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'12 Regal 2.0 Turbo surging at mid - high RPM

teebore

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2012 Regal 2.0 Turbo
Hello all, Im currently experiencing some very annoying surging in my 2012 Regal. Its the 2.0 Turbo auto 98k, with the Stage kit and Trifecta tune. Both the Stage kit and tune have been installed for 20+k so I don't believe its related.

The car idles and starts just fine. When not hard on the boost it drives normal, no perceptible surging. It seems that 2500+ RPM + boost is when it starts to surge. I have cleaned the MAF and inspected for boost leaks. Its throwing no codes. I even made the mistake to taking it to the local stealership in hopes they would be able to find/fix the issue. $200+ later all they could tell me is that it isn't the MAF (they swapped) and I would have to leave it for more than a day to continue diagnosing ($165/hr). I hooked my logger up and recorded boost + throttle level and it would look like at full throttle boost is peaking at 20psi and dropping right away to 11psi then back up to 20, wash rinse repeat.

Bad blow off or wastegate? Any ideas or additional diagnostic steps would be greatly appreciated.
 

CoyoteEcotec

Active member
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Buick Ownership
2016 Regal AWD T
Hello all, Im currently experiencing some very annoying surging in my 2012 Regal. Its the 2.0 Turbo auto 98k, with the Stage kit and Trifecta tune. Both the Stage kit and tune have been installed for 20+k so I don't believe its related.

The car idles and starts just fine. When not hard on the boost it drives normal, no perceptible surging. It seems that 2500+ RPM + boost is when it starts to surge. I have cleaned the MAF and inspected for boost leaks. Its throwing no codes. I even made the mistake to taking it to the local stealership in hopes they would be able to find/fix the issue. $200+ later all they could tell me is that it isn't the MAF (they swapped) and I would have to leave it for more than a day to continue diagnosing ($165/hr). I hooked my logger up and recorded boost + throttle level and it would look like at full throttle boost is peaking at 20psi and dropping right away to 11psi then back up to 20, wash rinse repeat.

Bad blow off or wastegate? Any ideas or additional diagnostic steps would be greatly appreciated.
Check your wastegate.
  • Ensure that the retention clip (1) is in place. If the clip is missing, install a new clip.
  • Use your fingers to wiggle the wastegate pivot lever (1) back and forth.
  • If the lever wiggles with little effort while the actuator rod remains static, the pre-load is insufficient.
  • If the inspection failed, replace the turbocharger. Refer to the Turbocharger Replacement in SI.
  • If the inspection passed, continue diagnoses.
 

teebore

New member
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Buick Ownership
2012 Regal 2.0 Turbo
Check your wastegate.
  • Ensure that the retention clip (1) is in place. If the clip is missing, install a new clip.
  • Use your fingers to wiggle the wastegate pivot lever (1) back and forth.
  • If the lever wiggles with little effort while the actuator rod remains static, the pre-load is insufficient.
  • If the inspection failed, replace the turbocharger. Refer to the Turbocharger Replacement in SI.
  • If the inspection passed, continue diagnoses.
Hello, I followed the above steps and the inspection passes. Do you have additional diagnostic steps?
 

srund

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Coils? I had surging under heavy throttle, 3500-4000+ rpm's. Checked everything I could think of and then at the suggestion of a tech I replaced my coils...110,000 miles on originals. Took care of my issue.
______________________________
 

BoostedRegal2.0

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2014 Regal 2.0 Turbo AWD Trifecta Tune
My car was doing that and I replaced the camshaft timing solenoids and it fixed the problem. There's one for the intake and one for the exhaust and they are about $50 each.
 

CoyoteEcotec

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2016 Regal AWD T
Hello, I followed the above steps and the inspection passes. Do you have additional diagnostic steps?
I’m assuming you’ve already checked your air filter for excessive dirt, dead squirrels, chunks of hitch hiker etc. A visual inspection of your turbo would be the next diagnostic step. Look for any cracks in the housing or damage to the impeller itself. Also reach in there and push on the impeller.(engine off and cold! 🤣) If it flops around then you know the answer. Also look at spark related items like srund mentioned. Coils, plugs could both be suspect at your mileage. I’ll pull the specs on those and your VVT solenoids so you can check them out before throwing parts at it.
 

BoostedRegal2.0

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2014 Regal 2.0 Turbo AWD Trifecta Tune
My cam solenoids were clogged with dirt and sludge, so a visual inspection of them will tell if they are bad. The solenoids use oil flow to either advance or retard cam position, and if they are clogged they don't function properly. There is only one small screw holding each one in place and they are right on top of the motor, so it takes a few minutes to pop them out and inspect them.
 
