My '93 940 Turbo had a great idle while it was cold but once warm it dropped enough where it was just above stalling(about 600-650). Once I gave it gas no problem but stop signs had me revving the engine just in case. I tighten up the clamps on all the vacuum hoses thinking there might be a leak. No change. Then I came across this youtube video about doing your own smoke test, which is really the only way to find very small leaks. And sure enough a small puff of smoke was escaping just below one end of the idle control valve. I tightened up a new clamp and the problem was solved. Great warm idle now. And I didn't have to pay $1000 dollars for a smoke machine. I did buy that cheap air pump from Harbor Freight but I'm sure it will have a lot of uses.

 

awesome, thanks!

 

I have a 93 240 that needs the smoke machine test. Where would you hook it up? Thanks

 

Disconnect any vacuum hose connected to the manifold and connect the 'smoke machine' to that inlet on the manifold.

 

Thanks Moe! Happy 4th! I remember the Shmoe!