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Discussion Starter · #1 ·
Hello everyone.

This is my first post and my first question is this.
before the GMPP upgrade i was seeing a max boost of 17 psi, after, 17 psi. is this normal? I do have more pep and vigor so the upgrade took

I thought from reading I would see a higher boost psi, I'm not unhappy. I hope to get to a Dyno soon to verify HP & TQ but since I live in the sticks it will take a minute.

Next Mod planned is a HFC and a solo exhaust.
 

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Drive it more to see if you get a check engine light and you can go from there. Also the PSI depends on altitude and weather conditions, but since you're seeing the same boost, I am guessing this isn't the problem. If the tune was just copy & paste from another GMPP car is worthless.


I had the same problem, some members suggested several things, take a look :)

http://www.solsticeforum.com/forum/f43/gmpp-boost-125977/
 

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you need premium gas too...
 

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Discussion Starter · #4 ·
First I want to say Thank you and give a little more info.

in St. Marys Ohio we are 866 ft above sea level, I installed the 3 bar sensors and used the plug and play connectors, no soldering, used soap water to check for air leaks at the sensors and they are tight. The Dealer had my papers that came with the kit which listed the part number for the PCM flash. I did confirm with the mechanic which flash he installed and it was the correct flash.

I have an automatic transmission, I had emptied the fuel tank and filled it with premium from my local Shell station. The day I picked up my car from the dealer it was cold (45 degrees with low humidity.) and the engine did tach to 6200 rpm when I punched it.

I will be driving the car Thursday and Friday this week and it;s supposed to be in the low sixties both days and sunny, Sooooo I'll see if I can coax a bit more out of her, she's red with chrome so she has to go fast, Right?
 

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people here STRONGLY suggest that you use solder on the connections of a GMPP upgrade.
 

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A couple of things...

If you swapped the sensors (as you did) then you MUST have the correct flash, since the old firmware will not operate with the new sensors - you would go into limp mode as soon as you floored it.

The Automatic version of the tune limits torque (and thus, I assume, boost) more than the Manual version - 290hp/340lb-ft (Man) vs. 290hp/325lb-ft (Auto).

Having said that, you should still be getting more than 17lbs boost. Peak is reached in my car with my foot to the floor and accelerating through 50-60mph in 4th gear (mine's a manual). Try checking yours again at a similar rate.
 

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He has the connectors with pigtails that do not require soldering.
used soap water to check for air leaks at the sensors and they are tight.
I hope you mean at the clamps where the rubber and the metal tubings meet. At the in and out of the IC and also at the turbo.
 

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Discussion Starter · #9 ·
Again I Thank you all for the input.

To answer your questions
Yes, the correct down load was installed, the part number was included with the upgrade kit and the mechanic that did the flash confirmed upon my checking back with him. Yes, soaped for air leaks in the tubes.
I did all the research I could here on the solstice forum and the Cobalt site. So I was aware the of the HP/Torque differences between the manual and automatic. So I was expecting maybe 19 to 20 pounds of total boost and was surprised to still see only 17 pounds was, well disappointing. But I know I do have more torque cause the amount of tire dust left on the road is definitely more than before the upgrade.

I'll get to a local speed shop (50 miles from here) with a dyno and post my results when I have them. I need to do more homework so I more fully understand tuning. After I get my tune where I want it I plan to add a Solo HFC and exhaust, then back for more dyno work. I'm not looking for a street racer but do have a GREAT appreciation for the sweet reward of a responsive throttle and push back in the seat.
 
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