Quick (and probably easy) boost question

[knochgoon24]

My car doesn't like WOT. It doesn't even like 75% throttle. When I hit the gas hard, the turbo spools up nice and quick (still have the T-25) all the way up to 15psi (sometimes spiking to 17, not sure about that either). After it hits 15, it then starts to wobble between 12 and 15psi. You can really feel this. This only happens if I'm hard on the throttle. There's a big hill near where I live, and if I hit the gas slowly, I can actually get it to boost a constant 15psi up it.

I have checked for boost leaks, it holds 20psi fine.
I run 93.
Pulled the spark plugs last week. Tips looked clean and carbon free.

I do have an ebay greddy type s BOV. I cracked the stock 2g one, and figured that I'd try the bike tire trick if it ever craps out on me. It's only temporary.

I'm still running the stock BCS. This is one reason why I'm confused. I haven't removed the restrictor, but I'm still able to hit 15psi and hold it. WTF

I've spent several trips dialing the BOV in so that it opens with a woosh after letting off a heavy throttle. It does have that turkey call stutter under low boost.

Car is an auto.

I have a simple ELM logger. I can try to log a pull later. Tell me what you want. I don't have a wideband yet because I really don't have any mods. Those happen this summer.

Any ideas?

 

[cruisintalonawd]

I would say its you wastegate maybe something else, what you have it boost spike though

 

[knochgoon24]

I'm going to try and bypass the BCS and run the wastegate directly off the boost source. It will only run 8-10psi, but I'll see if that helps.

Ok, since it was nice today, I took my logger with me when I went out and had some fun. I did bypass the BCS and that kinda helps. For some reason, I'm still wavering between, just now it's 8 and 10 psi. It's not as bad or as noticeable as it was between 12-15 but it is still there. Shouldn't it hold solid?

EDIT 2: Forget that I even took my logger. The only WOT I did was from a rolling start. It took 4 sec to go from 30-85mph (3k-6.2k) and those wonderful OBD-II loggers don't give a good enough resolution, since they are reading once a second. (Polling 5 things)

I still have that "boost wobble" problem for you guys to talk about still.

Sorry to triple post, but might I have to do some porting already?
http://www.dsmtuners.com/forums/problem-diagnosis/174287-help-boost-surge-w-mods-t-25-hitting-20-boost-now.html

I've never heard of anyone having to port with a T-25. All I added was a BOV.

It explains the hard surging at 12-15psi, but not the 8-10psi stuff. I ran 12psi all day stock.

 

[silver bullit]

The turkey call stutter is compressor surge your bov is not letting of at the lower boost pressures good way to kill your turbo.

You have nothing done to your car, you should not be boosting more than 15. Sounds like your hitting fuel cut.

 

[lazyazzdaddy]

have you checked for boost leaks? or checked the waist gate shaft on you t-25? could be sticking.I've heard of countless people haveing that problem.. if you do a search there are instructions for how to check/fix that problem

 

[cruisintalonawd]

have you checked for boost leaks? or checked the waist gate shaft on you t-25? could be sticking.I've heard of countless people haveing that problem.. if you do a search there are instructions for how to check/fix that problem

READ

 

[lazyazzdaddy]

ya sorry i did'nt catch that the first time thru

 

[knochgoon24]

I don't think it's fuel cut. It's not a brick wall feeling. It just wobbles between the 12-15psi. I also noticed that it still wobbles even though I have the wastegate connected directly to the nipple on the turbo. I'm only gettin 8-10psi and it still wobbles between those. I can try to check the wastegate arm.

As for the turkey call sound, should I just back out the adjustment screw some more, or does it need tighter?

 

[cruisintalonawd]

loosen that screw