intake install = crazy boost?

[MelloEclipse]

ok so my 97 gst was doing fine, only boost at around 11-12 psi with a 1g BOV, 16G turbo, boost gauge, and MBC.

i installed my intake last night, today i took it for a spin and boosted at 22psi. not good i know. any suggestions as to why this is happening, boost leak test proved nothing out of the ordinary, i even tried cranking the MBC way out to see if that was it, and nothing.

Kinda at a loss right now, and trying to keep it out of boost til i figure it out.

 

[DirtyBirdRacing]

Thats pretty odd. Are you sure that you tightened everything back up and that you didnt knock anything off during the install? Know it seems like a stupid question but it happens you know.

Bill

 

[MelloEclipse]

yea i checked, rechecked, and tripple checked everything to make sure.

 

[DGajre777]

11-12 psi is the actuator pressure on the T25 without a boost controller connected. What are the hoses going to your boost controller? It may be because you didn't really have the boost controller hooked up before and now you do. Do you have a ball and spring type boost controller?

 

[RichCaccese]

i had a similar problem. it turned out to be the wastegate nipple was pinching against my custom 3" intake pipe. it was causing a slight leak, and the first time i got into boost with the pipe on, it flew way past the desired 20 lbs. i'm pretty sure i blew out the Joe P MBC.

well, first check to see if the nipple it making a clearance issue with your intake pipe. i simply bent the nipple down towards the fan very carefully with a very small diameter screwdriver. DO NOT try to bend it with pliers, you want to bend it from the inside with a small pick or driver so you don't end up pinching, or even breaking the nipple.

disconnect the MBC entirely. run the wastegate directly to the intake manifold just to make sure your running the stock wastegate pressure and to verify it's working properly (11 lbs on my evo3). borrow a friends working MBC, and re-route the lines back the way they were to see if you blew yours out as well. best of luck.

 

[MelloEclipse]

ah see i wondered if it was a 'blown' MBC as well...but wasn't sure.

I think i just may replace the MBC all together, since i don't know what kind is on there now as it came with the car when i bought it. I guess i'll just pick a new one up sometime and just take it easy for a while.

 

[brisvr4]

I had this happen to me when I removed my old stock intake and swapped it for a straight unit.
I was running approx 18psi on the stock setup and when I installed the new intake pipe my boost shot up to around 26psi .
The only thing that I could put it down to was the possibility that the new intake was letting way more air into the turbo than the old setup could manage.

 

[MelloEclipse]

I had this happen to me when I removed my old stock intake and swapped it for a straight unit.
I was running approx 18psi on the stock setup and when I installed the new intake pipe my boost shot up to around 26psi .
The only thing that I could put it down to was the possibility that the new intake was letting way more air into the turbo than the old setup could manage.

so i assume you just backed the MBC down until you were back to 18psi?

i'm going to assume i have the same problem, just that my MBC is fried.

 

[RichCaccese]

make sure you find the problem before you install another MBC. "taking it easy for a while" isn't really going to fix anything.

 

[MelloEclipse]

i say it's the MBC because it's hooked up right, however twisting it either way (all the way in, or all the way out) doesn't make any change in boost.

any other suggestions besides that? it just seems to be the only thing that it could be.

 

[brisvr4]

I did adjust the mbc but not all the way down to 18psi. It's been running nicely at 22psi for the last couple of months now

Have you removed your mbc and taken it apart to check the ball and spring isn't binding?
Double check the wastegate nipple connection too.
You can also try bypassing the mbc and going direct to the cooler piping to run wastegate pressure only. Try all of that before you toss money at another mbc.
Good luck with it mate

 

[numlock666]

lets look into the science of how a MBC works. Your Internal Wastegate Actuator moves when it "sees" boost (8-11lbs) how the MBC works, it blocks off boost from getting to the actuator, keeping it from opening your wastegate, thus your boost rises until there enough pressure to push back on the ball and spring in the controller to get to the actuator. the tighter you turn the screw (right) on the MBC, it pushes down on spring more, compressing it. Which then seals up against the inlet nipple more and require more pressure to push it back and allow the actuator to see boost. It basicly blocks boost from getting to the actuator until a certain amount it achived to push the block away.

So to tell you whats wrong, make sure you have your MBC hooked up right (boost source = nipple directly opposite of boost adjust screw) Try taking out your MBC and go strait from the boost source to the Actuator, it should max your boost at 8-11 lbs.

 

[TSIMonsteR]

assuming it is a ball and spring MBC... I don't see how it can be "fried". I STILL think you have a bad/leaking/kinked line somewhere.

 

[DirtyBirdRacing]

assuming it is a ball and spring MBC... I don't see how it can be "fried". I STILL think you have a bad/leaking/kinked line somewhere.

+1

Try checking and replacing the lines that go to and from the MBC.

Bill

 

[oldman]

i had a similar problem. it turned out to be the wastegate nipple was pinching against my custom 3" intake pipe. it was causing a slight leak, and the first time i got into boost with the pipe on, it flew way past the desired 20 lbs.

This is a very common problem for 14b/16g with 3" intake pipes. Same thing happened to me years back, ended up having to bend the actuator fitting for clearance. Mello, have you looked into this?

 

[RichCaccese]

This is a very common problem for 14b/16g with 3" intake pipes. Same thing happened to me years back, ended up having to bend the actuator fitting for clearance. Mello, have you looked into this?

heh, i think he totally ignored it. simple fix.

 

[MelloEclipse]

i haven't even looked it in 2 days but in the morning i'm checking the actuator fitting for clearence... and i didn't ignore that, but you know how you read things and they just don't register sometimes? that happened. i've been out of it a few days with everything, maybe i'm going insane.

 

[TSIMonsteR]

This is a very common problem for 14b/16g with 3" intake pipes. Same thing happened to me years back, ended up having to bend the actuator fitting for clearance. Mello, have you looked into this?

That is what happened to mine. I bent mine and switched to some ultra thick vacuum line and it solved me issues.