Woosh / blow off valve noise at shifting ... but non-turbo.

[Mucci]

previous owner plugged it 

 

[zinz]

Does the woosh happen every time?

 

Does the engine “diesel” or run-on, after you turn it off?

[Mucci]

Yes every time. 
No dieseling. 

[Mucci]

Think I found it. Just went to remove the plugs and #4 was finger tight and looks like this above the threads

 

[Schnellvintage]

I remember (when the e30's were only a few years old) in the late 80's diagnosing  an M20 with the same issue.  The only difference was all the spark plugs were finger tight form the dealer (customer stated it was just serviced).  It sounded like a steam engine while it ran.  I was surprised it still ran....LOL

 

Glad you found it,

Matt

[TobyB]

Also, retighten your header nuts,  heh.

 

Whistling E30? The bolts that hold the cover plate on the intake manifold are just a tad loose.

 

 

t

 

[Mucci]

Ok well it wasn’t the spark plug, although the car idles a bit smoother now. 
 

I’m pretty sure it’s in the exhaust at this point; either a leak I haven’t found or something loose inside that makes the noise under back pressure. 

[xr4tic]

Sounds like a vacuum leak.

 

You could try disconnecting/plugging the brake booster vacuum line and see if it still happens, just be ready to stand on the brakes when you go to stop.

 

Otherwise, check and re-check every vacuum hose, you can try spraying starting fluid around the hoses/base of the carb and see if the idle changes.  Keep a fire extinguisher close by though.