too much boost! help

[blktalon]

ok, i installed a 2.5" exhaust, 16g with intercooler piping and greddy bov. already had k&n filter and autometer boost gauge. the problem is when the boost starts to build, it goes to 22psi and above as the rpm increases. the stock t25 turbo always spooled to 15 psi and held there. the boost nipple for actuator is in the same place, so i removed all control and hooked the nipple to the actuator direct. no difference at all. what is going on? i checked the wastegate actuator and it starts moving at around 15psi. is this about right? any ideas will be appreciated---thanx

 

[my_gst95]

Does it hit a certain boost right when you WOT it and then slowly climb after that? If that's the case, it sounds like you have creep. But creep usually happens if you have a full 3" exhaust with no porting on the o2 housing side or a fat leak (cutout). Have you tried hooking up a mbc to the system if you can keep the boost level down?

my_gst95

 

[blktalon]

Originally posted by my_gst95
Does it hit a certain boost right when you WOT it and then slowly climb after that? If that's the case, it sounds like you have creep. But creep usually happens if you have a full 3" exhaust with no porting on the o2 housing side or a fat leak (cutout). Have you tried hooking up a mbc to the system if you can keep the boost level down?

my_gst95

the boost gauge looks like a tach. as rpm increases, so does boost. i haven't run the motor past 5k rpm because by then the boost is at 24 psi. i have a mbc but i think they work by bleeding pressure off to increase boost. i'd be happy if i could get boost to stay at 15 psi. i'm afraid with stock injectors and pump that somethin bad will happen!

 

[Erok]

try reversing your boost lines, you might have them reversed, start with your mbc screewed out as far as you can, floor it, if it goes straight to 30psi, or twards it then you probly have the boost lines reversed, so switch order of the lines then try it with the screw out as far as posible, then slowly screw in screw little by little and see what you are running, when setting your boost, dont just floor it and see what it spikes at in first gear, get up to about 30 mph put it in 4th gear and wot it, boost will slowly build and when it quits building then that will show your boost, sence it is in a higher gear and at a lower rpm you wont spike or get boost creep as easy. that is how you are spose to set your boost, good luck

 

[rv7builder]

Do you have full range of motion on the wastegate when the actuator does its thing? I have a PTE50 turbo and the actuator rod and the wastegate lever don't line up. This causes some binding. I haven't noticed any ill effects yet, but I'm watching for it. If something on the rod is binding, that could keep your wastegaste from opening fully and would probably result in the creep you're seeing.
Good luck.

 

[blktalon]

it seems like the wastegate is opening and then the turbo overcomes this minor annoyance and spools up until fuel cut. I ran 3rd gear to 5k rpm and saw 25psi boost until fuel cut shut it down. Impressive power but not very manageable with stock fuel system. I guess i'll add a spring to wastegate lever in hopes of opening sooner and farther, just to see what happens.

 

[~laser_craver~]

i think u have the common case of boost creep my freind, port your o2 sensor housing or put and external dump on it, or u have to get a external wastegate and rip out the flapper and weld a peice of ss ova da hole

ryan