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Boost Creep - Overboost Problem - Any Ideas...

SevenAngryPenguins
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SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
Posted

Hi all i seem to have a boost creep problem after installing a high flowing exhaust system (jjr split dump, 3inch catco and power extreme II cat back), it boosts up to about 14 psi as the revs rise up (I even manually tied the flap all the way open). After doing a search it seems maybe the turbo cant flow enough through the wastegate housing or dump pipe any ideas? Will a bellmouthdump pipe help me? can i dremel out the wastegate housing a bit maybe?

My car is a s1 r33 with r34 intercooler and pod that is the limit of mods. Any help or ides welcome.

cheers.

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
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added brand new hks actuator today but, its overboosing when the gate is manually tied totally open the absolute min boost is 14+ psi problem seemed to start after installing high flow cat. Ill try dropping the exhaust tomorrow, going to try friends bellmouth too. The exhaust is brand new and the car makes very good power with it way more than the stock system. Is it hard to increase the wastegate size can it be done just using a dremel? If i can get it down to 10 psi i will be happy. thanks for the replys

Cubes Grand Master

Cubes

Posted
Posted

Its definitely not 'normal' for a stock turbo to boost creep.

My first point of call would be the dump pipe. The dump is what directly has an affect on the boost control in a closed system.

Maybe its just a bad one; possibly the point of merge for the wastegate split is a tad messy (not well matched) inside that restricts wastegate flow.

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
Posted

maybe I should dremel the dump pipe out a bit first then (the fitting was average with respect to the lining up of the flange bolts and the lining up of the waste gate pipe to the flange hole, I didn't think it would of had a huge effect at the time, soon see though) Im not really keen on taking to the turbo with the dremel. I just want to dremel something now!!

MANWHORE Grand Master

MANWHORE

Posted
Posted

It is not an exhaust freeness problem.

You either have a problem with vac hose plumbing or with your actuator.

There is absolutely no need to dremel out anything.

I've never had any problems, even using highflowed turbos pumping out 20+ psi. Standard size hole is fine.

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
Posted

Ok I definitely wont dremel the turbo then. The pipe and actuator are brand new as that is what i thought the problem was too but still overboosted so i disconnected the actuator arm from the wastegate flap and put a zip tie on the flap so that it was all the way open to me this says that i should make very little boost but when I took it for a drive it still had no problem boosting to 13 psi but not till high up in the revrange. Thanks for all the input.

Cubes Grand Master

Cubes

Posted
Posted
It is not an exhaust freeness problem.

You either have a problem with vac hose plumbing or with your actuator.

There is absolutely no need to dremel out anything.

I've never had any problems, even using highflowed turbos pumping out 20+ psi. Standard size hole is fine.

Its deifnitely not a vac hose/actuator problem. As per his first post he has tied the wastegate wide open and it still boost creeps.

I would definitely be looking at the wastegate dump to turbine dump merge point.

Pic attached.

post-382-1185580689_thumb.jpg

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
Posted (edited)

Ok the dump is off, too me it looks like the wastegate is exiting straight onto the flange maybe (the blackened part) oh and the best part a bolt snapped of in the turbo and my o2 sensor is stuck in the pipe.

cheers

post-36364-1185581700_thumb.jpg

Edited by SevenAngryPenguins
Cubes Grand Master

Cubes

Posted
Posted

Another thing to check.

With the dump on does the wastegate foul with the dump when attempting to open it fully? Possibly the dump is preventing the flap from opening fully? Unlikely but worth checking while its all off.

Compare the opening angle to that of the std dump if you still have it.

I always throw some antisieze on the thread of the o2 sensor. Supercheap have little satchels for around $1 each.

cosworth1971 Community Regular

cosworth1971

Posted
Posted

mine is same 13psi what ever i do ,it wont boost lower :P .my dump is a single track but big size.autos are 5psi standard but manuals are 7.2 standard boost without intercooler /exhaust.

ive tried alot of thing but to no luck yet

mad082 Grand Master

mad082

Posted
Posted

the 2 things i would look at are:

1, when the wastegate is open is the air still able to flow past it. the wastegate may be opening without fouling, but it may be blocking the path of the air through the wastegate pipe of the dump pipe.

2, chech where the wastegate pipe blends back into the dump pipe. the one i had the pipe was welded off to the side of the hole. it didn't leak but when you looked at it from the inside half of the hole was covered. so i got the die grinder out and opened the hole up. i had to take a section out about 4cm x 0.7cm.

T04GTR Grand Master

T04GTR

Posted
Posted
Drop the exhaust, just before the cat, and see if the creep goes away.

If the creep goes, something in the exhaust maybe restricting flow. Check also for any air leaks to the actuator.

itrs the other way around dude.

your wastegate isnt flowing enough. perhaps try putting the standard dump pipe back on. that will solve it.

MANWHORE Grand Master

MANWHORE

Posted
Posted
Its deifnitely not a vac hose/actuator problem. As per his first post he has tied the wastegate wide open and it still boost creeps.

I would definitely be looking at the wastegate dump to turbine dump merge point.

Pic attached.

Oops, silly me. I didn't read the first post carefully. Just thoguht it was the usual wrong plumbing/faulty actuator

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
Posted (edited)

ok this is what im thinking that the wastegate flap was fouling just a little as it feels different to move now than when i did when the dump pipe was on. I don't have the old dump to compare too but when i place the dump pipe gasket over the pipe the top hole (waste hole) doesn't look like its even close to lining up with the turbo waste gate. I'm not sure I think i will just buy a bellmouth dump pipe and see how it goes after i pull the turbo off to get that damn bolt out!! Maybe should highflow it while its off hmmm......

post-36364-1185602642_thumb.jpg

Edited by SevenAngryPenguins
skylinecouple Experienced

skylinecouple

Posted
Posted

Hi Chris,

The waste gate is fouling on the bracket that holds the turbo heat shield or it is hitting the side of the flange.I had this very same problem but due to work commitments had no time to really look at it for a year.When I did look I found the original dump flange was a lot thicker than the stainless with separate waste gate.So the waste gate arm was hitting the bracket holding the heat shield stopping it from opening more than half way.I could wind the boost up to 14lbs but any more and boost would go crazy fluttering up and down.Bear in mind my turbo was high flowed and would operate better with a bigger exhaust wheel but with a standard turbo and hence smaller turbine wheel you would get the same thing happening at a lower boost setting.You only have to take the cover off and take off the circlip with a fine screw driver then pull the actuator rod to take some pressure off the lever and lift it off.Now that the wastegate arm is free to move it should be able to swing around to face directly over the dump pipe at a right angle to the flange.If not,well,there is your problem.

SevenAngryPenguins Proficient

SevenAngryPenguins

Posted
  • Author
Posted (edited)

yeah my arm hits on the heat shield and then it seemed to drop down into a slot and to move it back it had to be lifted up (has bit of up and down movement) this is stock setup though..... how far does the actuator need to travel? my flap operates correctly with the pipe removed not sure about when its on ill check when the turbo is off, should i modify my heat shield did this solve your problem?

Edited by SevenAngryPenguins
RBWPN.6 Collaborator

RBWPN.6

Posted
Posted

Hey i got similar issues i think i got an xforce turbo back 3inch with hi-flow cat and FMIC and airfilter no boost controller gettin a reading of 12psi and car seems to not wanna rev past 5000rpm...nethoughts?

skylinecouple Experienced

skylinecouple

Posted
Posted

Because the flange is thinner the bracket is closer so just put 2-3 thin washers in between the flange and bracket to space it out a bit. Only has to be the difference between the old flange and new,so only a couple of mil.

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