on my 97 model L67 swap it seems to be running a bit better since i grounded the Park/drive selector wires, and hooked up the VSS signal so it see's something coming from the VSS at the ECM, however now that ive been driving it more, and let a friend of mine who has alot of experience with the cobalt SS's he listened to my motor and said that the supercharger doesnt sound right at all, he let me listen to superchargers on youtube and how they whine, and mine sounds nothing like it, mine sounds just like a turbo spooling up almost, the funny thing is that if i unhook my belt to the supercharger it makes the same noise when the motor is reved up, granted the supercharger starts turning on its own which im assuming is from the vaccum on the engine, but its still odd that it makes the high pitch whine noise like a turbo even when the supercharger belt is removed.

anyone got any clues>? am i going to have to take video of the engine/sound for better diagnosis?

matthew

Anytime a motor starts making funny noises, I usually take off the accessory belt and run the engine just long enough to see if the noise is still present. But, with no water pump, you shouldn't do it for more then 20-30 seconds tops.

Stock pulley? What condition is the supercharger in?

These things may help people diagnose your issue.

If it sounds the same with or with out the SC belt then you are not generating any boost with the belt on. Check to make sure the boost bypass valve is functioning when the engine is at idle the valve should be pulling the lever upward and when revving the engine the lever should drop. Also check with the engine off to make sure the lever goes all the way down against the stop adjusting screw as they are known for the shaft sticking where it goes into the SC housing and not letting the bypass valve seal up. Dan

I agree. My BBV was corroded stuck open. Also turn the pulley by hand, see if you feel anything odd or hear anything odd.

Alternatively, take it for a drive with the blower belt off, you should notice a very signigant loss in power.

ok, checked the BBV, when i hit the throttle it pulls down, but only when the throttle is first hit, as the rpms climb it goes back to where it normally sits, i really think that this is something that im going to have to have a sound recording, unfortunately im having issues with my digital camera so best i can do is try to get some sound tomorrow. I can hear the supercharger rotors if i listen carefully, but the whine sound(turbo sound) is so much louder than the supercharger its hard to tell whats going on.

ill report back when i have a sound clip.

BTW this is a bone stock 1997 bonneville engine, stock pulley also.

matthew

That thing should whine like crazy. Sounds like you're not boosting. Have a Boost/Vac gauge yet? If not I'd suggest getting one. You could probably force the bypass closed for testing purposes and see if it works that way.

Sounds like a vac leak to me. Since you have a 97, did check all the ports on the SC vac tree and the the one under the snout? Check for any cracks/leaks.

If you are running an open element filter close to the IAC passage, then depending on the IAC position it can hiss/wistle pretty bad. I assume you can change the IAC parameters for the 3800 to calm this down (I could on the 7730/SBC).

Audio recording or no, the basic diagnostic steps remain the same for starters, make sure the BBV moves freely across 90* and check the diffrence with the belt off.

The BBV Im not sure of its behavior at no load, its computer controlled, so its possible that is normal. I thought it was %100 open in P\N\R.

You could try powering it manually, just unplug it and touch 12v to the pins, it should be open unplugged and rotate and hold *90 when powered.

ok, i got time to make video, i uploaded it to photobucket and i never can remember how to post the video's so here goes.

its about 60 seconds long, i took video of the engine, the whistle sound, and of the BBV, the BBV seems to shoot down when the throttle is FIRST pushed, but then moves right back up, i can hold the throttle at 4,000 RPM for 10 seconds, and the BBV only goes down when the throttle is first pushed, then moves right back up.

matthew

http://s88.photobucket.com/...current=DSCF5001.mp4

[This message has been edited by m0sh_man (edited 06-17-2010).]

quote Originally posted by m0sh_man: ok, i got time to make video, i uploaded it to photobucket and i never can remember how to post the video's so here goes. its about 60 seconds long, i took video of the engine, the whistle sound, and of the BBV, the BBV seems to shoot down when the throttle is FIRST pushed, but then moves right back up, i can hold the throttle at 4,000 RPM for 10 seconds, and the BBV only goes down when the throttle is first pushed, then moves right back up. matthew http://s88.photobucket.com/...current=DSCF5001.mp4

That bbv operation is normal.

quote Originally posted by darkhorizon: That bbv operation is normal.

Correct, with out PCM reprogramming, it will not boost under a neutral/park condition.

