Crank Case breather question

[dogfriend]

I looked thru the manual and the vacuum diagrams. The PCV routing appears to be the same for both the SOHC and OHV engines.

Basically, the system is supposed to draw filtered air from the air intake tube just downstream of the MAF. The air is drawn into the right (passenger) side valve cover, down through the crankcase, back up through the PCV valve in the left (driver) side valve cover and into the intake manifold.

So, when you install the crankcase breather, instead of drawing air from the intake tube (metered by the MAF) you are drawing air from the engine compartment through the breather, down through the crankcase, back up through the PCV valve in the left (driver) side valve cover and into the intake manifold.

I wonder if the fuel trim is able to compensate for the extra air introduced? It would be interesting to see if the fuel trim is different with the breather vs. the stock system.

 

[aldive]

On the SOHC motor, the PCV valve is not on the driver's side valve cover.

 

[97greenmonster]

I have had no bad effects from this mod. It actually idled better IMO. We did the same thing on my friends camry, and it did the same thing, better idle ETC,

 

[dogfriend]

On the SOHC motor, the PCV valve is not on the driver's side valve cover.

Well, then substitute its location into the flow that I described in the post above. The PCV has got to be somewhere in the flow before it reaches the intake manifold. The PCV is basically a spring loaded one-way check valve that allows flow toward the intake manifold only.

Anyway, if the PCV valve and tube leading to the intake manifold are intact, then it is pulling crankcase gases into the intake manifold whenever there is a vacuum present (when the engine is running and the throttle is not fully open).

 

[rwenzing]

It would be interesting to see if the fuel trim is different with the breather vs. the stock system.

It's definitely different. The fuel trim must go richer to compensate for the unmetered air entering the system through the breather when manifold vacuum is high.

Depending on production tolerances and the condition of the engine in general, the fuel trim may be able to cover for the leak and prevent a CEL at idle and part throttle, closed loop conditions. However, the fuel trim is also used to calculate the Open Loop Fuel Multiplier. So, using the breather, the engine will run unnecessarily richer at WOT than the same engine with the factory PCV system.

 

[aldive]

. So, using the breather, the engine will run unnecessarily richer at WOT than the same engine with the factory PCV system.

Mine doesn't as confirmed with an AF meter. This richer condition would manifest itself in gas mileage also, yet mine never changed.

 

[rwenzing]

Mine doesn't as confirmed with an AF meter. This richer condition would manifest itself in gas mileage also, yet mine never changed.

Closed loop idle and part throttle FE would not change because the fuel trim can compensate and maintain it at stoichiometric. Open loop WOT mixture will be richer based on the percentage of the fuel trim compensation - that's how the engine control strategy works.

 

[aldive]

Sorry, my WOT AF is just fine. I test with an AF meter ( I use the LM-1 http://www.innovatemotorsports.com/products/lm1.php )

 

[rwenzing]

Sorry, my WOT AF is just fine. I test with an AF meter ( I use the LM-1 http://www.innovatemotorsports.com/products/lm1.php )

I've never used that one but I'm sure it's a good meter. We had ETAS laboratory grade wideband lambda meters at work. Anyway, the statement about the OLFM was just a side comment to the question about whether an open breather would affect the fuel trim. It does, no question.

 

[MONMIX]

I have a crank case breather

it just looks cool...

 

[97greenmonster]

Ha

 

[patrick112390]

On the SOHC motor, the PCV valve is not on the driver's side valve cover.

would you be able to tell me where i would put it on a 5.0 with the gt40p heads?

 

[CobraSVT1184]

I put one on my truck ill take a picture of it tommorrow with my cell phone for you.

 

[patrick112390]

I put one on my truck ill take a picture of it tommorrow with my cell phone for you.

id appreciate that!

 

[Jakee]

I agree, running the breather filter does affect the fuel trims. It is so small that people don't experience any problems what so ever. I'm running a filter like Aldive and Monmix and I went thru this debate when considering the filter.

I was told that if you run a filter on the valve cover, then you'd need to run a filter on the PVC side as well. When I ran a filter on the PVC side, the smell was very noticeable. This coincides with the diagram posted above. The PVC side is the "Vent" and the tube running to the intake is an "inlet". I've never smelled anything by running the filter on the inlet so I knew it didn't actually vent.

I noticed the diagram posted above says, "Remote air cleaner or air outlet tube". The word outlet is confusing because according to the flow on the diagram, it's an inlet. My testing confirms this.

My Summary - Running a filter will have no ill affects on a properly running 4.0 SOHC engine. It does more good because it keeps the TB clean along with the intake. The fuel trims have to be affected but it's so small that the PCM can correct it.

Also, if this is an "inlet" then why does oil get into the intake? It shouldn't. My thinking is when there is a certain amount of airflow thru the intake, a suction is created that actually pulls just a tad of oil from the tube (if it's connected to the intake)

Anyone agree?

 

[Cheesebrat]

I may not know the exact science behind it all but, I do know one thing, that ever since I put a breather like Aldive and Monmix have on their ex's, that my throttle body stays nice and clean. (before I did this I had to clean it about every four oil changes.) With this and a clean MAF my ex runs smoothly with no hiccups and idles even better than stock.

 

[97sprt4x4]

I just bought a No name CAI and it came shipped with i suppose two breathers and one hole in the aluminum tubing that i'm going to assume is for the intake temp sensor. is this possible? i see a lot of people with tubes coming off of their's could this be subsituted for a breather?

 

[97sprt4x4]

anyone?