Waylin22

Ok guys, so i had my motor rebuilt recently, new 10:1 diamond pistons, new cams, valves (still have the 60# ers)and went with a new intense 2.9 pulley. psykostevo and i kept the same tune on it as before so when i got the car back all fixed, We scanned it , no problems. So far I have these 2 codes a MAP/BARO Correlation code and a 02 sensor malfunction code. For some reason i am only boosting 8-10 lbs. I have tried to disconnect the battery trick, no change. Im takin the car to the dealer tomorrow to try to solve this mystery but i wanted some other opinions. Can anyone here think as to why i am seeing such low boost. Oh and i set my interceptor to scan boost to see if it was a faulty boost guage, no change either..

M88ArRamadi

It could be a number of things........
Check you vacuum hoses
check your by-pass valve (gasket and ensure it can fully close)
check your SC gasket
Check your IM gasket

Waylin22

That is a good idea, the gaskets are all new, as well as i tried a boost controller swap. all hoses connected too.

can a bad map sensor prevent the boost? if infact the one on my K&N CAI is effed up

Coblasts

Supercharger boost pressure is regulated to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) limits boost pressure to 83 kPa (12 psi). The PCM disables boost under the following conditions:

• When reverse gear is selected

• When the engine coolant temperature (ECT) is excessively high

• When drivetrain abuse is detected

• When the vehicle is decelerating

• If an intercooler pump failure is detected

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

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

The PCM controls boost pressure by using the boost control solenoid. The boost control solenoid is normally an 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 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. As engine load is increased, engine vacuum is decreased, causing the spring in the bypass valve actuator to overcome the applied vacuum, closing the bypass valve and allowing the boost pressure to increase. The bypass valve starts to close when the vacuum measures 250 mm Hg (10 in Hg) and is fully closed at 90 mm Hg (3.5 in Hg). When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0 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.

Waylin22

^^ wow very good info! My buddy gilbert and i thought also it could have been something with the solenoid, so we also swaped blowers. Pulled the rotors and snout off mine and put it into his spare blower.

bump?

Coblasts

I would take a look at the inter cooler pump ,see if there is flow.

Waylin22

Yeah ill check that out too. Wouldnt that throw a code as well though? One of the techs scanned my car and told me that there were some communication problems with the PCM...

memphisr24

Wait...you mean maf sensor on the intake?? If you do, no because if it failed, we would still be able to drive thanks to ve tables....

Map sensor however, which isn't on the intake, might be another issue....

Do the boost bypass "mod" and see if it will allow you to boost

Waylin22

^^ yeah thats my bad, it is MAP sensor not maf. Ill try the boost bypass mod tonight and see what happens. Good idea though