Wayy tooo much boost!

[Ultimatedsm]

Hey guys, I finally got my car back and passed emissions. I did a 1g in a 2g with a 1990 motor. Now, I think I hooked up everything properly, it runs perfect. However, when i punched it today, the boost hit 18 psi and popped an intercooler pipe off. I have the MBC set all the way to the minus, it should be doing like 12 psi. What the hell is going on??? I don't want to blow another motor . It was really fast though . Could I hooked up the vacs that go to the MBC backwards? Or is it something else?

 

[Ultimatedsm]

Alright, I flipped the MBC vacs around and now I get 12 psi. However, when I get 12 psi in 2nd and go to 3rd right away, the boost takes forever to come on. But if I do a roll on in 3rd at 3000 rpm, it kicks in right away. now whats going on??? help pleaseeee...

 

[oldman]

when I get 12 psi in 2nd and go to 3rd right away, the boost takes forever to come on. But if I do a roll on in 3rd at 3000 rpm, it kicks in right away. now whats going on??? help pleaseeee...

Is your BOV recirculated? Which AFPR do you have? at what base setting?

 

[Ultimatedsm]

The BOV is connected in the stock position Vac hose. FPR is at the stock setting. The BOV sounds way different though. Before it used to make a loud PSSSSST, now it sounds more like a rally car BOV. Its a TURBOSMART BOV, the one with the slits. I hope it isn't broken or something.

 

[hellotbone]

Hahah you actually passed emissions

Sounds like a BOV problem or your MBC have a good look do a boost leak check.

 

[oldman]

The BOV is connected in the stock position Vac hose.

I'm not familiar with the Turbosmart BOV, just make sure it's recirculating back to the intake pipe. Venting your BOV will cost you spool up time between shifts.

FPR is at the stock setting.

Do you mean you have the stock FPR or you have an A(adjustable)FPR with base set to 44psi. Astock FPR will be overrun by the 255 causing you to run rich during idling or part throttle, ie. between shifts.

now it sounds more like a rally car BOV. Its a TURBOSMART BOV, the one with the slits. I hope it isn't broken or something.

Do a leak test to make sure everything is in order.

 

[Ultimatedsm]

Alright, I switched the J-pipe Vac and the wastegate vac around on the MBC, now I get fine boost between shifts but the damn thing goes to 20 psi, if not more. The MBC is set to all the way to the "minus" Its a Turbosmart boost controller. I also noticed another thing, my BOV isn't opening. I reved the are in neutral redlined it a few times, and no venting. The BOV is hooked up to the big Vac port in the front of the intake manifold. These are my mods:

1990 JDM motor in a 1995 Eagle Talon TSi
Walbro 255 LPH HP /w FPR
S-AFC, Mega Flow HKS intake
14B turbo.

my "map sensor" or MDP is just dangling right now because I have to weld a piece on that 1g intake manifold on the top.

 

[Ultimatedsm]

Oh forgot to mention, 3 inch exhaust with 3 inch highflow cat and striaght through muffler.

 

[oldman]

The BOV is hooked up to the big Vac port in the front of the intake manifold. These are my mods:

Where is the RECIRCULATION tube connected to, I'm not talking about the vac line. A picture will clear it all up. If you're not sure what I'm talking about it's ok to say so.

my BOV isn't opening. I reved the are in neutral redlined it a few times, and no venting.

You can't build boost in neutral so there isn't any pressure air to blow off.

Walbro 255 LPH HP /w FPR

I'll attemp the question for the third time,

Do you mean you have the stock FPR or you have an A(adjustable)FPR with base set to 44psi.

Again if you're not sure just say so.

Alright, I switched the J-pipe Vac and the wastegate vac around on the MBC, now I get fine boost between shifts but the damn thing goes to 20 psi, if not more. The MBC is set to all the way to the "minus" Its a Turbosmart boost controller.

Do a test run with the mbc bypassed (connect the pressure source hose directly to the actuator), If you're able to boost solidly at 10-12 psi, either the mbc is bad or hooked up incorrectly. If problem persists, either the actuator isn't opening, boost leak preventing actual pressure from reaching the actuator or you have boost creep.(hitting initial boost setting and slowly CREEPS up as rpm rises.

