow by, it's not about un metered air.

<Fact> Most diesel two strokes have oil drain holes in their air boxes that constently vent boost to atmosphere but because of the size of these pipes there isnt enough space for any usable amount of boost pressure to be lost.

Not a 2 stoke diesel

 

[MA67SupraTurbo]

Okay I put in fresh oil due to the fuel smell, sealed the pcv system (connected hoses/clamped) and I now no longer have smoke. It would just smoke once the engine warmed up at idle! It seems the simple PCV setup should have been left as it was, right now I have the 2 valve covers sharing pressure vacuumed pre turbo, another line from the actual pcv valve also vaccumed on intake side (see pics). I am thinking I should cap the ports that link the valve covers (3 inch hoses above spark plugs between valve covers), what do you guys think? Also the recent oil dumped looked nice and fresh, really bothersome to drain perfect thick amber looking oil. Before that it had fuel in it and looked scary (kinda BHG style) and had a decent fuel smell, but all is fine and it is to my belief the PCV caused it all. I rebuilt the GT4088 hoping to bandaid it, but it blows smoke after boost, just like it's blown friend before did. Don't vent your pcv guys, now I need a new turbo, that was running kinda fine after rebuild. Could be oil in exhaust needs cleared out. (I'll probably rebuilt this one again, $50 aint as bad as $1K+)

Please don't tell anyone to vent their pcv system...

 

[onemancrew]

So is the conclusion to all this is leave the stock system in place?

 

[jdmfreak]

So is the conclusion to all this is leave the stock system in place?

But you can add a catch can "inline" with th stock system .... u will need to extend hoses

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