Thought this might help some people .


Service Information
Document ID: 2298191
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#PIP4669: Intermittent DTC P2261 Setting - keywords air boost cac charge chevrolet control cooler driveability ecm engine gas hole intermittent inf low maf map mil pipe power reduced reducedpwrmde ses turbo - (Jul 7, 2009)


Subject: Intermittent DTC P2261 Setting


Models: 2008-2009 Chevrolet Cobalt SS

2008-2009 Chevrolet HHR SS




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
A technician may find DTC P2261: Turbocharger Bypass Valve Stuck Closed set with no problem found. It may be intermittent in nature or they may find the dtc will set after a hard acceleration, usually in third gear. DTC P2261 is a type B dtc and will not set on the first drive cycle the dtc sets, therefore multiple test drives should be performed to confirm repair.

Recommendation/Instructions:
SI diagnostics for this DTC states that the ECM compares the measured MAF reading to the modeled MAF and has detected a series of pulsations in the induction system that exceed a calibrated threshold. A snapshot of "Induction Data" will show the fault, however the tech may need to compare the snapshot data to another vehicle if they are unfamiliar with the readings. They should note a fluctuation and or a difference in the desired versus requested boost level. When diagnosing this dtc pay close attention to Circuit/System testing step #1. This step has you inspecting for any vacuum leaks, damage, restrictions, improper routing or connecting of the vacuum hoses on the charge air bypass valve solenoid, the charge air bypass valve, and the charge air bypass valve vacuum tank.

We have found leaking vauum tanks causing this dtc. When testing the vacuum tank, care must be used or the results may not be valid. The vacuum tank has an integral check valve not noted in SI. To check the Vacuum Tank operation, disconnect the hose that runs from the tank to the Bypass Valve Solenoid at the solenoid and apply vacuum to the tank. The tank should be able to maintain vacuum with no decay. Note: If you remove the vacuum hose from the intake manifold and plug it and the decay stops the check valve is leaking, if the decay continues the tank itself is leaking.

Note: Front wheel drive platforms using the 2.0 Liter RPO (LNF) incorporate a charge air bypass valve supplemental vacuum tank. The purpose of the tank is to provide an instant source of vacuum to the bypass valve via the bypass solenoid (when it is commanded open by the ECM). This results in less pressure buildup under closed throttle conditions, thereby reducing compressor noise, surge and spool time.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

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in lay mans terms what does this mean?

 

I've gone cross-eyed.

 

I removed that tank and i got no issues with my aftermarket bov set up.

 

ive removed the tank on the stock BOV, actually holds boost better without the tank. similiar results as the Dejon spring but with out the surge issues I had with the spring.

 

So what would removing this tank do for my car, and where is it located?

 

which tank?

 

That is what I wanna know!!

 

if you look at the boost bypass valve solenoid, u will see one tube coming off the front solenoid and one tube coming off the intake manifold and goin underneath the manifold next to eachother. the way the solstice has it and the way I put it was to make the manifold tube run directly to the solenoid. this bypasses the vacuum tank which can then be unbolted. sorry, but i have no pics at the moment. this is clear to me, lol.

the tank is directly under the intake manifold, easlily seen from underneath the car

 

Have had that code 3 times in 1600km lol

I just reset the code lol

Thanks for the info, all maybe get it checked out one day lol

 

Had it happen again....at 2500km, went to dealership.

They checked it out, vacuum tank was leaking. Installed a new one, no problems anymore!

 

Im having this problem. im going to try and delete the tank and see what happens

 

just deleting the vacuum tank solves this? What purpose does this vacuum tank serve in the first place. With all the corner cutting GM takes, im sure they put it there for a reason

 

What negatives are there to this?

 

where is this tank and will a hks void this from being under war.

 

The purpose of the tank is to provide an instant source of vacuum to the bypass valve via the bypass solenoid (when it is commanded open by the ECM). This results in less pressure buildup under closed throttle conditions, thereby reducing compressor noise, surge and spool time.


Underneath the intake manifold.