Hey I think i've got my rough Idle narrowed down to a vacumm leak. Ive changed my Map sensor and IAC, and when we put a vaccum guage into the intake manifold it only gives me a reading of 5" when ive been told it should be 14-18. I changed my plenum gasket about 15000kms ago and i dont have any oil consumption so i dont think its going out there. Any other suggestions besides getting it smoked to find a leak somwhere? Ive heard of sprayin either. anyone tried? If there are any ideas or websites please let me know. thanks.

 

yea brake clean

 

you can use brake cleaner when you hit a leak it will die or almost die you'll know ..BE CAREFULL NOT TO HIT ANY BARE ELECTRICAL trust me its not fun and the smell of singed hair last's a while

 

Ether will work, but opposite reaction. The engine will race when it hits the spot.
Again, watch the electrical, unless you need those pesky armhairs removed that keep covering your wristwatch

 

well I tried ether but if anything it made my truck almost die when i sprayed near my air box. thought that was wierd. Unless it is because it is allready really rich and the ether made it worse. Needless to say im stuck.

 

Another method is to take a piece of tubing and hold one end to your ear, move the other end along the vacuum lines. As you get closer to the leak, the hissing will get louder. The tubing isolates sound to a smaller area. You might want to do a test run and unhook a vacuum line, then move the tubing towards and away from the end of the line so you know what the sound will be like.

BTW, how do you perform a smoke test?

 

smoke test usually use a form of non hazerdous dust that is visible to the naked eye... usualy died white black or red... prettymuch you use a turkey baster type ./.. take a small amount of the dust and when you squeeze the end of the turkey baster type thing itll puff out the dust looking alot like smoke..you watch the smoke and see where it travels... if its pulled in to an area that would indicate a negative pressure leak and if it is blown away from a specific area that would mean a postive pressure leak... ive seen smoke test done with a liquid chemical and when it hits O2 it had a chemical reation and turned into a fine white mist/smoke ... theres many variations of the media used to do this test but all the principles are the same... hard to do with engine and automotive situations b/c of ambeint air being driving around by the fan or the belt... any moving air will disrupt the test

 

For a smoke test they pump your system full of smoke from a machine ( like a fogger at a dance or club) and you just watch and see where the smoke comes out of. and thats where your leak is. They are handy tools but a lot of shops dont have them. The good machines have a pressure valve on them and if the pressuse gets high it releases the smoke out of it. and if that happens then you dont have a leak.

 

Thanks for the info.

 

brakekleen is nolonger the preferred method for finding vacuum leaks. USE PROPANE just enriches the mixture wont make the engine bog or die it will just run it rich less chance of more problems. PLUS wont damage electrical if you are wofting it all over the engine compartment