 

[Ultimatedsm]

The BOV is vented not circled (I had a T-25 and notice no problems before and I had a 60 trim turbo noticed no problems either with spool up)

You can build a 3-4 psi in neutral demanding how small your turbo is. When I had the T-25, the BOV slits would open and vent air, but now I tried it again, I hear a wierd rally car bov sound but no venting is happening. It shouldn't be sounding like a rally car, should be a PSSSTTT a loud one.

The FPR is adjustable but only upping pressure from stock not lowering it and its in stock base fuel pressure. I dont know what brand it is, it was done by a performance ahop awhile ago when I had the 60 trim. It was put on specifically because of the 255 could overrun the stocker.

 

[psychlow]

The BOV is vented not circled (I had a T-25 and notice no problems before and I had a 60 trim turbo noticed no problems either with spool up)

Be that as it may, I almost gaurantee that's your between-shift spool problem, unless your BOV isn't releasing for some reason.

You can build a 3-4 psi in neutral demanding how small your turbo is. When I had the T-25, the BOV slits would open and vent air, but now I tried it again, I hear a wierd rally car bov sound but no venting is happening. It shouldn't be sounding like a rally car, should be a PSSSTTT a loud one.

You're right, you can build boost in neutral - I did it all the time on my 16G (got 10PSI). You should have a bit of a blowoff.

The FPR is adjustable but only upping pressure from stock not lowering it and its in stock base fuel pressure. I dont know what brand it is, it was done by a performance ahop awhile ago when I had the 60 trim. It was put on specifically because of the 255 could overrun the stocker.

This is the B&M CommandFlo FPR, and it's junk, sorry. It still gets overrun, just like the stock unit, because it's actually the stock unit with a fancy cover on it that lets you raise fuel pressure. If it's set to stock, it's just like having a stock FPR on the car.

 

[oldman]

The BOV is vented not circled (I had a T-25 and notice no problems before and I had a 60 trim turbo noticed no problems either with spool up)

I will not comment on whether you can FEEL a problem with venting and focus on facts in oder to help you diagnose the problem, what you choose to do with your car is your decision to make. The fact are,
1. You're loosing metered air running rich between shifts, if you log you will probably see this.
2. You're loosing the recirculated rush of air into the intake pipe which will help keep your turbo spooled between shifts.

You can build a 3-4 psi in neutral demanding how small your turbo is. When I had the T-25, the BOV slits would open and vent air, but now I tried it again, I hear a wierd rally car bov sound but no venting is happening. It shouldn't be sounding like a rally car, should be a PSSSTTT a loud one.

If you're abe to build boost and you don't hear the blow off, this can be serious because of compressor surge. Might be a good opportunity for you to try out a new BOV that can be recirculated.

The FPR is adjustable but only upping pressure from stock not lowering it and its in stock base fuel pressure. I dont know what brand it is, it was done by a performance ahop awhile ago when I had the 60 trim. It was put on specifically because of the 255 could overrun the stocker

Sounds like you have the B&M Command flow. If so, it will not solve the overrun caused by 255 because it still uses the stock fpr return orifice. You can easily verify this if you don't know the brand of the fpr by installing a $30 fuel pressue gauge on top of your fuel filter and check the base pressure.

From what I have gather so far, I suspect the mbc was hooked up correctly before and that's why you have all out boost after you reversed it. I think your lag between shifts is probably caused by one or combination of the followings.

1. Defective bov possibly causing compressor surge.
2. Vented BOV.
3. POSSIBLE fpr overrun.

These are just my opinions, again not here to tell you how to run your car so take my suggestions for whatever you think it's worth. Do take note that as you move up the HP ladder, every wrong turn can cost big $ so it's important that you do it right. Good luck.

 

[oldman]

Damn you psychlow , I had to take a phone call half way through writting my post. I got to learn how to multi task.

 

[1fast97gsx]

how about just starting with the easy stuff first ... do a boost leak test.

 

[Ultimatedsm]

I am going to try a boost leak soon, another thing I wanted you guys to know is lets say I am crusing at 40mph my Vac hg is around 12-10 or so, than all of a sudden it drops to like 2 and the car gets a little studdery. Than I come up to the light, the Vac pressure is normal again. However at idle it goes from 21hg than to 15 hg and jumps a lot and goes back and forth. So now after sitting at a light I start driving again, I am cruising at 40 mph Vac is at 10ish than it drops again after 15 seconds to 5hg again. By the way guys thanks for answering my questions, you guys rule!!