If you over boost you will not get a cel. You will however go into limp mode and push no more than 6 psi. It will stay like that til you clear the code or sometimes if you turn off the car for a period.

My guess you have a boost leak, not an over boost. Bad DV or a leak in your line somewhere.

However, if you are overboosting I would look to the N75 valve as the culprit.

And forget the boost valve for now. You need to figure out what is wrong with your car before you start adding stuff to it.

 

ok so i found out what is kinda going on with my car. now i need more help. the car is throwing a p1557 code. (charge pressure control positive deviation.)

where do i start?

i went around and tightened all the clamps on the whole car. throttle bodie the whole way to the turbo. and replaced clamps that broke. still does it. also was wondering... i got a forge motorsports dv. could the spring in it be too light? and be leaking threw there? and what color spring should i be running with the chip?

the boostvalve. says to bypass the n75. i might just end up trying that to see what it can do after my boost gauge gets here.

the car rips threw first and second the first time threw them, but then slips into a coma and doesn't want to go anymore.

what else could be causing it to leak? or what could it be?

thanks
bobby

 

It could also be a vacuum leak in one of the hoses. The vacuum pump drives the turbo VNT mechanisn via the N75 valve. "Charge pressure control" fault code is generally the ECU asking the turbo for a certain amount of boost, and the turbo failing to provide this. Then the ecu sees a problem and cuts into "limp mode" until the ignition is turned off and back on. The problem generally is the VNT mechanism sticking, which can generally be freed up by hand. It should move about an inch.

 

where is this located? so i can get my hands on it. i need this thing to run right! or should i just bypass the whole n75?