Hoping someone out there can help me out. I did an e36 M42 swap. I swapped out the e36 intake manifold for an e30 manifold. I am still using the e36 throttle body.
Upon startup I had the breather in the valve cover capped and the vacuum port in the the intake capped. I ended up with fairly strong crankcase pressure at the oil filler cap and a leaky valve cover gasket car ran like crap idle all over the place, very rough. After some research, I realized that I need to vent the crankcase and add vacuum to it. I installed a catch can with a hose from the throttle body to the catch can and a hose to the breather in the valve cover. The car ran much better, but the idle went all the way up to about 1700 RPM and surged between 1500 to 1700 RPM. It now has a very strong vacuum at the oil filler cap. It seems to be a vacuum leak thru the catch can. If I slightly pinch the vacuum line going to the catch can I can get it idle just about right. Is there something that should be regulating how much vacuum is going to the valve cover (crankcase)? I know the e36 intake manifold has a little PCV / CCV valve built in, but I cant seem to find one listed for the e30 M42. I am stuck between having to much positive pressure or to much vacuum on the crankcase breather. It is surprising to me how it affects the way the engine runs to the degree that it does.
Am I missing something here? Will a smaller vacuum hose on the intake limit the vacuum (my instinct says no).
Any help appreciated, this seems to be the last bug I need to work out to get it out for a drive.
Thanks