Boost lowerd

[Gs Dewd]

Okay I noticed this about a week ago. My car was hitting about 11psi of boost now all I am getting is about 6 psi in first then it goes to about 8 in second and tops off there. Other then that the car seems fine. This happened all of the sudden. No changes have been made to the car between the 11 psi it was pushing and the max of about 8 it is getting now. I am running 93 oct. gas and all maintenance has been done recently. Anyone have any clues what can cause this? What I have checked so far is the vacuum lines (which are new all of them) checked for boost leaks none found. Could this be the result of maybe the ecu seeing knock?

 

[timloomis]

yea knock will lower your boost.the ecu closes the boost control solenoid as a last ditch effort to stop detonation.retarded timing comes first though.8 psi is what the wastegate opens at so check on the wastegate actuator vaccuum line,your bcs,and hook up a logger to see whats going on.

 

[DSM90AWD]

A bit confused as to what setup you have from your profile. Do you have the 1G ECU and 100% of the electronics along with the 4G63Turbo swap in your 94 N/T?

If so tim is correct as the BCS will lower boost (if it is connected) by a few psi when knock is sensed

 

[Gs Dewd]

A bit confused as to what setup you have from your profile. Do you have the 1G ECU and 100% of the electronics along with the 4G63Turbo swap in your 94 N/T?

If so tim is correct as the BCS will lower boost (if it is connected) by a few psi when knock is sensed

Yes I have all the electronics intstalled with the swap and also a 91 ecu from a Eagle Talon Tsi

 

[Gs Dewd]

Okay here is what I have done so far. I unhooked the bcs and put in a mbc cranked it all the way in and still only getting 6 to 7 psi of boost. This is on a autometer boost gauge. I also logged the car and I am getting a high of 4 counts of knock and timing is around 30. Not sure what the problem is now. I am going to do another boost leak test to eliminate that. Any other ideals?

 

[timloomis]

make sure you hooked up the mbc right,and go both ways with the screw to make sure.sounds like a boost leak or a wastegate issue if the mbc is hooked up right.the bcs wont close with 4 counts of knock.

 

[Gs Dewd]

I looked at the log file again and posted it in the correct area. The 4 cnts was ealry on 1 time at like 1.6k rpm. I have the boost controller hooked up right it is a SBR mbc. I have the barb that is at the end of the screw hooked into the bov line and the one that is 90 degrees from the screw hooked to the wastegate. Guess I am going to be searching hard for a boost leak somewhere. Had one person tell me that the turbo is bad but I find that hard to believe considering it was fine one day and the next it wasn't.

 

[Gs Dewd]

Problem solved!! I found a vac lin going to the thermo vavle had ahole in it and also the waste gate actulator was stuck partially open thanks for all the help.