Boost Spike Explained?

[1slowdsm]

Okay...can someone on here explain boost spike and how to stop it? I have a TurboXS HPBC on and when ever I'm on the highway and I go from 5th to 3rd or 4th, the boost shoots all the way up to around 18 and then quickly drops back down. I have the boost set to 14-15 lbs, but it doesnt go right to the setting... :headache:

[Shane@DBPerformance]

Could be a lot of things. Boost leaks can cause it to happen. Internal wastegates reacting too slow. Not a big enough bleed hole in the boost controller to release trapped pressure can do it.

[Enes]

run your bov and vg off the intake manifold not of the turbo. block off the line going from turbo to the mbc from mbc to the vg.

The best setup i have seen working is from the intake mani to the bov t'd off to mbc and from mbc over to the wg. That has proven on few dyno runs i have vitnesed with boos spikes and then after they have moved it over it stabilized. Same thing hapend on mine too.

-E

[Shane@DBPerformance]

That has proven on few dyno runs i have vitnesed with boos spikes

Are you drunk or is that just your accent? ;)

Thats a good point also though.

[1slowdsm]

Right now I have my BC hooked up the way you said and it was spiking. I gotta do a boost leak test soon and if there is no leak, then I'm guessing its gotta be the wastegate. This is the same BC that Mike from QPR was using on his car, he sold it to me and now I'm getting boost spike. I have increase the bleed valve and see if that helps a little.

[Enes]

Originally posted by ecoli@Aug 22 2004, 06:40 PM
That has proven on few dyno runs i have vitnesed with boos spikes

Are you drunk or is that just your accent? ;)

Thats a good point also though.
leme think it in bosnian.. then rearange the order of words and then translate it into english...


you suck all

i mean you all suck..

;)

No i was in a hurry when i wrote that sorry.. and i do not drink alcohol so i can't be drunk..

-E

[john]

The running of the vacum lines shouldn't matter as I have run a mbc off my turbo for a while without it ever spiking. I have seen boost controllers cause it but not on such a low boost setting.

[Enes]

It could be in conjunction with more restrictive IC and IC piping because there would be more back preasure before the IC rather than after hence why it would raise and then fall back down to certain preasure..

-E

[Raptor]

Because of the 2 adjustments, it takes some time to do the tuning with that MBC. use the course adjustment as much as you can to get close then only use the fine adjustment as little as possible to get it set. It took a fair amount of time to get it set in my car then it was very stable for the entire time I had it.

[1slowdsm]

Right now the BC is still at the presettings, I havent turned the course setting up or turned the bleed up at all. It shouldnt be set to 14 lbs right away should it?