I think something may be wrong with my supercharger. When I get on the gas it sounds like the supercharger whine sometimes slips. It seems like it if whining at a very high rpm but the car is not moving like it use to. Could I have an air leak somewhere? Would a vacuum leak cause something like this? Can the bearing in the supercharger go bad? Sometimes when I shut my car down after the engine stops I can hear something spinning, and it doesn't sound smooth.

I think I am going to check my intake first, but do not know where to go from there.

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

Doesn't sound like a blower issue.. Do the rpms drop off when you hear it cut out? Reason I ask is because when my trans was low on fluid and i'd punch it, you could hear the whine get really jumpy.

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1998 GTP (L32 swap) | 2000 SE (L67 swapped)

Why buy something sensible with a RWD setup when you can build something really stupid, like this

No they the rpms don't drop.
Sometimes it sounds like the whine is hiccuping. It is very hard to describe.

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

Can you get any scans when this is happening? There could be something wrong with the boost bypass valve.

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12.3 @ 108 w/ 1.7 60'

I can scan. What perimeters are you looking for. I have an autotap with enhanced perimeters, and when I posted them once I gave a bunch of unneeded info.

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

RPM, MPH, Boost, MAF, LTFT, O2, Timing, KR, TPS, MAP, IAT, ECT, AFR

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12.3 @ 108 w/ 1.7 60'

Sorry guys I have not had time to scan yet. Been really busy with school and work. I noticed today that the supercharger whine makes a stuttering sound (all most like a rev limiter) when I am at WOT. Someone I talked to thought maybe it could be a vacuum leak. How do I check this. Do we have a boost bypass? Could it be working improperly?

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

Could be the MAF sensor.. your description sounds like it could be similar to what my car was doing before the MAF died and caused a code.

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if it is the maf you can unplug it and use the IFYOURSCREWEDINTHEASS tune and test the maf easily

Sometimes my car does that right after I start it up and drive. If I just let it run for a few before driving I never have the problem.

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05 GTP, TOG's , 3.5 pulley, ZZP 1.9 rockers, K&N CAI, OVERKILLED, poly mounts, GMPP suspension, F-body brakes

Now I do not know if it is the supercharger or the transmission. It feels like the car is almost running out of gas when the rpms are high and the car is about the shift. It almost sounds like a load clicking noise. I think I am going to have to take it to the dealership. I might first put in the original pcm and air intake to see what happens.

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

The supercharger snout coupling could be bad if it's making a loud clicking noise. If it's slipping that will change the boost level and the sound of the whine.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

If it is only happening a WOT and it sounds like it's hitting the rev limiter it could be the plug wires arcing under load, how old are your wires? Also check your coils.

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12.3 @ 108 w/ 1.7 60'

I don't know what it is. I think it may be the transmission.
When the rpms are close to 5500 it really starts to studder (like it wants to shift but wont). I do not think it is shifting like it use to.
Its like it has no power at high rpms.
It maybe time to trade her in before it goes out completely.

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

It does sound like your trans is going out now that you say that. That's why I got the G8, the trans was starting to slip on my CompG at 85,000 miles.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

arcing plug wires will do exactly what you are describing, how old are yours? I had the same thing happen to me after I washed my engine, it wouldn't do it while cruising, only at wot just before the shift. Check your coil packs for rusted terminals as well.

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12.3 @ 108 w/ 1.7 60'

Stock plug wires and plugs, at least I have never changed them. I have 60,000 miles now (purchased with 28000 miles).

What do I look for on the wires?

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

Start the motor and look at the wires in the dark, if they're arcing you will see sparks.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

The problem was the engine. It must have been a piston slapping or something. Took it to the dealer and they drove it, the tech drove it for about 5 minutes then it blew up. Had all kinds of parts come out from under it. Now when it starts it makes the awful noise all of the time. Around $5000 to get a new block/engine. Just traded it in on a 2007 Jeep Commander with a Hemi. I will miss everyone and still check the boards.

Thanks to everyone for all of the help over the years. Demod is in the classifieds.

Trevor

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2004 Grand Prix GTP Comp G
Modified K&N Aircharger, Inferno package, SPO Satin Nickel grille inserts, Wind deflector on sunroof,

^^^ we have a big mopar following on here

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Dam! I'd have a heart attack if that happened to me! Good luck with the new Jeep!

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Why have more money than brains? Cuz RACE CAR :

That was a rod knocking and the bottom end blew out. So did they give you a good price for the car since the tech destroyed the motor?

You should have bought a G8, it will eat up that hemi. Good luck with your new truck!

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

Dang, mine never does that, that really sucks. But if it did I'd probably be crying

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05 GTP, TOG's , 3.5 pulley, ZZP 1.9 rockers, K&N CAI, OVERKILLED, poly mounts, GMPP suspension, F-body brakes

Don's right-that sounds awfully shady.
You bring the car in to diagnose a noise and wind up with a $5,000 repair bill for a new engine after the tech blows it up?
Someone would be hearing from my lawyer.

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2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

That's insane. These engines are usually indestructible, What the hell did the tech do to it!?!
Lol, Good luck with the new purchase.

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2009 Pontiac G8 GT- Roto-Fab Intake, Roto-Fab Radiator cover, Superchips Cortex Tune, Tinted Tail lights, Corsa Cat-Back Exhaust, Tinted side markers, Painted GXP Diffuser, Tinted Reflectors, Painted Grilles.