So, I'm sorry if this isnt the right section for this and plz feel free to put it in the appropriate section. I had my check engine light checked after noticing it flashing and the car stuttering under load and it turns out I have misfires. The strange part of it all is its also pulling up code p0243. My check engine light has always been on, and it was due to o2 sensor and catalytic converter. So the misfire and p0243 code is New. Any ideas on what would cause the code to come up? If it helps, I recently gutted my air box, but I'm unaware if this code has popped up since I gutted it because I only checked the light again because of the stuttering. Any help would be great thanks!

Something is wrong with the boost control system. What kind of boost pressure do you have cruising and at WOT?

There are two components, the solenoid and the actuator. The actuator is active all the time. It's round, black, has a couple vacuum lines running to it, and a rod sticking out the bottom. The solenoid is a small black box near the actuator with a vacuum line running to the bottom of the actuator, and a wire harness running into it. It's only active when the PCM doesn't want boost, or less of it, and manipulates the vacuum to the bottom of the actuator.

In my experience, stuttering has been caused by the solenoid.

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WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

I would check the vacuum lines to those two components. I had the same problem and just stopped up the vacuum lines going to those two items. Everything is fine now. A buddy of mine told me basically what they do is not allow boost in reverse. That sounded stupid to me, but I traced the vacuum lines to those items and blocked them off at the source and boost works fine and the code went away. No adverse effects that I can see to this.

The boost would work fine, until the PCM wants to dump boost, like if there's knock happening. If it can't dump boost, knock quickly gets worse and then stuff breaks.

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WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

Ok, so i went and got my misfiring taken care of (bad coil). At cruising speeds I'm at just under 0 boost. When I give it power I'm getting about 4 use to get 5 after gutting the air box.

Oh and the stuttering is no longer happening

Good to hear the stuttering was fixed. Did the P0243 go away too? Your boost seems low to me. I thought Series II's ran around 7 psi.

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WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

Yes the P0243 is gone but I'm not sure if it's just because they cleared the check engine light or not? Since I've had it, it's always had 4lbs of boost and since gutting the air box I got 5. I'm not sure if what is supposed to be? Perhaps someone with the same engine cloud elaborate?