Vacuum leak at idle?

Black89XR7

Registered User
Ok, I drove my car to harbor freight tools today and everything was fine. When I came out of the store I started my car up and it ran at about 1200rpms and idled down(normal) and then started sputtering. Once the engine idled down my vac gauge went front about 19" slowly down and then the car died. Started it back up and it was still doing it but I kept it alive so I could get home. The car ran great just driving it and under boost(still pushed about 13psi). If i was cruising in 5th and let off the gas vacuum would go to about 21 and stay there. It was just when I would pull to a stop sign the car would idle down and start running like crap. I have the leak narrowed down the to drivers side and I can hear it hissing. I sprayed carb and choke cleaner on the bypass valve rod and the idle smoothed out. Im not sure if it is the bypass valve or if I also sprayed something else with carb and choke cleaner? How much "fun" is it to replace the bypass valve?

Thanks,
Travis
 
Ok, I drove my car to harbor freight tools today and everything was fine. When I came out of the store I started my car up and it ran at about 1200rpms and idled down(normal) and then started sputtering. Once the engine idled down my vac gauge went front about 19" slowly down and then the car died. Started it back up and it was still doing it but I kept it alive so I could get home. The car ran great just driving it and under boost(still pushed about 13psi). If i was cruising in 5th and let off the gas vacuum would go to about 21 and stay there. It was just when I would pull to a stop sign the car would idle down and start running like crap. I have the leak narrowed down the to drivers side and I can hear it hissing. I sprayed carb and choke cleaner on the bypass valve rod and the idle smoothed out. Im not sure if it is the bypass valve or if I also sprayed something else with carb and choke cleaner? How much "fun" is it to replace the bypass valve?

Thanks,
Travis


Holding the bypas valve in the open position at idel remove and plug the vacume line and see if your car runs ok. if it dosent, it may be a large line behind the upper intake or the intake gasket itself. You may be able to isolate the hissing noise by using a short peace of garden hose. Hold one end to your ear and prod around the engine compartment with the other it will "directionalize" the sound
 
Well i tried closing the bypass and it didnt help at all. So I spray some carb and choke cleaner on the inlet plenum and the motor died. So i guess I will be pulling the blower. It just figures though...the other night when i had it off I was like i wonder if I should reseal that....nahhh and put it together. Oh well I will put my teflon gasket on it and see what happens. I should also note that the motor has about 1600 miles on it since it was rebuilt so all gaskets are fresh.
 
It's all is determined by exactly what you mean by "fun".....:p

There is a small bolt right under the diaphragm (6 mm or smaller)....

You can feel it with your finger....

It could be a PITA if you drop that little bolt while you are re-installing.....:mad:

If you take your time, you should be able to "get er done".....:D
 
Well I pulled the blower off and right now i am waiting on the permatex to cure. I hope it dries fast because my mom will be pissed when she finds a eaton m90 laying in our kitchen:rolleyes:. I think the leak was from the inlet plenum so i resealed that and swapped the bypass valve. When I pulled the top ic tube off the nut was loose, so i am going to reseal that also. The good thing is that i have a ton of spare parts so when i need them i just swap them out.:D
 
Ok problem has been resolved. I think it was mainly the inlet plenum that was the problem but i went ahead and swapped the bypass and resealed the blower top to ic tube. Now it idles and runs fine.:D The strangest thing happened though...as soon as I fixed the blower all of my neighbors have been giving me dirty looks:D.
 
Well I pulled the blower off and right now i am waiting on the permatex to cure. I hope it dries fast because my mom will be pissed when she finds a eaton m90 laying in our kitchen:rolleyes:.

That's awesome. :)

When I lived at home, I always had car parts laying around my room...and also elsewhere. My favorite is the machined 302 engine block in the kitchen. :D I used the oven one time to rebuild an SC snout, but I don't think my mom was home for that. It was kinda smelly.

Glad you got it figured out!
 
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