Normally I'm running at about 16 to 16.5 PSI peak boost with no issues (when it gets cold it might jump to closer to 17psi). Have been for over a year. Relevent mods - Cobb stg 2, catless up, helix catted down, blitz intake. Haven't changed anything on the car recently. On the way home from Duluth, I began to notice my boost surging and then dropping repeatedly when at 85% to WOT (in 4th or 5th gear). It peaks at around 18psi and then drops to 10-12, then climbs back up and drops. It keeps doing this as long as I hold the throttle open that 85%-WOT. You can feel the power of the car surge and drop as boost rises and falls. I've now noticed this each day since. It only seems to be after the car has warmed up a lot (after driving on the highway for 10-15minutes). I originally thought it might be a hole/leak somewhere in the vaccum hoses between the turbo and the BCS, but I pulled and inspected them all and they look fine. Restrictor pill is in place. I reset the ECU, but the problem persists What else could be causing this. Could the BCS be going bad?
Just remeber that when you go with the gm sbc, you will NEED to get your car tuned. The bcs works differently than the stocker, so the boost map needs to be changed for the differences. Russ
you could try a different wastegate, it would be cheaper then a BCS. if you wanna try the wastegate, i have an extra one at home.
Lets stop calling it a wastegate...its a wastegate actuator...it would be pretty hard to change a wastegate...considering you would hafta change exhaust housings
Well, I checked the resistance on the BCS and there wasn't any, so that could be the problem. When I get home I'll put some current to it to see if it activates and how quickly. Maybe give it a good cleaning and see if that works. If it's not the problem I'll run a line from the compressor to the wg actuator and see if it holds boost to 7psi. Yeah, my first thought was about the GM bcs, but I would want to get a bunch of stuff along with it to make it worth getting a tune. And since I wasn't planning on spending $$$$, I'd prefer to fix my issue. Of course if I'm gonna start having to replace stuff, it's a good excuse to upgrade. Russ - How easy would a tune for the gm solenoid be?
I had the exact same problem about a couple months ago and it was a leak on the wastegate actuator. The nipple on the side of it had bent and created a small leak where air could escape.
