uh oh, boost creep woes?

[SupraCorwin]

Hey there, i recently started having a horrible creep issue, I searched the forum and saw a few threads about a 1-3 psi creep but this is different.

If I go full throttle after I shift my psi will constantly rise a few psi a second and not stop till I take my foot off the pedal, I saw it almost hit 20 psi and it wasn't boosting yet, just running off normal engine power.

So if I only go half throttle my aftermarket boost gauge will hold at about 0 psi/vac for a few seconds then boost up to 11 psi on the dot and stay there just fine like it should, and at that point i can hit it full throttle and it will still stay at 11 psi and my wastegate opens more.

Anywho I have a BIC ddp, 2.5" intercooler, full 3" exhaust with 1 cat, hks ssqv BOV and no 3000 pipe and a manual boost controller from turbosmart.

I never noticed this before i put the MBC in so i'll take it out and see what happens, thanks for looking.

 

[jimi87-t]

It's because you are running a MBC, get rid of it.

 

[SupraCorwin]

Took out the MBC, didn't make a difference. My wastegate was shimmed out like 6 washers on each bolt before i bought it so i don't know for how long. Would a streched wg spring have the same symptoms? And if so would re-shimming the wg a few washers be a temp fix untill i can get a new spring?

 

[jtran8]

Why use mbc and shimming wg at the same time lo ? shimming the wg will limmit your wg openning and caused it boost creep . electronic boost control is good MBC is ok , you need to remove all those washers off your waste gate then reintall MBC and readjust it .

 

[SupraCorwin]

Sorry I should have been more clear, when i bought the car i noticed the wg was shimmed with 6 washers, later that same day I took them all off, but what i was saying is damage was already done at that point. Now currently 3months later i installed the MBC and noticed the creep problem, although the creep could have started when i installed my spearco replica IC a few days before the MBC.

So recently i have upgraded my IC, installed a MBC with about 1 foot more hose length then was there previously. And the possible damage from the previous owners wg shimmage.

Any clues to my creep?

 

[crazyintentions]

stock ct-26 with manual boost controller, if you raise teh boost more than 11 to 12psi it will spike due to the fact that the spring on the internal wastegate is weak. Try to set the boost at 10psi and see what happens if it still spkies then replace your mbc imo.

 

[SupraCorwin]

As per my first post, the psi creeps up before i even start boosting, it can get as high as 20 psi with out triggering fuel cut, this only happens when I start a gear at full throttle.

If i start a gear at half throttle the car will boost after about 3 seconds then I can go full throttle and it will stay at 11 psi (what my MBC is set too) and not creep past.

In example: I shift out of first gear, go into second gear and slam the pedal to the floor, my psi starts rising fast and no extra power kicks in, i got close to 18-20 psi (iv'e only done this one while testing systems) and i can hear a screaming sound from the engine like a high pitch forced air leak (sadface) if i stay on it i'll make it most of the way through that gear with out feeling boost, but i stopped because of the sound.

I do a pressure test to 15 psi, no leaks. I go back out and shift into second gear, but this time i start at only half throttle, it takes a few seconds at 0 psi/vac then my car boosts to 11 psi, i stab the gas to full throtle it stays at 11 psi no screaming, and then at that point the wg opens.

I took off the MBC completely and still have the same issue at full throttle, and boost at half throttle i hit 10 psi solid.

Uhg