Boost Creep?

[theKnifeArtist]

so this is the situation.
i'm currently running stock boost. no manual boost controller.
the wastegate opens at 5psi and it'll climb to 10psi.
i got a ddp.
i thought the wg was supposed to stay closed until set pressure, no?

what goes on here?

 

[Sawbladz]

Sounds like you need to enlarge the wategate opening. This usually helps eliminate the boost creep.

 

[theKnifeArtist]

you mean open up the wastegate and bore out the hole with a dremel?

so does that mean that the stock boost is 5 psi?

 

[swaq]

Stock boost is 6.8 psi, if I recall correctly.

 

[Dunckel]

Boost for an A340E is a little lower, IIRC it is around 4.0-5.5 psi.

EDIT: 4.8-6.0 psi. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=TC&P=5

 

[starscream5000]

What you are describing has happened to a few others that have a DDP. Not all people have this problem with a DDP, but a few do.

 

[7MGTEsup]

I have this same problem yet I don't even have a DDP. Actuator set to 7psi holds 7psi till 4000rpm then just shoots up to 13psi by redline with no boost controller. Mods are home made 3" exhaust from elbow back, modified stock elbow and a K&N drop in filter.

 

[theKnifeArtist]

hmm, so all i can do is bore out the wastegate hole..
dammit, i wish i woulda known before..

 

[Syris]

you can get an ebc to eliminate it

 

[theKnifeArtist]

ahh, yes i didn't think about that. but man, what's the cheapest one like 300 bucks?

 

[Syris]

Yea I think you can pick up a greddy for around 300

 

[jtran8]

EBC only iliminate boost spike , it won't help your boost creep . 9psi -12psi of boost is normal for 3" turbo back+cold air intake.Threre onlytwo reasonsthat you have boost creep #1 if the hose between turbo and wastegate accuator wore out and leaks #2 if your set up so efficient that cause more air than waste can open . So if the your waste gate accuator hose still in good condition , than you have to port your wastegate to iliminate boost creep if you want to run under 10psi of boost.

 

[theKnifeArtist]

well, i wanted to run it at like 12-13psi, but i have yet to put the boost controller in because i don't want it to creep up after i set it higher. am i thinking clearly? or if i set it higher, would it stay at the correct level?
and my vacuum line is good, its a nice flexible hosetechniques line

 

[jtran8]

as your fist post, you said boost creep to 10psi , is that on 3rd gear at 6000 rpm ? if so then you are in good shape and yes you can install boost controller and turn up the boost to 13psi , if your head gasket is fixed or at list retorques it. I thought you only want to run under 10psi .

 

[IJ.]

you can get an ebc to eliminate it

Ummm nope if it's got creep it's a mechanical issue and no EBC will correct it....

Creep is usually not enough flow from the WG Valve to control/reduce Turbine speed at high rpm due to the volume of gas flow the engine produces.

In the CT the WG Hole is very restrictive along with the stock elbow but in this case he has a DDP.

If you have any shims remove them as preloading the actuator reduces it's travel when opening. (there might be just enough travel in a stock actuator to control it unshimmed)

Add an EBC to control the actuator will improve low end response as it holds the WG shut until your boost setting, plumbed stock the WG begins to open as soon as boost goes + and this slows spool.

 

[Syris]

good to know thanks for clearing up guys

 

[theKnifeArtist]

i don't have any shims, and i can't tell you exactly at what gear and what rpm what my boost sits at because it's automatic and hard to tell what gear im in when boosting..this erratic auto doesn't really help.
according to my headgasket setup...oem hg+arp's@85ft.lbs, i should be safe up to fuel cut.

 

[daddycat31]

how many washer are supposed to be on the waste gate? mine wasshimmed when i bought it. i am having a similar issue, but i have a mbc. for the most part it stays right 10psi, but sometimes when i punch it, it will shoot upo to like 16psi and i hit fuel cut.

 

[IJ.]

None....