Aight, I searched for "first gear boost", "low gear boost" and "boost problems" but did not find what I am looking for. I noticed that if I put the car in first gear, start to creep of the line to say 2500 rpm and then punch the throttle the car won't make full boost, infact it will go to 25 kpa and then it won't build even though the rpm's are climbing and thc ar is moving forward... If I get a clean launch however with minimal wheel spin and no bouncing it appears as though the boost will go as high as 60 kpa which seems like right for first gear.

Can anyone explain what gives with not building full boost in first if:
1. You creep off the line and then slam the throttle
2. You don't get a clean start and the car starts to "bounce" and "heave"
3. You lose traction, boost drops and won't rebuild

I just bought the car, I have 1000 miles on it, its an 06' S/C non-G85.

Thanks a lot, I really appreciate it,
Ryan

 

Hmm, I really hope this is just something stupid and that my belt isn't slipping, that's the only thing I can think of that would cause this to happen. I get full boost and 2nd and 3rd with no problems at all.

Thanks for helping me out,
RYan

 

That is odd. I'm not sure what to say about that. I have never encountered it. Does is feel different or is it just the guage that is different.

 

There is no audible supercharger whine, there is however whine in 2nd and 3rd, perhaps I have a loose belt? Is there an easy way to change the tensioner? I am unfamiliar with this aspect of our cars.

Thanks,
Ryan

 

in first gear to my knowledge, you dont get full boost due to the fact that you will never get traction if you did, alot of guys using hp tuners software limit boost even more in first gear so they have better launches

 

There is something wrong . You can call me if you want , I might be able to help you better over the phone 585-865-1832 , ask for Mike (10am-5pm est) .

 

Seems almost like traction control or something. I get 12 psi in first (I know its weird, but its true, traction in first is almost non exsistant for me on any road surface even a prepped race track) no matter what I do.

 

Directly from GM specs:
Boost in First Gear is disabled!!!!

You have to use an aftermarket tuner like HPtuner to enable boost in first gear. I can't imagine boosting in first gear, if I floor the car in first gear at any RPM the tires just break loose. You would have to get some serious traction mods before boosting in first would do any good.

 

Thanks for the heads up on the GM Specs, made me feel a LOT better!

Here are the GM specs for controling engine boost, I found this using Google:

Boost Control System Diagnosis
Circuit Description
Supercharger boost pressure is regulated under certain conditions to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) can limit boost pressure to 83 kPa (12 psi) or less. The PCM disables boost under the following conditions:

• When reverse gear is selected

• When the vehicle is decelerating

• If an intercooler pump failure is detected

• If the intake air temperature (IAT) sensor 2 becomes excessively high

• If the engine coolant temperature (ECT) becomes excessively high

• Under heavy load in first and second gear at engine speeds above 5,800 RPM

• When drivetrain abuse is detected

The PCM controls boost pressure by using the boost control solenoid. The boost control solenoid is a normally open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 99-100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum from the supercharger plenum to the bypass valve actuator to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. When the engine load is increased, the engine vacuum is decreased, causing the spring in the bypass valve to overcome the diminishing applied vacuum, closing the bypass valve and allowing the boost pressure to increase. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0-98 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve, and recirculating excess boost pressure back into the supercharger inlet.

 

do the boost bypass mod and see... also how many miles on the car? ask trix his bypass valve broke and he was losing boost til he did the bypass.

 

Thr GM spec shows no boost if beat on or high load above 5,800rpm not no boost in first.

If I hold 1st till say 2,800 and gun it the S/C whines boost goes up then the tires spin and I hit redline.

 

Learn how to launch your car.

 

When I first had my car I was confused about low boost numbers in first. I found that it did boost to a full 12 psi when I was *very* hard on first and ran it all the way through. A normal run up in first will not yeild full boost.

 

Launching wouldn't have anything to do with it concidering the clutch is all the way out before the tires start to spin

 

I'm having the same problem, but I have a cel to go along with it. Also the car feels different in 1st. Gonna have a friend who's a GM tech check it out.

 

power is managed to the first 2 gears. It get really annoying because second id a good pulling gear yet third pulls even harder. im getting my car dynoed and the power managemnt taken off of second gear.