I have an Injen CAI and noticed today that my Air Flow Sensor was disconnected (the small hose portion btwn the valve cover and the sensor itself it looks like).

What does this do and what are the implications of having it disconnected? ALSO, I noticed that the typically high oil consumption has been non-existant, in that since this hose has been disconnected, I haven't burned a drop. Is this even possible or just a complete fluke?

Thanks

 

FYI: The piece that was disconnected is the rubber hose that comes out the top of #2 in this pic:

 

It measure the amount of air... (hmm... this doesn't explain anything...) Let me put it this way. If that thing is dirty or damage, your car will not start. You should see a very thin wire in there. Air passes through the wire creating voltage. More air means higher voltage... if I remember correctly...

 

#2 is not a sensor. It's just a hollow air chamber which fresh air enters to the valve cover and down the crankcase to mix with crankcase vapor. Then out through the PCV valve and finally to the combustion chamber to reburn via the intake manifold. It's simply part of the PCV emission system.

 

jtso, always commin through with the info.
good man

 

So having the rubber hose on that part disconnected basically meant I was bringing in unfiltered air into the PCV system, instead of filtered air -- is this right?

Strange how having this disconnected is correlated w/ me burning MUCH less oil. Maybe it's an unrelated cause, and pure coincidence, but it does make me scratch my head.

Thanks all for the info!

 

That is correct. Also, when the PCV valve is not operational during WOT, the crankcase vapor routing path actually reverses and out to the intake tube via the same part #2 due to the aid of vacuum from the TB. I'm thinking the empty chamber in part #2 is also served as an oil separator to collect oil during this reversal of air flow. Engines that have only a tube from the valve cover to the intake tube usually have oil film on the TB throttle plate.

 

My mechanically-well-inclined friend thinks this is a probably scenario:

Faulty "#2", assuming it's some kind of check-valve (if it was just a simple chamber, why not just make it a long hose?). If the check valve was faulty, maybe its bringing in the wrong amount of air and thus causing the PCV system to suck too much of the crankcase gases (ie: oil) and thus burn a larger amount of oil than is normal.

Since the hose is disconnected and I think this might have slowed/stopped the oil consumption problem, maybe it is the #2 piece that is faulty.

I'm going to inspect it tonight, and have already cleaned out the PCV valve w/ solvent to remove any residue and/or sludge, but it didn't appear to have much/any in there anyhow.

Is the above scenario plausible?

 

I don't think it's a check valve because if it is, the build-up crankcase pressure would blow out oil seals when the PCV valve is closed. In fact, the official description of #2 is air flow chamber. It might be used as an air flow resonator like the misc empty chambers in the stock air box.

 

Just checked -- it's just a funky-shaped chamber w/ no valve or anything...

Hoses coming from that were clean, no oil no grime, nothing.

PCV hose was lightly coated w/ oil but nothing major, and it's to be expected.

On to find another possible reason for the oil consumption.

 

Why does the PCV valve close at WOT? Too much crankcase vacuum?

 

Inside the PCV valve there is a piston like device with a spring behind it. It opens up with the aid of manifold vacuum which overcomes the spring tension. During WOT when manifold vacuum is low, the spring tension keeps the valve close.

Here is an example: