Need turbo help

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354
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Washington
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So im suddenly getting compressor surge. I installed a forge bypass valve with the weakest spring it came with. I did get one surge with its first opening after install then it went away. I also installed a adjustable wastegate actuator. My tuner said to start at 1 turn in. Did that and now i constantly get surge/stall when i shift it stalls the turbo and i can feel it fall on its face. I have to rebuild boost after shifts. It used to be insta spool but now its like a 1.5 sec lag. Also sometimes under 1.5 lbs of boost the bpv wont open and i can hear the blades chop the air. I also tried half a turn on the wastegate arm with no change. I havent tried no turns on the arm yet. But what do u guys think bad tune? Bad part? Also i didnt have the surge stall issue with just the bpv installed. Also no boost leaks. Everything is installed correctly.
 
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6,819
Location
California
Before blaming the tune, the turbo/wastegate/BOV need to be setup properly. I have little experience with this, but I know of a mechanic who also tunes and he wants to make sure the baseline is there before tweaking. Check for leaks on all the piping, the turbo is sized, and that the wastegate and BOV/BPV are in working shape.
 
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429
Location
California
I suspect the BPV could be failing to open when you let off the throttle. BPV relies on vacuum/pressure differential between charge pipe and manifold. Valve stays shut with a small differential while throttle is open; large differential when throttle is closed causes valve to bypass. Get a hand vacuum pump and test the valve by applying vacuum to the signal port to see if it moves properly. Wastegate actuator alone should not be causing those symptoms, but if you could revert to previous wastegate actuator setup that might help troubleshooting.
 
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6,136
Location
Illinois
Make sure the orings are good and it is lubed too. The Forge requires at least annual service. They have service kits for them for around $25 which includes the orings and a new piston plus some grease. I use the yellow spring and a shim and see 22 psi boost max. Valve Spring color coding: Green - 5-15 PSI Yellow - 15-23 PSI Blue - 23-30 PSI Red - 30 + PSI *The above figures are estimates only and should only be considered as a guideline*
 
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CT8

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15,408
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Idaho
Suddenly? You made serious modifications. I gave up on modifying anything I own 40 years ago.
 
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8,074
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New England
As has been recommended, I'd return individual items back to stock or stock-like and see where the fault lies. If you return fully to stock and the issues is not resolved, then it's likely the tune. // Some Questions: Why are you using a manually-adjustable waste gate actuator? Why can't your tuner simply adjust your waste-gate duty cycle tables in the tune itself? I'm only familiar with turbo Subies, and I'm not aware of these things ever being used - sounds janky. Why did you install a new BPV? Did you have issues with the stock valve leaking or does the new one just make more cool-sounding noise? Also, is your new valve really a bypass valve or does it vent some/all air to atmosphere.
 
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NE,Ohio
Quote
I put a new engine in my car and suddenly it acts different.
ok maybe it wasnt that much of a mod but that is a serious difference. if it worked before and doesnt now.. you need to either put the old back on or adjust it properly. Also is the tune designed for this type of BOV?
 
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6,136
Location
Illinois
Did the problem start immediately with the new BOV? Are you using a factory BOV solenoid or just intake vacuum to run the Forge?
 
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354
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Washington
Thread starter
Intake vacuum to the forge. My tune can do the receculcting or atmospheric bypass valve. Stock is recec and the forge is atmo. Yes the stock bpv wont hold past 18 pounds and leaks. Also the stock wastegate rod has corrison issues and has a weak spring too. Both r needed to run 20+ psi. I was over boosting with the stock parts leaking and it was commending more boost due to leaks. Im set for 22.5 psi. Overboost is set for 23 and will put it in limp mode.
 
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8,074
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New England
Originally Posted by Dylan1303
Intake vacuum to the forge. My tune can do the receculcting or atmospheric bypass valve. Stock is recec and the forge is atmo.
Stock is always recirc. It is called a bypass valve (BPV), because it recircs back to upstream of the turbo, so that no metered air is lost (doesn't mess with your MAF-measured amount of air being sucked/blown to the motor. Your Forge is a blow-off valve (BOV), because it does not recirc this metered air back to the intake. How does your tune account for both? That does not make any sense to me. If your tuner says it does and can't explain how to you in layman's terms, then he's full of it.
 
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Location
Washington
Thread starter
Originally Posted by gathermewool
Originally Posted by Dylan1303
Intake vacuum to the forge. My tune can do the receculcting or atmospheric bypass valve. Stock is recec and the forge is atmo.
Stock is always recirc. It is called a bypass valve (BPV), because it recircs back to upstream of the turbo, so that no metered air is lost (doesn't mess with your MAF-measured amount of air being sucked/blown to the motor. Your Forge is a blow-off valve (BOV), because it does not recirc this metered air back to the intake. How does your tune account for both? That does not make any sense to me. If your tuner says it does and can't explain how to you in layman's terms, then he's full of it.
The cruzes maf looks for the air to be recirc. It uses a maf and map. After 10 lbs or so it just uses maf. My tuner said the maf on a stock tune is expecting air to go back against it. When tuned its put in to not throw a cel and compenstate for the air not being recirc. I disagree with it being called a bov. Its still a bpv its hooked right on the turbo. Isnt a bov on a charge pipe? There is no available bov's for the cruze. They only have a recirc bpv or atmo bpv. This is my understanding, i could be wrong tho.
 

CT8

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15,408
Location
Idaho
Originally Posted by maxdustington
Originally Posted by CT8
Suddenly? You made serious modifications. I gave up on modifying anything I own 40 years ago.
Even your house? Modded cars are the things dreams are made of.
Nothing! Over the year I have bought fixer up houses to turn over .Worked on anything from Semi trucks to fork lifts for a living and done enough hot rodding cars and boats to say nope been there done that and I have had enough.
 
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