Wastegate Opening To Early

[ppctx]

When you leak checked your IC pipe, did that test include the mani all the way to the valves with the throttle plate open?

What are your AF on boost\vac and how is your valve cover and PCV plumbed?

I think sourcing from the same location like WD said will tell you something but that would be one hell of a head loss if that cures it, if it does $10 you got a rag stuck on the hot side of the IC.

[C-Kwik]

Your vaccum source for your wastegate should be comign form your intake mani. I use it from my FPR line 0 problems

I know this is an old post, but I missed it the first time around.

The boost signal can be sourced anywhere between the compressor and the engine. It changes the characteristics slightly but ultimately, it will have a similar result.

The closer to the compressor you mount it, the more responsive the WG will be to boost (at the manifold). A signal sourced from the manifold will result in a slightly delayed response from the compressor as the compressor will have already started increasing boost beyond the set boost by the time the wastegate sees the manifold pressure has reached the set boost level. That means you will experience a slight spike (typically unnoticable) as boost hits the set level and then level out. A signal at the manifold will also be more accurate as it will account for any pressure drop.

That said, for this particular problem, assuming the spring is truly the right one, then I would speculate there is a boost leak. Since you are sourcing from just behind the compressor, any boost leaks would not be accounted for by the compressor.

Try hooking up the boost signal to the manifold. You can simply run a Tee off the same line for your boost gauge. If the boost increases to the spring's rating, you h ave a boost leak. If not, then remove the wastegate and usig a pressure pump, supply a known amount of pressure. It should open at just about the spring's boost rating. If not, the spring is not applying the correct pressure. In this case, you can try and obtain the correct spring, or simply use a boost controller.

If you do have a boost leak, fix it. Band-aiding it by using a boost controller or sourcing from the manifold will cause your turbo to be working harder than it needs to and it will operate in a different area of the compressor map than you might intend.

[turbo2nr]

hmm very good point i will have to try tee- off form my vac block now. well after work im going to a shop to test for vac leaks again, if that doesnt work then ill try the boost signal form the manifold instead of the turbo.

i still think its a leak because under full accereration when the wastegate is open boost pressure still drops.

[spooled240]

disconnect the wg and try to boost over 4 psi, but be careful.

[nelson8708]

^ he already tried that and it went to 14psi before he let off.

I am in the same boat. I have been running 2 psi through two different setups. Everything has changed and still 2psi. I have gone through:

2 engines (no i didnt blow one up...just decided to rebuild another)2 intercoolers (smic and now fmic)2 bov (greddy type s and a 1g)2 turbos (sr t25 and Holset H1C)2 wastegates (sr t25 internal and 38mm tial knock off)3 different vac sources (Compressor housing, Vac line off intake manifold, and Tee'd into the brake booster line)

The car runs fine but, it just runs low boost. How ever if i put a mbc in line to the wastegate it will run wastegate pressure. On the t25 when i had a mbc in there and had it turned to zero it ran 7psi and now with the new setup i am getting ready to put the mbc on it and i am pretty sure it will run the 6psi it is supposed to. I never figured out the problem....but, i did find a solution. Watching to see if you find the problem so i can follow suit and fix mine also.

GL

[spooled240]

^ try an exorcism..you car has a weird *** problem.

[Specvengeance]

Was this ever figured out?

I am having a similar problem,except I am running an open Wastegate dump, and as soon as I start the car up the wastegate cracks open.

Any ideas?

[WDRacing]

What type of wastegate?

[spooled240]

you know what happened to my tial one time when i was doing a time attack was the small allen screws that held the valve shaft onto the diaphram came loose and the valve was wide open.

the spool was super slow/nonexistent lol. I could only build a few pounds of boost at 5000 then it would get up to about 6-7 at redline..something was not right. My times immediately began to suck and vdubs were on my a** something was definitely NOT RIGHT.

[nelson8708]

i was running 7psi the whole time when i was having the problem (gauge reading 2psi). I removed the fmu which was on the same vac line as my boost gauge when i went to a tuned ecu and the problem was gone.

-Nelson