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Discussion Starter · #1 ·
Hey guys- I have done some research but I'm a bit confused where to start to figure out why my SE is going into an over boost scenario when I accelerate hard. It basically pins the boost gauge to the right and then cuts power for a second or two- I'm assuming to protect the engine.

Is it more likely to be a fuel issue? Wastegate? Or I was leaning towards the boost control frequency valve.

I will note that recently I had my injectors and ECU changed so the fuel rail was out while testing that everything was working correctly.

Any suggestions?
 

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Cal H
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Hey guys- I have done some research but I'm a bit confused where to start to figure out why my SE is going into an over boost scenario when I accelerate hard. It basically pins the boost gauge to the right and then cuts power for a second or two- I'm assuming to protect the engine.

Is it more likely to be a fuel issue? Wastegate? Or I was leaning towards the boost control frequency valve.

I will note that recently I had my injectors and ECU changed so the fuel rail was out while testing that everything was working correctly.

Any suggestions?
Look at the wastegate capsule. A lot of times the vac hose to capsule will fall off or come loose/leak. That will give the exact symptoms you describe. I was driving one day and my boost pegged all the way to the right, I think the fuel pumps are restricted to protect the engine and it felt like it was running out of gas until the turbo boost level drops into the safe range restoring power .

There is a chance that the membrane in the capsule is bad but that is rare unless you were fiddling with the control rod and rotated the rod instead of the adjustment nut tearing the attachment point. So don't touch the waste gate actuator rod unless you are familiar with it.

Check the hose along the entire length for splits or leaks. Also the hose is connected to vac solenoid in the front wall of the trunk just rear of the coolant header tank. If that fails it can also give you that symptom.

Good luck and tell us if that was it.
 

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If the frequency valve is not working or is disconnected you will not get overboost, unless it is broken in a stuck open position. You could test that by disconnecting the two hoses from the turbo and wastegate and then blow air through one of them into the valve -- it should not allow air to pass.
 

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definitely look into the hoses between the boost control frequency valve and turbo as mention above.

But if those are fine.

Are you getting over boost consistently? Or is it boosting once, backfiring, and then boost is restricted to ~.65bar for a few minutes? If so then it is possibly the ECU cutting boost due to a lean condition. I had that symptom after changing the ECU Memcal Chip and with new injectors, turned out my fuel pump was not supplying enough pressure to cope with demand under boost.
 

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Discussion Starter · #5 ·
Wow- thank you! I did find a split in the hose from the wastegate. No more whistle and she seems to be boosting normally. I would of been searching for days to see that without guidance. I really appreciate the help.

You guys are awesome
 
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