SilverEK96

iTrader: (11)

WHERE THERE WAS NONE BEFORE!!! Ok guys, need some help/advise. Last year I was on a stock sleeve piston and rod block. I purchased a new turbo and went and got tuned. I cracked a sleeve and went ahead and got a new sleeved 84mm block. That is the only thing I changed out from my previous setup. I went to get tuned just last week, but I had major boost creep issues! I have a Tial MVR 44 gate with a 8 psi spring in it. The boost was going up all the way to 16 psi. We disconnected the boost solenoid and ran it straight from from the Wastegate (bottom port). At this point it was still creeping all the way to 16 psi and climbing. We knew somthing was definitely wrong as boost should stay at what the spring rate is or at least close to it. So now I have no clue on what it can be as I never had this issue before!!!

Setup:
BWR Ramhorn Manifold
4 bolt downipe and 3" exhaust
Predator Turbo
Tial 44 MVR


Things I've done ...

Checked for leaks (couplers, pre turbo and exhaust leak) NONE

Vacuum leaks ( car idles perfect and gauge needle does not move) NONE

Turbo ( all blades are in perfect condition, turbo is also fairly new, >600 miles )

Wastegate - Diaphragm was slightly pinched, no tears at all. Guess I did this when I changed springs out when I first bought the wastegate. Still at that point never had boost creep issues till now.

To me all signs are pointing towards the wastegate. Now the question would be, can a wastegate go bad ???

Anything else it could possibly be or that I can check???

joe b

To test the waste gate , i would simply use compressed air on the bottom port . You would need to regulate the pressure though . So assuming you you have the 8 psi spring run 8 psi of pressure to it . It should open , if not then up the pressure until it does. You have to closely watch the air pressure so you can verify proper operation .

SilverEK96

iTrader: (11)

Right now I have the green/blue spring in it, 8.70 psi according to the spring chart. Once I do this and let say it doesnt open up till like 14, 15, psi etc... Does that mean the wastegate is shot?? Also does anybody know if Tial rebuilds there wastegates for customers ??

LTCxD2B

You should also test the spring ....by itself and test the waste-gate operation without a spring in it like the if the valve moves freely

Turbo-LS

iTrader: (4)

Picture of wastegate outlet on the manifold

SilverEK96

iTrader: (11)

When we opened up the wastegate to check the diaphragm the valve did have some play in it. Not sure how much it suppose to move, but when i shook it side to side it would move around a bit. Is it not suppose to have any play in it ?

This one isnt mine, but I have the exact same manifold and outlet is the same.

boostjunkie757

full-race knock-off.



ive got a similar knock-off manifold myself.

LTCxD2B

Did u test the spring ? Does it open consistently at 14-16 or is it random?

KevinEF7

The manifold isnt the problem as you know. I would at very least remove and blow air through the vacuum lines you are running to the gate, ensure there is no debris clog (ive seen a spider nest inside 4mm lines) , or if they are weak/soft they could be collapsing.

On another note, why tune for 8psi on a sleeved block?

DraginX

Did you retune the car? What are your afr's at?

met

Also cam timing/phasing is something to consider. New block more than likely different deck height can effect the cams position. I went through the same thing, no boost creep, then took the head off fresh rebuild. After a light deck then I had boost creep. Once on the dyno we dialed the cams in and all the creep went away. I was pretty shocked, I did a lot of reading after all this. Cam phasing was an aspect I never really considered. Its something to turn to once you know all the above is checked.

SilverEK96

iTrader: (11)

Haha.. its a knock - off of a knock - off

I honestly dont have a way to test the spring or the know how. If you care to explain how to test it I will do it or find a way how to.

I've actually replaced all hoses with brand new ones and made sure all wastegate ports are clean free of debris. Also the 8psi was just a base to start off. Boost by gear would of taken care of the rest as I had it set up before . Think I used to have 8psi, 12psi, full boost , full boost ...

Yes the car has been retuned. If your talking about the AFR's under boost they are sitting close to 12 under load.


I have drop in cams, I'm running skunk2 tuner 1's on stock cam gears. So I really dont have a way to degree them. Dont know if I can rule it out though .

SilverEK96

iTrader: (11)

Also to add from the last time, I did try some new things out ..

Changed the boost signal from from compressor housing to vacuum box - Car is till boost creeping

As stated above , replaved all vacuum hoses with brand new ones

Now with that not improving anything, I will be changing out wastegate springs to stiffer ones. Going with 10.15 psi springs, there brand new still in the box and that will rule out if the old springs are bad . I'm also replacing my diaphragm. The current one was pinched before, but not torn. Read in a few other forums people had boost creep when there diaphragms were pinched, so it wont hurt to replace it.

I really want to try out another wastegate, just to see if that is the problem once and for all. But nobody that I know of has one . Somebody let me borrow theres lol .. I'm an honest guy, I'll return it right back :p

yessewey

iTrader: (2)

You get it figured out yet??

SovXietday

Take the spring out of the wastegate, and run the car like that. Your car should make no boost at all.

If it does, the manifold is your problem.

If it does not, then you have a vacuum leak/wastegate diaphram/boost controller issue.

The fact that you checked the couplers for boost leaks tells me you are not thinking the problem through at all.

SilverEK96

iTrader: (11)

I actually did this earlier today. I ran the car with no wastegate and it did make some boost. It went up to like 3 psi max. With that being said , is the manifold absolutely not suppose to make any boost ? Is there such thing as acceptable amount ? What I don't get is how the same manifold and wastegate combo is now giving me problems. Prior to me buying this turbo , I ran a 6262 with same manifold and wastegate . Held boost perfect !

As for the couplers , I was just looking for tears. Had read on another forum that if car is leaking boost through a small tear that it could make the turbo work harder. That could also cause boost creep. Tomorrow I will be checking timing and making sure timing belt didn't jump a tooth and also same wastegate with a brand new diaphragm and 4 psi spring. Also removed top port to vent to atmosphere. Thanks for all the advise and keep it coming before I drive this car off a cliff !

SovXietday

I'm not familiar with the predator turbo. Did you change the hot side sizing at all as well?

If you stepped up in hot side size, that could easily be accounting for your issues.

A poorly made exhaust manifold will rely heavily on back pressure at the turbine housing to regulate boost. With smaller housings, or housing that do not flow as well, the exhaust builds up pressure and when the wastegate opens it is much more inclined to go to the low pressure area than try to go through the turbine. Therefore you get a very effective wastegate setup.

When you have a very efficient exhaust housing you don't get that pressure build up, and the manifold therefore relies considerably more on wastegate priority in the flow. Without the manifold directing some flow to the wastegate, it will simply never be able to be effective enough to work properly.

At this point I would check your entire system as a whole. Do a full boost leak test and make sure that at 4psi your wastegate is opening properly. Once you have confirmed that everything is the way it should, try it again. If the problem persist, you will need to have the wastegate inlet modified to either have better flow or to step up in size.