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G4+ fury closed loop boost control boost spike


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Hi All,

I have a G4+ fury ECU with closed loop boost control setup by my tuner and I'm having a few issues with the boost spiking a bit. 
Every now and again the boost will spike well past the target, causing the overboost fuel cut. Doesn't happen all the time (in fact it hadn't happened for about the last 4 months, but has started happening agin), but does seem to happen a bit more when the car has a bit more weight in it.

Does anyone have any advice as to which settings I should alter to prevent this? I've attached a couple of screenshots below of the boost control settings at the moment. 
I haven't really played around much with closed loop before, so I'm not really sure what the best place is to start to be honest.
I don't mind if it spikes a bit coming on, but this is excessive haha. 


1jz vvti
GTX3076, 0.82 rear
turbosmart 50mm external gate.
Peak boost target: 234kPa
MAP fuel cut: 270kPa

http://i213.photobucket.com/albums/cc145/jposupra/log screenshots/aux output boost.jpg

http://i213.photobucket.com/albums/cc145/jposupra/log screenshots/boost setup.jpg

http://i213.photobucket.com/albums/cc145/jposupra/log screenshots/boost PID setup.jpg

http://i213.photobucket.com/albums/cc145/jposupra/log screenshots/boost target table.jpg 

http://i213.photobucket.com/albums/cc145/jposupra/log screenshots/wastegate duty cycle table.jpg

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If you have a look at the help file, perhaps your Stage 2 kPA is too low. This would potentially lead to overshoot.

I'm no expert but I wouldn't expect the wastegate DC table to look like that, particularly not with the boost target shown (ie, it is relying too heavily on closed loop rather than the underlying DC table), although it may not make much difference in practice.

Also the most commonly used MAC boost solenoid is supposed to work better with 20hz or less. You may of course have a different one and 35hz is fine.

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CamB is right when he says that the closed loop boost control system should not be relying too heavily on making changes from the values in the wastegate DC% table. It may be worth saving your base-map to your hard drive, and then turning the boost control system to open loop and see how the performance of the system is.


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I've found when the wastegate boost source is located at the turbo outlet there can be spiking issues when trying to hold the wastegate closed until closer to the target, I moved the pressure source to just before the throttle body and this sorted the problem and made it easier to tune the wastegate numbers.

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had a play around on the weekend.

Adjusted the stage 2 on value to 40kpa
I couldn't see the MAC number on the boost solenoid without pulling it out so I couldn't confirm preferred frequency - I lowered it to 20hz anyway, as it is likely a common solenoid.
Then I adjusted the duty cycle table whilst test driving.

I need to do some more testing and logging, but I'm pretty happy with it so far, boost looks really stable.
From here I think I'll pop it into open loop and check/fine tune the duty cycle table, then I may have a play around with trying bring it on a bit harder/earlier


thanks for all the responses, the help is much appreciated!


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