new intake - boost problems

[jbillakdsm]

Just put a Dejon intake on my car and now I'm having all types of problems with overboosting. I had my boost set at 15 psi with a Slowboy-designed MBC and now I'm getting like 25 lbs. I've tried adjusting it down, but nothing seesm to work. Do you think my MBC is stuck or is something else wrong.

 

[CyberEye]

did you hook everything back up right when you replaced the intake? Make sure everything is hooked up right. If it is, unhook the MBC and return it to stock via the BCS. If that fixes the problem, then your mbc is messed.

 

[jbillakdsm]

I pitched the old BCS a while ago and everything is hooked up to the new intake except for the charcoal line and I know that's not the problem. I'm going to recheck the lines to see if I got a kink somewhere.

 

[jbillakdsm]

I'm still having some problems with the boost. I don't think I'm having this much problem with boost creep beacuse I ported the wastegate to allow it to open the entire way and I ported and polished all the holes. I cranked my MBC out the whole way yesterday and I'm still staying around 16lbs with creep to 18 for a split second. How can I be creating 16 lbs of boost with basically no MBC in the way?

 

[JessesTalon]

With MBC's sometimes the spring (if its ball n spring) gets stuck on one of the threads and as much as you turn it out the spring is still cocked in there so maybe try take the screw all the way and make sure the spring is not caught on a thread.

Also try turning your MBC backwards... that should give you 10 pounds of boost... if it does not your MBC isnt working correctly... Good Luck, Don't overboost too much, let off the gas before it gets past 18-20...

 

[oldman]

Slow down and give us more details.

1. Describe the relations between boost and rpm. Let's make sure we are talking about boost creep.

2. Was the system creeping before the intake install. You obviously had creeping problem before, give us some history and time line.

3. So you are saying with the pressure source connected directly to the actuator, it hits 16 psi first and then creeps to 18psi?

Take your time and be as detail as you can, anything else you would like to add would be great.

 

[jbillakdsm]

I start noticing the boost getting high around 3500-4500 rpm when I'm WOT. The system will jump up to around 19-21, level off at 5 grand and receed down to about 18 by 5500.

It really wants to spike right after a shift if I get on the gas again. It got to around 23 and I let off the last time I was messing around with it.

It just seems like the MBC is stuck or my wastegate has decided to crap out on me, but I know both are good since they were replaced within the last 2 years.

The car did have a little trouble with boost creep right after I installed my 2g ported manifold along with the ported exhuast side on the turbo and the 2.5" RNR turbo-back with a high flow cat. I pulled the turbo back off and ported around the wastegate flapper to allow it to open fully and I never had any trouble after that.

I guess I'm just having trouble trying to figure out how my system could go from being perfectly fine and running 15psi all the time to now wanting to spike all because of an intake tube. I pulled my MBC apart since it's my own design and the ball and spring aren't catching on anything. They also are not rusted because I put a SS ball and spring inside. The rest of the MBC is aluminum so I can't see how that would be affected. It's mounted right back in the same place as before and gets plenty of air to keep it cool.

 

[oldman]

Let's try this again,

A. Boost spike = Boost shoots pass the setting first then settles back down to setting.
B. Boost creep = Boost hits the setting first then slowly increases with rpm.
C. All out boost = Boot shoots pass setting and never returns.
D. Others

Which one do you have?

 

[jbillakdsm]

I have C. It just goes right past where it should be set and stays there. I'm wondering if I have a crack or something in the line going to my wastegate.

 

[marcmsj]

I have C. It just goes right past where it should be set and stays there. I'm wondering if I have a crack or something in the line going to my wastegate.

i have the exact same problem. it was fixed for a while then just recently started happening again. first i thought it was the boost controller but even after returning all vaccuum lines to stock, same problem happened.

 

[oldman]

I have C. It just goes right past where it should be set and stays there. I'm wondering if I have a crack or something in the line going to my wastegate.

Are you sure? From what I have read, it sounds more like boost creep than all out boost but only you can make the judgment so let's assume the problem is all out boost. There are three things that can cause this,

1. A defective actuator not opening when suppose to.
2. A defective mbc delaying pressure from reaching the actuator.
3. A leak in the hose between the mbc and the actuator.

Let's do a test run to narrow things down a little.
Disconnect the pressure source from the mbc and connect it directly to the actuator then do a wot. If problem persists, you have a defective actuator. If problem fixed, either the line between the mbc and actuator is leaking or mbc is not functioning properly. You should know what to do from then on.

 

[jbillakdsm]

Found the problem. The hose going between my BOV and my MBC has a tiny hole in it that was being made by rubbing on the ABS mount. Replaced the hose and ground the edge of the mount smooth and now I have no problems at all.