find someone with a pressure plug or a smoke machine....

 

When the car is off and I unhooked the hose from the bpv and left it connected the solenoid, when I blew thru it, the air would go in, then not then in then not.

 

I don't know what the hell you just said there...

 

I was talking about the bpv solenoid..... I tried blowing thru the line with it still connected to the solenoid and the air would go in sometimes, and sometimes it wouldn't lmao

 

Well, I seem to have some of my power back. My lower map sensor was bad so they swapped the intake manifold sensor with the lower map sensor, just till they get a new sensor in.... The question is, why would There still be a fluttering noise coming from the intake? Would it be because the bad sensor is still connected?

 

Put your paper filter back in and see if it still does it.

Winner! btw.

 

Ok cool... I'll wait til they put my new sensor on then..... Also it still did this with the paper filter

 

As we said all along.

A P0236 and P0238 is almost always an issue with the lower MAP sensor. Mine was due to poor installation though, not bad sensor.

 

I still have the bpv flutter tho.

 

Did you do the vacuum tank bypass by chance? When i did it I got flutter when i bypassed mine .

 

I get a little of that too if I don't use my foot correctly. Like if I lightly let off or something.

 

I did the tank bypass and it still did the same....

After driving it tonight, it seems to be doing the same thing as before.... Builds boost like normal, but doesn't seem to pull...,, I dunno maybe it's just me.... I know that the bpv is still making a fluttering noise. My buddy is gonna swap some parts from his car to mine. What would you recommend that we swap? I was thinking the bpv, boost solenoid, wastegate solenoid, testing all vacuum lines, and possibly a boost test.... Does that seem like a good place to start?

Also, I just discovered that one of my screws that hold the maf sensor down is stripped and loose. Could this be part of the issue I'm having with building boost and not pulling like it should?

 

Man, you've been having some bad luck with your car. If that was leaking, you would probably be having AFR jumps or a stumbly idle.

 

Yes, the screws (only one screw is used on the 3 bar maps) hold the MAP sensor down. If that one is stripped the sensor could be loose which causes a boost leak and your wacky fuel trims. It will also cause the boost sensor codes. If you want a cheap easy fix get a slightly larger diameter self tapping screw and carefully tighten it down. it should fix your issues. Once you get it fixed. Unhook the ECM or the negative battery terminal and that will reset the fuel trims.

My car idled pretty well even with the huge crack I had in my Synapse IC LOL. Boost leaks tend to cause it to run rich even at idle. Rich idle is much smoother than a lean idle.

 

were the problems discussed happening at random times. I haveing same problems with my car, one day its perfectly normal. Next day it wont go above 5 psi, and that same day it could be fine again. I have no cel yet but when the car starts acting up i drive it as easly as possible.

 

Have you had codes read on the car? You are probably setting a DTC but no light.

 

the stripped bolt i was talking about was one of the bolts that hold the maf sensor in place on the intake.

 

I had a coworker plug his scan tool in, just a normol code scanner and it came back with nothing. Would the scanner that have at the dealershipe pick something up his wouldn't? I'm not to familar with code scanners and what all the can do but i have been thinking about getting one

 

well driving to work this morning car started acting up and popped a cel, i had someone scan it and it came back with P2261 if i remember correctly, wrote it down but left it at work. It said it was bypass valve etc. Well i was driving around in somewhat of a "limp" mode since its underpwered in this condition and i came to a stop sign waited and then pulled out and all power and boost was back like that. But a couple miles down the road it went back to its shitty old self. The cel has stayed on the whole time. I really hope the dealer can fix it once and for all. Anybody else get this problem fixed for good, if so what did the dealer do/replace so i can give them some info for a starting point at least

 

PI: LNF- Intermittent DTC P2261
Service Information
2009 Chevrolet Cobalt | Cobalt, G5 (VIN A) Service Manual | Preliminary Information | Document ID: 2324723
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#PIP4669A: Intermittent DTC P2261 Setting - (Aug 10, 2009)


Subject: Intermittent DTC P2261 Setting


Models: 2008-2010 Chevrolet Cobalt SS

2008-2010 Chevrolet HHR SS




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


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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 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.

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Š 2009 General Motors Corporation. All rights reserved.

 

new update on my car, got up to go to work sat morning and cel was gone lol. It still has issues. But when i started my car up to leave work you could hear the bypass vavle keep releasing. Im pretty sure it didnt do it before but maybe i never noticed it. It only does it on start up when the rpms are higher than idle to warm up cats etc. The car is going in tuesday. The cel that was on and then went away will that still be logged in the ecm for the tech to see it? Im just hoping they can fix this problem once and for all!!!

 

Please keep us posted. The more of these resolutions we spread around, the better our knowledge base will be.

 

will do, it seems like quite a few people are having similar issues, some are posted in different threads

 

deftinitely having this issue. I had the dealer replace the vacuum tank and it seemed to work for a bit, then the CEL came on again and it was surging pretty bad all over the place. I took it back in and they say its my K&N drop in filter!!! Hahaha. WTF???!!!

Where is that GM engineer? Help me! I'm not happy with my stage 1 right now.

 

Yeah that sucks..... Couldn't find any boost leaks again today...... I'm so close to putting the car back to stock and dumping it.... I don't even care how much I will lose.