GFB boost controller problems/ boost oscillation?

[nty1234]

Hi all, weather is starting to warm up over here. Decided to start finishing my tune and dialing in my Huron speed single kit for higher boost. Been having some serious issues with the gfb3 boost controller. It has nice and stable boost pressure when duty cycle is at 10% (minimum). However, as I start to up the duty cycle problems start to occur. I upped the spring pressure to a 5.5psi spring which at a base pressure holds around 5.2-5.7 nicely. When I start increasing the duty cycle it will either not make a big difference at all or will increase a little bit and then start oscillating pretty bad 2-2.5psi. No idea if this could be a bad wastegate, boost solenoid, or even controller? I read another post on here explaining to hook it up a different way which goes against their instructions so I tried it and had no boost control at all. Just spooled up very quickly until hitting my boost cut-off in the tune. I know the general rule is 2x spring rate but I wouldn't expect to be having these problems way below that? I have messed with the sensitivity settings too to no avail. Tune is in Speed density only with maf disabled, a little on the rich side but it's a tad bit difficult to dial in when my boost is all over the place. I have tried attaching a few logs and even a screenshot but it will not let me upload anything. I will keep trying and update it. Thanks to anyone who can point me in the right direction.

[nty1234]

Well I guess you can't upload hptuner logs here. Anyways, here is a screenshot from one of them.

[Warship2k15]

Ok maybe I’m out of the loop on technology.But when tuning my grand national it was to put in a spring the equivalent of the lowest boost you where going to run and the boost controller would control it to a higher boost setting the the watergate spring.
So in effect if you wanted to go as low as 2.5 you should have a 2.5 pound spring in the wastegate.
If you wanted a lowest when on boost of 5.5 then you would use a 5.5 spring and be able to effectively control boost from 5.5 up.
And that would also explain the change in spring pressure causing the oscillation.

[Warship2k15]

Ok maybe I’m misunderstanding.Are you commanding 2.5 with the boost controller or are you getting the oscillation when passing thru 2.5 with the boost set higher.??

[nty1234]

Originally Posted by Warship2k15

Ok maybe I’m misunderstanding.Are you commanding 2.5 with the boost controller or are you getting the oscillation when passing thru 2.5 with the boost set higher.??

I'm using a base spring pressure of 5.5 (5.0 in that snippet above) and trying to command pressure above that, preferably up to around 9-10psi. I'd understand if it was going unstable at double the spring rate or more considering its not a c02 controller but going unstable a pound or 2 higher makes me think there are underlying problems. With the boost controller effectively turned off it holds base spring pressure extremely well. It's when you're trying to ramp the boost above the base rate that starts going unstable and oscillating. I have a video of it too I can post tomorrow if that will help. Turbo basically sounds like it has a very slow rev limiter of its own lol.

[mrimpala02]

What is your Duty Cycle set on? How about your Gain settings? I guess it would be helpful to list all the settings you have tried. I leave sensitivity at 0. Outside of duty cycle I saw the similar fluctuations by have the gain set incorrectly.

[nty1234]

Originally Posted by mrimpala02

What is your Duty Cycle set on? How about your Gain settings? I guess it would be helpful to list all the settings you have tried. I leave sensitivity at 0. Outside of duty cycle I saw the similar fluctuations by have the gain set incorrectly.

Well I was going back through all my settings to start fresh and realized I had the overboost feature set at 5.4psi

Set it to 7.7psi even though my hard boost cut in the tune is 7.2 and would you know it's fixed haha. Sorry to waste everyone's time and I truly appreciate those who gave me their input! I guess this is what happens when you install something in the winter and forget about it until the spring when it's time to finish tuning.

[Big Biscuits]

Love it when it’s a simple fix. Crank it up to 15 and hang on!

[nty1234]

Originally Posted by Big Biscuits

Love it when it’s a simple fix. Crank it up to 15 and hang on!

Haha me too. 15 may be a little far fetched for the stock internals but there is only one way to find out!

[mrimpala02]

Originally Posted by nty1234

Haha me too. 15 may be a little far fetched for the stock internals but there is only one way to find out!

Good deal! Glad you got it figured out. You will survive at 15 psi for while if you not dragging racing everyday. Mine has survived a while 12-15 psi.