Boost Spike Explained?

1slowdsm · 08-22-2004

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** · 08-22-2004

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 · 08-22-2004

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** · 08-22-2004

Quote:

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 · 08-22-2004

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 · 08-23-2004

Quote:

Originally posted by ecoli@Aug 22 2004, 06:40 PM

Quote:

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 · 08-23-2004

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 · 08-23-2004

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 · 08-23-2004

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 · 08-23-2004

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?

1slowdsm · 09-14-2004

I dont know of any other way of tuning the boost controller. I've tried turning down/up the bleeder and I've tried turning down/up the coarse setting, but I still get the same results. I might have to try out Elites MBC and see if its the old boost controller or if its something else.

Jacek · 09-14-2004

Quote:

leme think it in bosnian

excuses, excuses..

mine old car use to spike 2psi and drop right away and that was with the original vacuum line setup.

1slowdsm · 09-14-2004

If it was only two psi spike on my car, I wouldnt really mind. But I have it set to 14 and it spikes at 19.