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Discussion Starter #1
Hey folks, new to the forum.

I have an '07 solstice GXP 5 spd stock with 59,600 miles that seems to only boost to 7psi even in sport mode. For a while it would drop a bunch of power and I had maybe 2 psi tops. Turns out the intake how had a plastic nipple that busted. I replaced the entire intake hose with an RPM motorsports cold air intake. The boost still cuts out. I then replaced the MAF sensor. Same problem. I've read elsewhere that sometimes the adjustment bolt for the down pipe will come lose and the valve will become stuck open or in the wrong position. When I took that route I noticed the previous owner locktighted the bolts to its not lose. Engine code only comes up with PO299 underboost.
 

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Note any odd sounds? Like a George Jetson car kind of sound when you floor it?
 

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Discussion Starter #3
No George Jetson sounds. I did notice that when I put the cold air intake on the turbo wine seemed louder. I've also noticed a metallic sound when I put the clutch in and the RPMs drop. My guess is the downpipe plate is making that sound when it opens and closes, but I'm no expert.
 

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Louder with the CAI is normal.

With no odd sounds, my first thought is that you're not surging the turbo, or experiencing a loose hose, but I would check those hose clamps again just to be sure. My SOP is that I tighten a hose clamp, and then tighten it the next day, too.
 

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I will do that. I'm just very struck by the issue. I'd heard that maybe flashing the computer might help, but I doubt it.
 

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Do you have the GMPP 3 BAR MAP sensors? If so, are they crimped, soldered or you have an adapter? If they're crimped, tear them apart and solder them. The crimping fails. If they're already soldered or you have adapters, or you don't have the GMPP MAP sensors, then do you have t-clamps on all of your IC piping? If not, buy these and replace them...T-Clamps from DDM Works. Otherwise it's time to start looking at more costly stuff like a hole in the IC, especially if its still OE and you're running more then 20psi of boost and it's an '07. Some have been known to split on the corners. Or a possible new turbo. OR......you need to adjust that red loctite bolt.
 

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Great suggestions so far. Physical issue with pressure leak or bad/broken sensor. Look everywhere for tubes/hoses/clamps for issues. I've had the cracked intercooler leaking on the end piece where you only can hear it under pressure but not at idle (I pressurized the system with an air compressor and PVC parts from Home Depot), broken turbo solenoid valve nipple, leaking hoses due to clamps. You get the idea. Many great threads on this site to continue your search (limp mode, turbo leaks, etc.). Spend the money for a good mechanic/shop to diagnose before flashing a tune or other costly parts replacements without putting your finger on the actual issue.
 

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Mine did something similar and it was the turbo solenoid having an issue. Broken studs on the part attaching those parts.
 

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Check the O-rings on the MAP sensors and the Manifold purge solenoid. If they are dry and/or deteriorated they are likely being bypassed and you are experiencing a 'lean' condition which causes exactly what you described - loss of boost, rough running, etc. We had quite a discussion of this issue last year around March. I wonder why more people haven't suggested that? Hmm? I had a code P0106 that showed up, but that may not necessarily happen. But if you look that up on the board it should get you to the discussion we had. Since that time and what I did - silicone greased the O-rings - my car has run perfectly, upon cold startup it idles down very quickly and full throttle boost is up around 20-22 psi. I have the GMPP upgrade on my '09 auto GXP with just over 50K miles.
grandpop07
 
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