What will cause BCS to lower boost?

[bigbro6785]

What will cause BCS to lower boost? For some reason my stock BCS would lower my boost from 11psi to about 6 psi. No boost leaks. Once I installed a MBC it held solid boost so I know it was caused by the BCS. What would cause this? Extremely lean conditions?

 

[Mr Peepers]

Make sure the BCS is hooked up as below. It sounds like you are only running wastegate pressure.

 

[motomattxxx]

Knock is what causes it. Boost gets pulled in an attempt by the ecu to reduce knock counts.

 

[GVR4592]

The ecu will lower boost when knock is detected. There might be other conditions that trigger low boost, but that's the only one that I know of. Do you have a datalogger?

 

[wret]

Your ecu will also pull some timing. This typically happens when you run low octane fuel. Even after refilling with good stuff, your ecu may hold back boost and timing until well into the next tank of fuel. If you disconnect the battery you can reset it but if you haven't addressed underlying causes, it will just happen again.

 

[bigbro6785]

Ya I have a logger I just havent had time to do a run with it. Ill try to get one tonight when i get off work. I have never ran anything less than 91 octane in the car so I doubt gas is the problem, and I had the bcs hooked up correctly. I now have a MBC and the car runs full boost it is still just really slow. Its frustrating. I thought the car was just running lean so i changed the fuel filter but that didnt help. Any other advice?

 

[boostnbuds]

vaccum leak at the bcs?

 

[Zenja]

You might be running lean, causing knock and pulling back a lot of timing to make the car slow.

 

[bigbro6785]

No there were no leaks. What else should i check to see if im running lean? I used injector cleaner and changed the fuel filter. Would my logger tell me if im running lean?