Boost Creep Hell!!!!

[tsigeoff]

I figure I'll post this in here....it has stumped me and 6 of my buddies.
I get major league boost creep! I have a homemade dual stage boost controller. I run the stock 10 lbs, then go to 20 when I flick the switch, so I use the stock wastegate and boost solenoid. I have tried three different wastegates, so I'm beginning to think that's not the problem...I have redone all my vacuum hoses, everything. I've even taken off my boost controller and I got to 10 psi, then at about 4500 rpms, it shoots up to 25! The same goes when I have the boost controller in. I have no clue why it is doing this.....I changed my bov a while back and ever since then it did it. Since then I put the stock one back on and sold that one, so I thought it would be ok now. I'm stumped really bad. I used to have perfect boost, now I'm afraid to get on it, cause I hate running 25 psi. Not sure if it could be a cracked manifold or o2 housing. Any suggestions would be appreciated. NEED HELP PLEASE!! thanks

geoff

 

[Tra2xx]

What exhaust/turbo/ect mods do you have?

If you are stock, first of all you shouldn't be running 20psi, let alone having it creep after that... but more to the point check all vacuum lines.

 

[Tevenor]

What do you mean you used '3 different waste gates'? Are you talking about the actuators? That does absolutely nothing for you.

Boost creep is caused by the pressure differentials across the turbine vs the pressure differentials across the wastegate.

 

[tsigeoff]

here is a site of my car and mods. I thought boost creep was caused most of the time by the wastegate acctuator sticking close. Not sure exactly what the problem is....

http://www.njprecisionimports.com/geoff.html

 

[JET]

First of all, take off that boost controller you made and put the stock one back on. I am willing to bet if it still does it that the boost line going to the stock BCS is not correct (or you have a leak). Boost creep is caused by the wastegate not flowing enough. Whether it is malfunctioning and not opening (sounds like your case) or the opening isn't big enough (usually a slower creep).

 

[cleaning]

Yea take off the home made boost controller. This may be the cause of all your problems.

If you don't want to take off the homemade unit then check that for leaks in this unit.

It terms of it being a bov or diverter valve issue, check the function of whatever you using for cracks or anything that may lead to a leak or rip.

 

[tsigeoff]

I took off the homemade boost controller and went over all my vacuum lines. I have the dual stage setup and I thought I may have switched one by accident when I replaced them all a while back. I put my old wastegate on and it does regulate bosot in 4th and 5th gear. It's a soild 10 psi. but in the lower gears it creeps like hell around 4500 rpms. If I had a crack on my manifold or 02 housing, could that be the cause....I heard though that would stop be from building boost? I'm supposed to leak test it tomorrow, so I hope I found the stupid problem.

 

[RipperXX]

this is why i want to pay $80-100 for a MBC...

hope you figure it out cause i can't think of a damn thing that would do it unless it just cant get rid of the excess pressure fast enough... since the engine is turning higher revs in lower gears i would think that was it but you said at the same rpm in low gears as high so #### if i know...

 

[candela]

Your posts allways give me a nice laugh ripperXX:laugh:

 

[Ludachris]

First question - what size is your flapper valve? Did you get the 34mm upgrade on that 16G turbo? Is your turbine housing ported? If not, and you have a full 3 inch exhaust, you might not be able to cure your problem.

When you say you changed your wastegate, please explain exactly what you replaced... if it was the actuator, you're not really changing the actual wastegate. The arrow in the attached image is the actuator.

 

[Ben K]

Originally posted by Tevenor
What do you mean you used '3 different waste gates'? Are you talking about the actuators? That does absolutely nothing for you.

Boost creep is caused by the pressure differentials across the turbine vs the pressure differentials across the wastegate.

I love it when Sean talks about pressure differentials, it just sounds so technical.

Ben

 

[Isotta91]

get an external wastegate. my buddy had horrible boost creep, he got the ext. wastegate from hks and now his car is running beautifully

 

[Tevenor]

Originally posted by Ben K


I love it when Sean talks about pressure differentials, it just sounds so technical.

Ben

....and it almost sounds like I know what I am talking about, doesn't it Ben?

You know you want me, don't you..... BWahahahha.

 

[Ben K]

Originally posted by Tevenor


....and it almost sounds like I know what I am talking about, doesn't it Ben?

You know you want me, don't you..... BWahahahha.

It definitely sounds believeable.

You sexy man, I want a ride around one of those twisty track things in your car. I think they are called autocross or something.

