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Pain in my ass MS boost control

grnmachine02

grnmachine02

Indicating?
Joined
Jun 14, 2007
Location
Fredericksburg, Va
As you can guess by the title I'm having some issues with MS boost control. Long story short, I can't control boost worth a ****. Some gears it will go right to the target and stay there. Sometimes it will overshoot and then fall below and then surge up and down. I thought it was a solenoid problem so I got the latest and greatest solenoid from DIY. Then I thought it was a wastegate adjustment problem, but still no dice. I know the solenoid is working because I can change the duty cycle and it will react accordingly, however it just seems very inconsistent.

edit:// this is on MS1 and i'm using open loop boost control.
 
Yea that's always the complaint people have had. Everybody says the DIY one isn't that great so I bought a MAC valve. Haven't gotten it implemented yet though.
 
I'm using the AEM Mac valve, and control boost via Ms3, works flawlessly. Not sure if there are boost differences between the 2. I'm running open loop too.
 
I never got the target seeking closed loop mode to work very well. It would usually overshoot, then hunt back and forth. Probably some magical set of parameters would have made it work properly.

What I did was just use the open loop fixed DC tables. It's relatively easy to tune those, they seem to be rock solid once tuned (unless you change something). Boost build quickly to the limit, holds there solidly, lovely. You just have to hand tune the DC's to match your desired amount of boost, where the closed loop would (in theory) just let you enter what boost target you wanted.

PS: Maybe try different frequencies? Different hardware probably likes different frequencies. I was using a cheap GM Syclone valve. My new BW EFR has a built in (more bolt on, but whatevs) boost valve, I'll have to retune because of that and the different cams/turbo/exhaust.
 
I also found right around peak tq, I had to lower my duty cycle a little to not go over, then add it back with a gradual climb out the top to maintain boost. That was on E85, my gasoline table is stable then climbs gently to maintain boost.
 
OK so I did some trouble shooting on the way home. I got it to hit target boost, but then it would oscillate all over the place. I had the PWM set at 19.5, I cranked it down to 9.8 and I have rock solid boost. DIY claims that their solenoid only works between 19 and 40hz. Am I slowly killing my solenoid?

Douchenozzle: (lulz). I tried an nxs manual controller and it was giving me damn near 8 psi spikes so I took it off.
 
lulz indeed.

Wouldn't a lower frequency mean it's cycling it less? I'd imagine 200hz would burn it up, but less?

I'm usually bad at electronics though.
 
If it used to work, and now doesn't, something else has changed.
Make sure your wastegate arm is properly adjusted.

Also, don't run 2x (or more) wastegate pressure. If you want to do that, either shorten the rod more or get a stiffer wastegate.
 
grnmachine02 said:
Douchenozzle: (lulz). I tried an nxs manual controller and it was giving me damn near 8 psi spikes so I took it off.
Click to expand...

Aha. Then the issue has been found. If you can't get the MBC to work, the EBC won't either.

Where's your boost reference?

Like mafoose said, WG sounds like it may not be set properly.
 
doucheNozzle said:
Aha. Then the issue has been found. If you can't get the MBC to work, the EBC won't either.

Where's your boost reference?

Like mafoose said, WG sounds like it may not be set properly.
Click to expand...

See i thought that as well. I've both tightened and loosened the waste gate arm and it seemed to have no effect. By lowering the hz in MS I seem to have gotten it to work, but I feel like i've just put a band aid on it instead of fixing it.

My boost reference is right off the compressor housing.
 
I may have a solution. I have a holset actuator sitting around here. Should be high teens - maybe more. I bought it on ebay a while ago cheap because the adjustment rod was seized :roll: Some penetrating fluid and a day later it was fine.


You've given me enough stuff in the last year, it's yours if you want it.
 
MrBill said:
I may have a solution. I have a holset actuator sitting around here. Should be high teens - maybe more. I bought it on ebay a while ago cheap because the adjustment rod was seized :roll: Some penetrating fluid and a day later it was fine.


You've given me enough stuff in the last year, it's yours if you want it.
Click to expand...

I may take you up on that. After setting the hz of the solenoid way down, I seem to have achieved good results. But we'll see how long that lasts.



edit:// thanks for all the help so far everyone!
 
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