CRC makes a spray MAF/sensor/electronic cleaner at auto parts stores that is safe to use. any cleaner safe for cleaning electronics(circuitboards and stuff)is safe though.

 

For those of you that are concerned with fuel trims, venting the valve cover to atmosphere will interfere with them. The PCV valve will pull in unmetered air through that port on the valve cover. Using a catch can with a filter on top will have the same effect. To keep air metering accurate, ensure it remains a closed system.

 

So there are no ill effects to capping this off? I've been using a breather for some time now.

 

You definitely don't want to cap off the valve cover, you don't want positive pressure in the crankcase. By keeping it a closed system, I mean that it ties in to the intake after the airflow sensor, so no unmetered air goes through that port.

 

yeah, if you cap it, you'll likely blow the dipstick out and have an oily mess since that would probrably be the path of least resistance to the pressure.

 

Probably a noob question... but is that only a concern for MAF setups? My engine was converted to a MAP setup.

I just noticed today that my valve cover tube (which I assume was connected to the old MAF intake setup) drips down onto the transmission and is making a small mess.

 

thread revival FAIL!

its dripping on ur tranny because u left it open.
get a catch can so it drains in the can instead of on ur tranny.
unmetered air relates to maf.

 

With MAF setups, any air the enters or exits the system between the MAF and the motor will result in actual AFR being different from target AFR. In closed loop, that means fuel trims. With a MAP setup, airflow is assumed from manifold pressure. The sensor is in the manifold, so any leaks before that are irrelevant, and any leaks at the manifold are accounted for by the sensor. Hopefully that makes some sense.