blowby??? what should i do

[240addiction]

Ok so yesterday when I am changing my oil I start the car to get pressure up so I could check the oil level when I turn it off, and I just so happened to open my oil cap and the car studered and almost died but recovered, and air is thundering out. what do I do I was going to go kat but I guess that will come later. Do you think that it is the valves or the rings I have a 1990 with a sohc and about 150k on the clock. thanks in advance guys

[98s14inaz]

That is normal, your car is supposed to do that when the oil cap is taken off. My 98 will start to stumble if I remove the oil cap when the car is running. It is probally because the intake is pulling unmetered air through the valve cover breather.

[Red coupe]

and air is thundering out.

I just started leanting about all this engin stuff but while crankcase pressure is normal shouldnt it be negitive pressure? air should be rushing in of his oil filler cap and not out, right? also wouldnt the addition of unmetered air cause a lean fuel mixture and raise engin rpm instead of making it stumble? sorry if im just confussing the situation Im just remembering that in my text book when talking about oil leaks and crankcase pressure they said if anthing the crank case should be sucking in and that if oil was being pushed out because of positive pressure ic could be a hint of a clogged pcv. can some one sed some more light on the issue of crankcase pressure and blowby?

[240addiction]

I checked my pcv and it is ok I also had a good firend at a tuner shop tell me not to worry "it is normal. lets boost it" direct quote so i guess never mind thanks guys

[Altiman94]

check your compression and do a leakdown test. That will tell you what is going on with the motor.

[Thee 240sx Owner]

If your car almost stalls... thats alot of blow by..... do what altiman said and go with a compression and leak down test.. this will definately give you an answer