Last edited:

BoostedRegal2.0

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2014 Regal 2.0 Turbo AWD Trifecta Tune
Here's a picture of what they look like. Oil flows through the small rectangular slots in the sides, and they get clogged after tens of thousands of miles.

cam solenoid.jpg
______________________________
 

CoyoteEcotec

Active member
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2016 Regal AWD T
My cam solenoids were clogged with dirt and sludge, so a visual inspection of them will tell if they are bad. The solenoids use oil flow to either advance or retard cam position, and if they are clogged they don't function properly. There is only one small screw holding each one in place and they are right on top of the motor, so it takes a few minutes to pop them out and inspect them.
They can fail internally so a visual inspection isn’t the only aspect but you’re right that’s a good start.
 

teebore

New member
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2
3
Buick Ownership
2012 Regal 2.0 Turbo
My cam solenoids were clogged with dirt and sludge, so a visual inspection of them will tell if they are bad. The solenoids use oil flow to either advance or retard cam position, and if they are clogged they don't function properly. There is only one small screw holding each one in place and they are right on top of the motor, so it takes a few minutes to pop them out and inspect them.
Thanks for the tip. I removed and inspected; they have a bit of gunk on the screens, but nothing major. I cleaned and reinstalled to no effect.
 

teebore

New member
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3
Buick Ownership
2012 Regal 2.0 Turbo
Coils? I had surging under heavy throttle, 3500-4000+ rpm's. Checked everything I could think of and then at the suggestion of a tech I replaced my coils...110,000 miles on originals. Took care of my issue.
Did you car throw any codes or check engine lights?
______________________________
 

teebore

New member
7
2
3
Buick Ownership
2012 Regal 2.0 Turbo
I’m assuming you’ve already checked your air filter for excessive dirt, dead squirrels, chunks of hitch hiker etc. A visual inspection of your turbo would be the next diagnostic step. Look for any cracks in the housing or damage to the impeller itself. Also reach in there and push on the impeller.(engine off and cold! 🤣) If it flops around then you know the answer. Also look at spark related items like srund mentioned. Coils, plugs could both be suspect at your mileage. I’ll pull the specs on those and your VVT solenoids so you can check them out before throwing parts at it.
No missing hitch hiker to be found, not even a dirty one, lol. I'm a bit over in the plug department, so I will prob try those next. If a coil was crapping out wouldn't it feel like a misfire and throw a code?
 

CoyoteEcotec

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2016 Regal AWD T
No missing hitch hiker to be found, not even a dirty one, lol. I'm a bit over in the plug department, so I will prob try those next. If a coil was crapping out wouldn't it feel like a misfire and throw a code?
Coils can go pretty far past bad before they throw a misfire code. I’ve replaced hundreds of them that never threw a code but were causing acceleration issues. You can measure the resistance and figure out pretty quick if it’s damaged and by how much so if you have an ohm meter. BUT if your cam solenoids had gunk on the outside it’s probably a safe bet that there’s more on the inside and they’re pretty sensitive.
 

CoyoteEcotec

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2016 Regal AWD T
If the sensors outright failed, wouldn't they throw error(s)?
Missed this one. If they failed completely, yes. Basically the ECM could be commanding it to advance and it is advancing but it’s slow. Slow enough to cause a drive ability issue but not slow to enough to throw a code... yet.
 

BoostedRegal2.0

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2014 Regal 2.0 Turbo AWD Trifecta Tune
A coil failed recently on my wife's Regal and it threw a misfire code so it was replaced. It happened while she was driving, the motor started running rough and the CEL came on.
 

teebore

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Buick Ownership
2012 Regal 2.0 Turbo
Coils can go pretty far past bad before they throw a misfire code. I’ve replaced hundreds of them that never threw a code but were causing acceleration issues. You can measure the resistance and figure out pretty quick if it’s damaged and by how much so if you have an ohm meter. BUT if your cam solenoids had gunk on the outside it’s probably a safe bet that there’s more on the inside and they’re pretty sensitive.
KK, thanks; I'm going to check them when I replace the plugs. Do you happen to have the acceptable resistance range? Seems like a cheap item, maybe I should be proactive and order a set to save myself some sanity when I break one taking it off, lol.
 

CoyoteEcotec

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2016 Regal AWD T
KK, thanks; I'm going to check them when I replace the plugs. Do you happen to have the acceptable resistance range? Seems like a cheap item, maybe I should be proactive and order a set to save myself some sanity when I break one taking it off, lol.
They’re $23.79 a piece from RockAuto for the AC Delco. If it’s in your budget I don’t think it’s a terrible proactive mood at your mileage. I can’t find the exact number on the specifications for those coils. I think it’s .75-.8 ohms on the primary and 10k-11k on the secondary windings. If I find something different I’ll edit this.
 
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