Could somebody give me advice on this:
My car has been working ok for a while. Suddenly it began trashing
with black smoke.
Begining to check the air intake system I found oil in the air filter
and all around!!
The mechanic cleaned almost anything (filter and sensors) with no use.
Changed the O2 sensor , no use.
Changed mi ECM with another one I have. It worked ok, but still
trashing ( a little).
I don't have any repair manual for this car. Everything I have it's
from the web.
I need to know where are the MAS and MAP sensors. I'm almost sure it's
one of them, but cannot tell.
Thanks in advance!
PD. I cannot feel secure with my family in this car anymore. Am I
right or just exagerating?
A high Volume of Oil in the Air intake system means one thing, High
Crankcase Pressure. There are a few things that can cause it.
1. A fault in the Positive Crankcase Ventilation system.
2. Excessive amounts of Compression Blow By.
3. Excessive Oil Levels.
It does not matter if your 93 Cavalier has the 2.2, 2.3/2.4 quad 4, or even
the 3.1 V6. The ECM, O2, Mass or Map sensors, for that matter no electronic
controls of any kind will cause this issue. Any Mechanic that believes
Crankcase pressure is regulated by any forms of electronic control needs not
to touch a car.
If you have a 2.2L 4 cylinder or a 3.1L V6:
1. Change the PCV valve.
2. Check the PCV hose and vacuum supply for blockages or cracks.
3. Check the vacuum with a Vacuum Gauge
A. If no Vacuum or little is found, replace or repair the throttle
B. If sufficient Vacuum is found check compression.
5. If compression is with in tolerances, on all cylinders, remove Valve
cover(s). Check that the Oil Return gallies are not blocked. Then start
motor, and check for pressure coming thru the return gallies for the oil
A. if none is found, recheck compression on all cylinders, and do a
leak down test. Do cold, then hot.
B. If pressure is coming thru oil return gallies, remove cylinder
head(s). Check for bad gaskets or cracked heads.
If you somehow happen to have a Quad 4 car (Rare before 95), disconnect the
oil separator tube, and see if problem stops.
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