LNF PCV Anti-coking drain back system
07-01-2014, 10:01 PM
#281
the instructions with the kit are comprehensive; it is essential that you either have clean valves or get them cleaned. This kit does not clean valves it prevents the continued deposition of oil on the intake valves. So far we have learned quite a bit about this coking issue. While DI valve coking is not unique to the LNF engine, its clear that bisecting the main vent line and inserting a drain back seperator does an effective job in the primary source of oil in the inlet tract.
The inlet manifold pcv valve can be defective, and I have found it so in quite a few de coke jobs on LNF I have done. If the IM pcv valve is reluctant to close until high boost levels hit it, or doesnt close at all, the build up becomes severe and the car really runs badly.
Sometimes I have encountered LNF with issues that the PCV upgrade evidentally could not deal with. Generally that has been cracked piston ring lands, damaged rings, or even broken charge pipes.
If the engine health is good, its reasonable to expect the upgrade will keep your engine running well.
The inlet manifold pcv valve can be defective, and I have found it so in quite a few de coke jobs on LNF I have done. If the IM pcv valve is reluctant to close until high boost levels hit it, or doesnt close at all, the build up becomes severe and the car really runs badly.
Sometimes I have encountered LNF with issues that the PCV upgrade evidentally could not deal with. Generally that has been cracked piston ring lands, damaged rings, or even broken charge pipes.
If the engine health is good, its reasonable to expect the upgrade will keep your engine running well.
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Zo6balt (10-04-2020)
07-04-2014, 09:26 PM
#287
What I am saying, is if the valves are coked and then cleaned might as well replace the PCVvalve in the inlet manifold. Thats because over half the ones I test when I clean the valves are stuck open at varying pressures. Thats not good. I regard it as a 5 dollar maintenance item.
07-04-2014, 10:11 PM
#288
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However, if you ever get your valves cleaned, which you should, make sure to change your PCV valve while you have the manifold off.
07-05-2014, 02:39 PM
#289
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Now I am confused, why does the intake manifold need to be removed on the LNF to get to the PCV? I thought it was pressed into the valve cover near the turbo?
Last edited by SINISTER; 07-05-2014 at 02:50 PM.
07-05-2014, 05:37 PM
#290
07-07-2014, 07:26 PM
#292
The PCV is a plastic one-way valve that sits within a passage in the intake manifold up against the head. It has no hoses leading to it. You need to remove the intake manifold to get to it.
They can go bad. One of mine did. John can tell you how often that may occur.
They can go bad. One of mine did. John can tell you how often that may occur.
07-08-2014, 10:47 AM
#298
sinister did not know what the manifold looks like. There appears to be a lot of confusion about the PCV system and lots of opinions about it, many of them are wrong.
FOR THE RECORD.
There are two check valves in an LNF One is the FRESH AIR INLET (FAI) it lets metered air in from the inlet tube post MAF to the rocker cover port in the middle of the back of the rocker cover. There is a 4 mm orifice in this FAI tube. There is an UPDATED tube and valve as the nipple in the stock inlet tube can break from excessive pressure.
The other is the PCV VALVE ( dirty side) located in the inlet manifold as sox fan has show, that vents blow by gasses into the inlet manfold OFF BOOST.
The rocker cover port at the passenger side (front ) of the engine is routed stock to the turbo inlet port. It vents blow by gasses to the inlet side. As oil builds up combined with the blow by gasses running through the mezanine along the rocker cover to this port, it actually can drain out directly to the turbo inlet.
It is this issue that the Powell PCV upgrade oil seperator deals with, and drains excess oil seperated back to the engine.
As the engine tilts under accelleration or in cornering this issue with oil draining into the turbo inlet gets worse, which is why Wangspeed found he can collect as much as 500 cc of oil in 20 laps on track with the car, but collects less than that over a month of street driving.
The upgrade works.
The understanding of how it works, appears to be (how can I say this politely?) VARIABLE on here. There is a delicate balance of vacuum and the PCV orifices and paths of least resistance for blow by gasses to vent. The PCV upgrade really does a good job. The latest change as of July 1 to the system makes it easier for folks to plumb without issues; the next big change will be a full time vacuum pump but thats not needed for anything other than the extreme track guys imho....any parts of the PCV system not in good order like the FAI or the IM PCV valve will give issues, as will any leaks especially at the MAP sensors for example. Hope this helps
FOR THE RECORD.
There are two check valves in an LNF One is the FRESH AIR INLET (FAI) it lets metered air in from the inlet tube post MAF to the rocker cover port in the middle of the back of the rocker cover. There is a 4 mm orifice in this FAI tube. There is an UPDATED tube and valve as the nipple in the stock inlet tube can break from excessive pressure.
The other is the PCV VALVE ( dirty side) located in the inlet manifold as sox fan has show, that vents blow by gasses into the inlet manfold OFF BOOST.
The rocker cover port at the passenger side (front ) of the engine is routed stock to the turbo inlet port. It vents blow by gasses to the inlet side. As oil builds up combined with the blow by gasses running through the mezanine along the rocker cover to this port, it actually can drain out directly to the turbo inlet.
It is this issue that the Powell PCV upgrade oil seperator deals with, and drains excess oil seperated back to the engine.
As the engine tilts under accelleration or in cornering this issue with oil draining into the turbo inlet gets worse, which is why Wangspeed found he can collect as much as 500 cc of oil in 20 laps on track with the car, but collects less than that over a month of street driving.
The upgrade works.
The understanding of how it works, appears to be (how can I say this politely?) VARIABLE on here. There is a delicate balance of vacuum and the PCV orifices and paths of least resistance for blow by gasses to vent. The PCV upgrade really does a good job. The latest change as of July 1 to the system makes it easier for folks to plumb without issues; the next big change will be a full time vacuum pump but thats not needed for anything other than the extreme track guys imho....any parts of the PCV system not in good order like the FAI or the IM PCV valve will give issues, as will any leaks especially at the MAP sensors for example. Hope this helps
07-09-2014, 05:04 PM
#299
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Yep, just bought the car...I have never seen it flipped over... I guess the F.I. air meter threw me off... LOL
So in a perfect world changing out the FAI and PCV and then installing your system is the way to go...right?
So in a perfect world changing out the FAI and PCV and then installing your system is the way to go...right?
Last edited by SINISTER; 07-09-2014 at 05:25 PM.