Rep Power: 380

I'm up and running with my turbo but need a little help with vacuum. When my kit was put on, the guys used a vacuum block on from the brake booster vacuum line. On the dyno, we immediately knew I was getting compressor surge. So the question was "is the BOV even working?" I knew it was getting some vacuum, so I switched it out and the same thing occured. Next, my ABS light came on. Clearly that line wasn't ideal for vacuum. Next I noticed that when I'm in boost, if I need to slam on the brakes, they're hard as hell for a few seconds. Obviously, I need a new vacuum source. Where do you guys pull your vacuum from?

 
Rep Power: 328

exact same place as mine. I get some compressor surge at lite throttle/low boost

 
Rep Power: 242

Rufus, is that a Full Race logo I see?

 
Rep Power: 380

It is. Everything is within a mile of each other down here in AZ

 
Rep Power: 380

No ABS light on? On the block bottom I have the middle 3 plugged and the far left one going to BOV and the far right one to my wastegate. Maybe I have a leak....


EDIT: I see no ABS unit on your car. lol

I still have a very hard brake pedal during boost...

I'm at 175whp on 5.2PSI

 
Rep Power: 328

ABS light came on when it was strapped to the dyno?

 
Rep Power: 328

hard pedal under boost... i bet that you/they removed the check valve in the line. And they /you shouldnt have

 
Rep Power: 380

No after driving it for a bit, just after the dyno. It went straight from the shop to the dyno (wasn't on the road at all)

 
Rep Power: 380

I didn't. Hell, I thought that was all internal anyway. I'll ask to see if I can get it replaced.

 
Rep Power: 328

Just a guess would be they somehow damaged awheel speed sensor or they put it into a ABS stop while on the dyno and it malfunctioned

 
Rep Power: 328

The check valve is mid way between the intake manifold and the brake booster, and its not visible from the outside. but you can feel it if you squeeze the hose

 
Rep Power: 263

I'm turbo, w/ abs, & I have my vac manifold just like that.

I have no abs light, turbo works fine, brake pedal is fine, & no vacuum problems?

What do you mean by compressor surge?

 
Rep Power: 380

I think we figured it out at lunch. You're right about the check valve. The guys suggested removing the check valve from it's current location and putting it before the vacuum block.

 
Rep Power: 380

Without enough vacuum to get the BOV to open the excess air is released back through the turbo, which can be very bad for it.

 
Rep Power: 351

Yeah, you want the vac manifold sourcing vacuum directly from the intake manifold. Those guys should know that....

 
Rep Power: 267

THe way i understood compressor surge is that when the throttlebody closes and there is to much pressure between the turbo and the TB and the pressure doesnt have anywhere to go and it tries to go back out the turbo which causes the compressor blades to spin the wrong direction. It can be bad cause when the Tb is opened again the turbo will try to spin the right direction again and it can stall the turbo and possible hurt it. Thats why you use a BOV to try and eliminate compressor surge. I think it can also be caused when the BOV is too small for the turbo and it cant release enough of the pressure. Forgive me if this isnt right its been a while since i looked this up and im still on pain killers from my surgery.

 
Rep Power: 351

That's pretty much it. Boilermaker snapped his shaft from using a shitty bov.

 
Rep Power: 263

oh ok.....so it's the BOV not doing it's job........learn something new everyday! I'm glad dezod supplied me with an awesome BOV.....I don't think I'd ever have to upgrade

 
Rep Power: 380

Well I thought I'd at least try their suggestion and move the check valve to the other side of the vacuum block, although I coudn't logically think of a reason why it would work any different, and it didn't change a thing. I'm going to try Andy's suggestion and T off the vacuum line above the brake booster vacuum line on the IM.

 
Rep Power: 380

So the "check valve" that Honda had in there wasn't really a check valve.. I could see right through it.


We put a regular check valve in and the brake assist is back. The BOV is opening but I think it's just a shitty one. I'm ordering a Greddy.