Edit: I think I figured out your problem. In the first post you said you grounded the park/neutral wires. If so and the PCM is always seeing that it is in park, then it will not boost. Just when the throttle is first pressed, like what you described. You need to have it reprogrammed to allow it to boost. What trans are you using?

[This message has been edited by Freshj (edited 06-17-2010).]

im using a getrag 282, i grounded the two wires that fieroflyer posted for me to ground.

still doesnt explain the whistle sound that the car is making, im sure you can hear it in the video, its alot louder than normal supercharger rotor noise.

matthew

Well if the BBV is constantly open it could make a whistling noise. I've never tried driving one like that, so it would be hard to say.

quote Originally posted by Freshj: Correct, with out PCM reprogramming, it will not boost under a neutral/park condition. Edit: I think I figured out your problem. In the first post you said you grounded the park/neutral wires. If so and the PCM is always seeing that it is in park, then it will not boost. Just when the throttle is first pressed, like what you described. You need to have it reprogrammed to allow it to boost. What trans are you using?

First off the range switch should be in drive (if no switch is detected, it defaults to drive as well). if it was stuck in park it would also have a 4000rpm rev limit.

Secondly, the pcm does not "not boost" in park/neutral.

Third, the best method of removing any bbv issues, is by removing the solenoid.

quote Originally posted by Fierobsessed: Take off the accessory belt and run the engine just long enough to see if the noise is still present.

I know I am quoting myself, but...
Do the SC Belt first then try. This will help you narrow it down.

The Boost bypass is opened by vacuum between the throttle body and the supercharger, and it is also opened when there is boost present AND the computer has opened the solenoid. So when you blip the throttle, the vacuum vanishes, closing the valve. But as the engine revs up, it starts to pull vacuum again as it is drawing in more air then the slightly open throttle body will allow in, causing the valve to open again. So without the load of the car on the engine, your BBV will remain open mostly.

with the belt off the car, the whistle/turbo sound still remains, that being said, my supercharger starts turning on its own even with the belt off the car.

matthew

The SC will turn with the belt off when the engine is revved up due to the air flowing through but it is not building any boost.
If the noise is there with the belt off then you are either dealing with a bad vacumm leak which should be making the engine run like crap or you could have a bad bearing.
Remove both belts and start her up to see if the noise goes away to eliminate the pulleys, water pump, alternator and A/C compressor as any of these can cause a lot of noise if the bearings are bad. Dan

Is there a noticable change in power when driving with the belt off? That will tell us if the SC is actually doing anything. If its not, put the belt on, unhook the linkage or otherwise pin the BBV shut and test again. You might want to do it in an open space if youve been driving without boost all along

If its more powerful, diagnose BBV. if its not, replace blower (in all likelyhood - though further troubleshooting is warranted)

the a/c compressor has been removed, a brand new bypass pulley was installed and that never changed the noise, ive tried three different alternators (all advance auto alternators) because the first had bad bearings, the second had bad bearings, and this one seems good, all thats left is the waterpump and the other pulleys, but if im not mistaken the noise does go away when all belts are removed, but ill double check, its not easy removing the belts though cause the tensioner for the supercharger is kinda behind my battery tray.

ill check over the weekend and report back.

matthew

Long weekend...

I resently changed a belt tensioner on a Honda V6 that sounded like something between a blower whine and turbo spooling up only louder. Removing the accessory belt helped narrow the problem down as I initially thought the timing belt was starting to walk off the cam cog wheels.

quote Originally posted by Fierobsessed: Anytime a motor starts making funny noises, I usually take off the accessory belt and run the engine just long enough to see if the noise is still present. But, with no water pump, you shouldn't do it for more then 20-30 seconds tops.

^ yes, try this. Will test is it is in the accessory drive system or engine.

Heck, I drove my Chrysler a few miles home with no coolant once (blew a freeze plug). Lots of engine-off coasting in neutral, but that was several years and many tens of thousands of miles ago. The engine still runs as good as ever with over 200K now.

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'88 Formula. 2800/automatic. Undergoing sunroof addition.

The rest of the garage:
'92 LeBaron sedan: 3.0V6/5sp
'77 Camaro: 350/4sp
'71 Fiat Spider: 1800/5sp
'71 Mercedes 220D: 2.2L/4sp
'70 DeVille: 472ci/TH400
'62 DeVille: 390ci/Hydramatic Jetaway