View Full Version : vacuum leak is driving me nuts!! need help plz

09-28-2008, 03:28 PM
Hey guys, need some help here as im at the end of my wits, i have a '92 325is, with a serious vacuum leak as far as i can tell, causing the idle to move anywere from 600rpm to about 1400rpm. whats i cant figure out is the leak is intermittent sometimes idles alright, with only slight variation (between 100 rpm) soemtimes terrible (changing by 500- 1000rpm) all the hoses appear to be okay and its as if i can here it sucking in major air somewhere underneath the intake manifold, or throttle body plate, i was thinking possibly idle control valve, but i dont have enough experience or the money to just start swapping out random parts, has anyone experienced a problem like this? your advice would be much appreciated!

thanks guys,

Sean Thompson

09-29-2008, 09:11 AM
Sean, the ICV is under the intake manifold and plugs into a plastic coupler that goes into the intake.. I would check this as maybe the "O" ring on the coupler is worn out causing your vacuum leak.. It's not that hard to get in there.. Just take off the tube from the alternator to the rad support cover so you can get your hand in there.. Another common area for e36's is the Intake tube from the MAF sensor to the Throttle body.. underneath where lines plug in.. You should be able to check these areas no problem... The intake one is tight.. but just take your time and you'll be fine!

09-29-2008, 07:54 PM
hey man thanks for the tips, unfortunately i already tried that, and although the hoses are old gettin soft and should be replaced, i dont believe its the source, also the clip on the coupling was broken, and had a little bit of play, replaced the o-ring which gave it a much tighter seal but still rough idle persists, one thing i found strange though i didnt mention before, the car will idle fine perfect for the first 4 or 5 minutes as it warms up, could a sensor kick in after its reached a certain temperture and cause the erratic idle?

09-29-2008, 11:04 PM
What year is the car??

09-29-2008, 11:28 PM
1992 325is

09-30-2008, 09:02 AM
Turn the ignition forward and depress the gas pedal all the way down 5 times.. the check engine light will flash in a sequence.. Giving you any codes that may be present.. try this and let me know what they say (hopefully you still have a check engine light) lol.

09-30-2008, 11:29 PM
i broke down and took it to bmw, they played with it for 2 hours i guess it wasnt acting up, but they smoke tested it, took the icv out, everything looked alright i guess, after 2 hours all they could find wrong was the o2 sensor before the cat failed, so i bought one going to throw it in tomorrow.. i doubt it will solve anything but it needs one so we'll find out p.s would a punched out cat mess with the backpressure and cause problems? im running out of ideas

10-15-2008, 09:44 PM
it could be the MAF
maybe you have a bad head gasket and letting some coolant in the combustion chamber, check your coolant level.
the O2 sensor might be the solution, there is a chance that it might solve your problem.
how does the car sound is it galloping?