Boost Spike Please Help

[Mr_Boom]

Manual Boost Controller. Hooking it up on these cars is different than the zillions of other turbo cars on the planet (of course). Hooking it up to the stock compressor nipple will have you spiking like there's no boost control.

What worked for me was using the Turbosmart Boost T, hooking it to manifold pressure at the BPV line and ungating it.

+2...have the same set up with my MS3 and I don't see any boost over 18-20 psi.

 

[kooofie]

^^^^^ how do i do that?????? do i need to buy anything else....i want to boost to 20....just not over 22 how do i do that cause i see that i spike to 24-25 some times haha.........ungate it?

 

[AutoEuphoria]

I would also be interested to know the MBC install...you say you T'd off the BPV vacuum line...did that go to the inlet side of the MBC? Where did you hook the other side? What parts did you use for the install? I'm seeing boost creep, and if there is a way I can limit or eliminate that then I'd definitely want to check it out.

 

[jv92red]

Boost creep and boost spike are completely unrelated events.

Boost spike is initial boost overun but the major difference is that your wastegate is slow to open or not opening far enough which causes this overboost to happen. As suggested an MBC re-plumb can tune this out along with AP tuning.

If your boost is "creeping" your exhaust is free flowing to the point where the waste gate port cannot evacuate all of the flow through it once it has been opened - it then continues to impart exhaust flow energy to the turbine wheel thus spinning the turbo faster which = more unwanted boost. A MBC is worthless to controlling creep at this point as it has already pulled your wastegate open. The job of the MBC is over at that point where it opens the wastegate port. Want to get boost creep in check, look into porting the wastegate port, maybe throwing in a high flow cat for a little more backpressure, or you could go with a external waste gate set up. Or is there maybe a way to tune it out with an AP? - decreased target loads?

 

[AutoEuphoria]

Hmm...I might just try putting my stock midpipe in and see if that does something.

 

[coyfish]

I had really bad boost creep that was solved by a custom tune. Weird since I don't even have a DP. My A/F got too lean at around 5300 rpm, psi jumped about 2-3, and I got knock. Dangerous situation. Avoided WOT for months because of it. Now I don't hesitate .