ok i just got my belt changed sence it shredded and swaped out my 3.33 for a 3.1 pulley, now i'am only seeing about 6 psi at 7000rpms and hearing this nasty sound when boosting. i have checked bov,entire exhaust system including manifold,and the charger piping with no success in finding the problem. what gives? my vac is at 18 at idle in drive and about 22 in park do any of you guys have any ideas as to what i should look at next? all you supercharged guys that know your stuff plz leave a comment or advice as to what you thik this could be so i can finally fix it . thanks dave :attention

 

Does the sound go "PSSSSSSSSHHHHHHHHHHTTTTTTTTTT"?

If so, then check your piping all the way from the SC to the throttle body.

 

Sounds like your belt is slipping.

 

Stephen is probably right now that I re-read this thread.

Your vacuum is normal, so don't worry about that.

 

Is that the nasty sound of squealing belt slippage you're hearing?
I see 7lbs boost with my 3.33" at 7000rpm btw.

 

Hey Ian,

Have you ever checked for boost leaks at where the compressor housing mates to the main body of the supercharger? I've got my SC on my workbench right now, and I was fooling around and took the housing (the snail shaped object) off and found it is an unsealed mating surface. If some of the allen bolts holding it on are not tight it looks like it could be a possible boost leak source.

Sorry to hijack your thread, Dave.

 

Yep. I've checked that.

My leak was fixed a couple of weeks ago. used the "Smoke-IT" thing at a local mechanic and they found the leak at my EGR. No other leaks anywhere. I had replaced the gasket before, but now realize it was the wrong one the whole time.

(The dealership had given me the wrong gasket which looked correct, but wasn't.)

I'm at 17Hg, which is the minimum of spec. low-end torque and high end hp feel pretty good on the butt dyno - but I'll be dynoing in a couple of weeks just to make sure.

(Sorry about the hijack also)

 

That's good news! I bet you're relieved the mystery is solved.

 

Well, the gauge still says I'm only getting 8PSI of boost - but I'm not trusting it anymore.

I am 100% confident there are no more leaks anywhere after using the "Smoke-IT" thing. pretty nifty device.

I'm probably just going to take the stupid gauge out and put my old Fuel Pressure gauge back in.

(For example, using a diagnostics vacuum gause, I now read 20Hg. On my friend's car (who is stock), with the same gauge, he reads 21Hg....)

IanS

 

belts are not slipping, and the sound is like a nasty bubbleing, exhaust leak kind of sound but as i said before i have no exhaust leaks what else could it be? before this started i would get 9psi at 7000rpms with the 3.33 pulley so i figure i sould get at least 11psi with the 3.1 pulley thats now on the car another thing that might help is that the sould seems to come from the passager side of the car under the hood-possible the supercharger it self but it was check also and appers not to be damaged in any way(pulley spins freely,and so do the blades

 

Ya know, I've often wondered about the way the egr tube is connected to the charge air pipe, which means the egr system is seeing boost pressure. Some sort of leaky egr system, maybe damaged by boost pressure, would give an exhaust leak kind of sound.

 

Didn't for me - and I was leaking a good 3 PSi out of it.

Besides, that sound would come from the driver's side more I would think.

Obviously, the only thing on the Pass side is the SC and charge pipe.....hmmmm.

 

And the rear bank header and y-pipe, but I don't know why an exhaust leak would cause a loss in boost pressure.

 

ok i checked my charger pipe and found that the maf has a piece missing from it(only able to get three nuts and bolts to hold it on the charger pipe that one piece is broken all the way to the little rubber ring that makes the seal on the charger pipe, i don't want to spend 500 dollars on a new one but would like to try and fix it i wonder if jb weld would hold up to the boost pressure?

 

Well, the EGR tube is at the back of the manifold, that's why.

not really an exhaust leak. (Air is flowing out of the manifold to open athmosphere, not air escapaing from the exhaust)

Or maybe you just mean the Y-Pipe and I need coffee.

 

You can get a used maf for much less than $500. Try carparts.com

 

did you hear any noises with this leak? i'am getting 10psi now but the car is very slugest and sill makes alot of noise when i boost, could the sc be leaking (at the snail)? i'am also not hitting my 7000rpm limit only about 6800rpms and one more question if my intake manifold gasket was bad would i see it on the boost gauge? the car has normal vac/boost for the pulley i have so i'am starting to lean on the fact that it isn't a boost leak but not sure where to begin looking for the problem else where

 

From installing MEVI's, if the manifold is not set right (main gasket is failing/not sealed) you see a HUGE loss in vacuum and the car shakes violently.