tomj77

iTrader: (2)

Can anyone tell me how to bypass the boost solenoid so I can run my bpv from the intake manifold properly, cause when I run it straight to intake mani, it is super loud and I get compresser surge a bit under lower load. Reason I want to do this is because my bpv is opening when it shouldn't be opening. at little lower rpm sometimes it opens when I get to about 10psi for a second making me loose 4 pounds of boost, and If I keep on it it will keep doing that so it wont boost any higher. I totally bypassed it and the issue went away, I know exactly how to cause the issue so I know it went away. some it must be something to do with my vacuum tank or the fact that I have the one hose from the solenoid coming from the mani instead of the chargepiple since my charge pipe has no nipple for that. thinking of installing one. I know solenoid is good cause I just replaced it with no change in issue. its pretty annoying already. so please help me.

Frogstofall

iTrader: (1)

I think in the, "How To" section there is a thread with instructions on how to eliminate the vacuum tank. That might be what you are looking for.

tomj77

iTrader: (2)

Just hope I don't have the surge issue without it, seems the spring I have in the bpv is to stiff, and idk what happened to stock one, so can't put that back in

tomj77

iTrader: (2)

ok I tried this and it doesn't work, get compresser surge cause bpv wont open fast enough. how do I fix this

Sevensix9

I'll post pictures of my setup once i'm not so hung over....


-Alex

Sox-Fan

iTrader: (7)

see ya in a month Alex.....

SSlobalt

Are you saying you have both ports of the solenoid hooked to the intake manifold or you have one of the ports open or blocked-off? I don't really understand what you are saying, there.

tomj77

iTrader: (2)

I had both going to the intake mani the top and bottom one when I bypassed the vacuum tank. I'm assuming the top port is to send excess air into the intake which is why it normally goes back into the charge pipe normally, and the bottom one is for vacuum to open the bpv which is why it's connected to the vac tank. Since I can't put top one to charge pipe anymore, I had to put it to intake mani. It all works fine when I bypass tank except its like there is not enough vac to open bpv on light acceleration. I put in stock spring today so see how that works , if all else fails ill get a new vac tank, cause I'm sure something in there is malfunctioning

tomj77

iTrader: (2)

well I put in stock bpv spring and it solved my flutter issue. now my tank is removed cause there is something wrong with it. im sure the check valve inside is failing. bpv sounds better and a little louder. and there are 2 bolts on the canister, not one like people say, its a pita to get at the one.

tomj77

iTrader: (2)

well surge isnt 100% solved, more like 95% there sometimes. but the constant blowoff with every twich of my foot is gone, yay, that was so annoying

SSlobalt

I'm glad you found your issue, but you didn't even mention that you had a BPV spring that was different than stock.

From GM ..... Read part thats bolded


Service Information
Home Publications Number Search New Bulletins Bulletin Search Feedback Help
2009 Chevrolet Cobalt | Cobalt, G5 (VIN A) Service Manual | Document ID: 2324723
#PIP4669A: Intermittent DTC P2261 Setting - (Aug 10, 2009)

Subject: Intermittent DTC P2261 Setting

Models: 2008-2010 Chevrolet Cobalt SS
2008-2010 Chevrolet HHR SS

This PI was superseded to update model years. Please discard PIP4669.

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 vacuum 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.

tomj77

iTrader: (2)

This is good post, how do I make vacuum to test it lol. I took it off already so should be easy, maybe a vacuum would work lol or plug it into the car again

tomj77

iTrader: (2)

old thread. but im pretty sure the vacuum tank is there to make bpv open faster. cause the lnf doesn't seem to be able to pull vacuum fast enough when u let off throttle to open bpv or bov fast enough before some air hits compressor fins. this is my conclution on a whole lot of fiddling around. I think im gonna end up going back to the vacuum tank eventually to solve issues with bov and bpv flutter. yes I am running both at the moment, bov just don't open fast enough at lower boost , bpv takes care of that. but even with that there is still flutter in the mid range sometimes. why does this car produce such shitty slow vacuum pull.

Shanedude

Is this BOV you speak of the Forge VTA? Or another aftermarket in the charge piping system?

tomj77

iTrader: (2)

its the zzp cp and bov. 19" spring is to stiff, 12 " spring keeps bov open at idle and still a little stiff. bov open at idle causes fuel trim crappiness. im sure a maf relocate and proper tune would fix that, but I don't got one now. running bpv and bov seems to work best lol

footballplaya3k

iTrader: (1)

Running both with Trifecta's ECP tune seems to the the best route for people wanting a BOV. What tune are you on Tom?

tomj77

iTrader: (2)

ecp tune 23 psi. fuel trims are pretty off though, still trying to get them dialed in. trifecta is pretty busy it seems. plus iv had other issues pop up. coupler not staying on, then my evap system not working messing with my trims and a/f ratio. just pain in the but. and im running opel injectors so that's gotta get dialed in.