SaabCentral Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
164 Posts
Discussion Starter #1
ok so i have been cruising hte forums looking for ways to figure out why my car has been acting up. i just took it for a drive and at 120 km/h i was just into the yellow section with the pedal to the floor.

I did the test where you pull the vac line going to the wga. IF i read correctly when your bpc is working properly the needle should go all the way to the end of the red. When i pulled the line the boost stay 1/3 into the first section.
Did i do something wrong or does this mean i need a new bpc
 

·
Registered
Joined
·
3,009 Posts
just curious, year, model, miles, etc.
 

·
Registered
Joined
·
1,327 Posts
does it hit fuel cut at WOT with the line to the wga detached? if not, thats trouble somewhere other than the bpc
 

·
Registered
Joined
·
3,009 Posts
On a t5, those circumstances point to a bad boost preasure solenoid. I'd just put in a mbc+a. Many threads on this. Its cheaper, and would give you the freedom to crank up the boost.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #6
does the mbc go in place of the bpc.. i thought a mbc only went inbetween the bpc and wga
 

·
Registered
Joined
·
1,284 Posts
There are 3 lines coming out of the BPC. Turbo, Wastegate Actuator and a line to the cold Air intake piping. The lines themselves are engraved with an odd nomenclature. I cannot remember the lines names!! I think is I, W and R? I cannot rember out of the top of my head.

The MBC sits between the turbo and WGA. Therfore all the boosting and boost control between the turbo and the wastegate actuator is done by MBC, the BPC is effectively out of the loop except, for the lonesome line to the air intake. You can remove one of the two remaining lines (WGA or T line) and loop the other end into the opening from the line you removed. This loop protects the BPC in case you ever want to go back to it. (You need to remember where you put that extra line you removed however :) ).

The BPC test is to remove the the line from the BPC to the WGA. Go for a drive. With the BPC-WGA line removed, the turbo is out of control and free to boost. You should hit fuel cut off on every gear, 1st and 2nd included. If you still cannot redline and fuel cutoff, something other than the BPC is wrong, perhaps the WGA itself. You should be able to move the WGA manually side to side, parallel to the bumper. If you cannot do this, perhaps the WGA is stuck in some odd position.

There are some awesome posts on this subject, with pictures of the BPC and the lines to disconnect, etc.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #8
i did the test again and the fuel cut but the turbo was only making itjust into the red
 

·
Registered
Joined
·
2,297 Posts
If you pulled the line to your WG, then you should hit a fuel cut as there is no pressure to open the WG.

If you leave all lines on correctly, and pull the wiring harness off the back of the BPC, you will have only base boost which means your boost will be reduced.

Fuel cut area (1/3 into red) sounds in the vicinity of right. The guage is relative.

MBC will bypass the BPC.

Are you just tryng to see if the BPC is working properly? What were the symptoms that made you think the BPC was bad?
 
1 - 11 of 11 Posts
Top