Surging??

[phantom3]

Hey guys, I kinda new to this so bare with me.

I have installed a Greddy profec b spec 2 EBC in my car. (everything connected correctly).
I have the low setting set at 14psi and the hi setting set at 17psi.
The gain (boost deviation) is set at 7% in lo and 5% in high.
Start boost (pressure to open WG) is set at zero for both.
Lo runs fine with 1.5psi fall off by 6,000rpm (regardless of gain setting), But when ever i do a 5th gear pull in Hi I get a little studder at 5,600RPM every time.
Now i have the gain and set gain so low as to rule out surging caused by them.
In 6th it occurs more often starting around 4000rpm.
Peak boost in Hi is 17psi.
No matter what i set the gain and set gain to i always get a studder and major boost fall off (17 down to 13psi by 6000rpm).
WTF is going on?? is this boost cut? I thought that didn't happen until 18psi.
Is the K04 just not capable of flowing enough on the higher end?
Do i need a map clamp?

Any help is greatly appreciated.

[phantom3]

Bump... nothing?

[danems6]

you answered yourself... get a map clamp or boost cut defender..
if you have any sources of data logging (dashawk or similar), look to see if your fuel pump is keeping up...
im sure others could give you better advice but no one was yet so i thought i would give it shot.

[Jarods7920]

I have the same problem with myn. It seems to be related to fuel pressure. Least that is what i have found with data logs. on 15psi it is perfect accept for today it had a little hicup in third but its really cold here today. If i try and run 18psi the car stutters. Maybe we can compare notes and see what we come up with. All greddy says is to send it in and they will test it. I do have a clamp as well and the clamp doesnt do anything for it. I am going to add an AP this weekend and test with the AP installed.

[kingpin748]

If you got something to datalog with that would help.

I have the AEM Tru Boost. I was having a weird surging effect because I had the pressure to open the waste gate set to high. I see yours are set to zero.

Surging under throttle.

[phantom3]

I've been looking at getting the auto engunity for my laptop and using that but i'm so broke i can't afford to pay attention right now!

[phantom3]

Originally Posted by kingpin748 If you got something to datalog with that would help. I have the AEM Tru Boost. I was having a weird surging effect because I had the pressure to open the waste gate set to high. I see yours are set to zero. Surging under throttle.

Weird.... mine only comes under WOT....

[kingpin748]

Originally Posted by phantom3 Weird.... mine only comes under WOT....

What your describing is more like fuel cut or boost cut. If it's violent then you probably need a MAP clamp. If it's not then I would go with CDFP internals if you can find them.

Either way you should get something that datalogs in your quest to detonate your motor.

[Jarods7920]

I have logged it several times...and every time i come up with fuel pressure. I put a a 103 map on the car and i am going to run the car with that and see what happens with the fuel pressure. I remember reading somewhere that because it demands so much fuel because of the stock pig rich tune that that is part of the reason for the pressure drop.

here is my log