 

[Slowboy]

Boost creep is really simple. The WG hole on the left cannot flow the amount of exhaust through it to regulate boost... It is about .9" in diameter. The opening on the right is 1.125" and can flow an adequate amount of exhaust for up to approximately a 46 trim size turbo.

Any bigger than that, a 1.25" opening is needed. However, this size of an opening can create a problem for 16g style WG actuators. They do not have a stiff enough spring to hold the door shut because of the amount of pressure placed on the larger flapper door.

Hope the pic helps.

Regards

Mike Huml

 

[markGSX]

holy crap 10 creep to 25 PSI.. that's more than creep, that sounds like it's not regulated at all

 

[pneumo]

How old is your turbo? I've seen plenty of old turbos on 1G's that have the wastegate pivot bushing slid out of the housing slightly, which won't let the wastegate open fully. wish I had a picture.

 

[DrZiplok]

Originally posted by pneumo
How old is your turbo? I've seen plenty of old turbos on 1G's that have the wastegate pivot bushing slid out of the housing slightly, which won't let the wastegate open fully. wish I had a picture.

Like this?

 

[pneumo]

YES!!! That's the one! Nice of you to make the bushing white for clarity. The bushing I'm talking about is the white thing in the upper left in the picture. As the turbo gets older the bushing creeps out, and the wastegate door moves over, too. Eventually the wastegate starts hitting the inside of the housing and can't open enough. It also won't close completely, leaving a crescent shape opening, which delays spoolup. It can be fixed by tapping it back in with a hammer. Be careful, it should still stick out by 2 - 3 mm. The best way to do it is to remove the O2 housing so you can see when the wastegate is centered over the hole.
Thanks Dr. Ziplok!

 

[tsigeoff]

when I say I replaced the wastegate, I mean the actuator. I leak tested the car the other day and I was leaking out of my bov flange. I replace the gasket and still the same shithappens, but not as harsh. here is the deal now....

I floor in first 1st 3 gears, it creeps from 10 to 20 psi at exactly 4000 rpms. I can hear the engine starting to really pull then the boost shoots up! In 4th and 5th gear, it regulates boost fine, a perfect 10 psi.

like I said before I have a dual stage boost controller setup. I have a homemade boost controller with a bleeder valve....I have an engaging switch, which runs off the stock boost solenoid. When I flick the switch it turns off the stock boost solenoid and allows the air to be controlled by the boost controller. Here is another thing I notice....My boost controller bleeds air at idle. When I flick the switch to run off the boost controller, the air is supposed to stop bleeding. Now..it bleeds air with the switch up or down, so there has to be something wrong, plus my vacuum is 8-9. It used to be 19-18! it's really pissing me off.

I have a plain 16g with a 7cm exhaust housing. the turbo is about 30,000 miles old, but it's been well maintained and has zero shaft play. I also have a ported 1g manifold, and ported stock 02 housing with dump tube.

THis whole thing is pissing me off. I used to have perfect boost control. I would flick my switch and know what I was running all the time. I felt safe, but now this shit is bothering me. I have no clue what it is, It started after I put the type s on, but that is long gone now. I would say about 4 months now it's been like this and so far, I can't figure it out.

 

[kpt4321]

Remove the whole boost control setup for a while, in order to test the rest of the car. The problem here is that the homemade system is just another variable, which complicates things too much.

However, do NOT hook the whole stock system back up. Just run a line directly from the intake manifold (or any pressure source, like an IC pipe) to the WGA, and take the car out for a test run. I'd be willing to bet it doesn't creep.

Also: If it really was boost creep, then it would be worse in the higher gears.

Can you post up a diagram of how your homemade boost control system is set up? It sounds to me like the ECU is still opening and closing the BCS (perhaps) and that is messing your boost up....

The thing with problems with this is, you have to isolate one variable at a time, to find the problem.

 

[tsigeoff]

my boost controller is a grainger valve. here is the site that describes how to hook it up and make a dual stage. Now this has always been on the car and I never had a problem with it.

http://pages.cthome.net/gus/mike.html

I went over the diagram for a dual stage and everything is correct. check it out and let me know what you think.

thanks

 

[RipperXX]

Originally posted by candela
Your posts allways give me a nice laugh ripperXX:laugh:

I am COMPLETELY NEW TO the world of turbo's! over the past few days (been about 5 days since i made that post) I have actuly learned a good deal... although i must say i was half out of it that night so even i gota kinda laugh at myself..