It sounds like the BOV setup is trash. The tune probably needs a lot of help.

Give us pictures of the setup.

P.S. the car wasn't tuned to 5 psi. 5psi means it's in limp mode.

 

Ill get pictures today and post them up! Thanks for the quick reply. It needs tuned very badly. I also find out that 5 PSI usually means limp mode haha.

 

As stated above , it's likely not a 5 psi tune, but rather in limp home mode. I think the wastegate spring creates up to 5 psi, and the ECM doesn't actuate the solenoid at all, so it's all mechanical up to 5 psi. ( i may be wrong)
The setup you are describing with a MAF connected in the air box, and a blow off valve that vents to atmosphere is a big no-no. that's why it's running rich and exhaust pops on shifts.
(i have a catless downpipe with no muffler and it's normal for the exhaust to "gurgle" and even pop ocasionally, especially when cold on the 1-2 shift, but if it's more than that, and with ur setup it probably is, and its bad... mkay...)
I've heard of people running speed density tunes on these engines, by forcing it to ignore the MAF, and running off the MAP sensors only, i guess that's possible (something about disconnecting the EVAP ... something... forces the ECM in Speed density mode) but odds are that's not what's going on.
One way to fix it is to go back to a BPV, remove the BOV and put a block off plate there, that's what i would do, OR do the BOV setup correctly but i feel that is more tuning and headache than u care for.
Also 15 PSI is the factory boost setting, not necessarily a bad thing.

The stutter at high RPM is definitely a bad thing, and its too early to tell what it could be.
Id say step 1: fix it mechanically, figure out how you want to solve this BOV problem, see what other mechanical problems it has, maybe a set of spark plugs? who knows?
step2: Figue out the tune, is it a factory tune? did someone mess with the MAF calibration? who knows.

You said you work for a dealership, excellent opportunity to bust out the troubleshooting tools, and go record a few things during a drive. Car is equipped with a wide-band O2, so get those dealership tools out, and go log the primary O2 sensor during a WOT. or borrow / buy HPTuners if you plan on playing with it in the future. You could return it to stock, and flash the original tune into it since you work at a dealership.

EDIT: this "no CEL" thing bothers me, someone may have turned off a bunch of codes in the tune. You should read codes anyway, maybe its a code that hasn't lit the CEL yet, like one that takes 2 key cycles to light the CEL.

 

If it was me I would get HPTuners, then send logs to a reliable tuner like Terminator 2 and see what he says. I'm guessing codes are turned off in the ECU and it's running like ****.

Compression on all 4 cylinders will give you a good guess if you have a chance to revive the beast to normal.

 

i agree with you umrdyldo, i'd ask him to post his controller read-all, and logs here using HPTuners, but i didn't want to push HPT if he doesn't want to spend the money. so im trying to think of alternatives.

 

Alright, so i got some pictures last night after i got home.

This is obviously how he has the BOV routed. Theres a bolt plugging the one vacuum line if you look closely. He said its set up to not recirculate air & thats one reason a CEL gets thrown.


One of the vacuum lines off of the BOV going to the block i do believe.


This is where the MAF sensor is located still. Stock placement or?


Does have a Hahn block off plate for the BOV. Just showing you guys that.


Another picture of the BOV


This is one of the MAP sensors. Theses are stock right? He stated he had the GMS1 but i think he's just talking out of his ass on this one. This car was awful. It looks 100x better from just a few hours of cleaning. It looked like a squirrel lived under the hood for 2 years.


Anyway, those are the only ones i took. Its back into limp mode at the point. I got the codes cleared yesterday just so i could see if it would throw a CEL & give me the most recent ones. Well, the CEL is back on so I'm going to get those read today. Before i cleared there was a Cylinder 3 misfire(i believe i know what it was from which was water got into the spark plug chambers somehow?) And a code about the EVAP, which he said gets thrown all the time from the BOV being set up like that & not recirculating.. For the most part it runs fine, but i can't wait until its 100%. I will be getting an HPTuner soon. I don't have access to a Tech2 (GM scan tool) or anything like that right now. Thanks guys, i hope we can get it back to normal.

 

plot twist. Porous block

 

Boy I hope that's not true. You shouldn't have water in a cylinder.

Especially the cylinder with the same misfire. That would be bad.

Also, I noticed the PCV hose on the intake is messed up. Looks like he broke it at some point.

 

those look like stock 2.5 bar MAP
that is the factory airbox with factory MAF location
I'm not driving my cobalt now but i'll have to compare your vacuum hose set up to my stock one, but that'll be in 2 weeks.
Or someone else on the forum needs to do that.

Misfire on cyl3 is problematic; compression test as suggested might be a good idea.

Personally i'd return the car to stock BPV setup.

 

I believe it was from cleaning the engine bay. Some water seeped past the coils & down around the spark plugs. Cleaned everything out very good & back to new with that. Car does not lose any coolant. So no porous block

 

Sounds good. I'd really like someone to compare ASAP so I know it's okay like it is. Like I said above, I believe water was from cleaning the engine bay. It desperately needed done, and I'll take extra precaution around the coils next time. So with all of that I'm still stuck with the stutter problem & limp mode..

 

Routing should be done like this thread
https://www.cobaltss.net/forums/forc...thread-204185/

Looks like yours is routed very wrong.

 

I can't tell where half the vacuum lines are going in that post. For the most part mine are the same. I have the block off plate though.

 

well, not only is that write up vague as to where those hoses go, but it also has the same problem you have.
If you read the thread, they talk about throwing codes, and running rich, so that's not your answer.

I dont know enough about all those vacuum lines, what is that solenoid on the intake that has 3 dfferent vacuum lines and an electrical cable running to it anyway?

In your pics, that twisted pair by the firewall, what is that? where is it going, that's not factory.
As someone else mentioned, that nipple on the intake tube, downstream of the MAF sensor, it was broken then someone tried to repair it, make sure that's not still broken / leaking as well.

Aside from all this: WHAT IS EVERYONE OBSESSION WITH RUNNING BOVs ??? WHY IS EVERYONE INSISTING ON MAKING THINGS WORST BY RUNNING BOV when the car was not designed for it, and they don't do it properly. Freaking juvenile, "I wanna hear the PSHHH man!" ... idiots. Do it right or keep your hands off the engine.

Ok, i'm done now.

 

Best advice ive seen so far is to ditch that bov setup altogether. You can probably find a stock bpv and hotside pipe on here for cheap try mongorat first, or get a new charge pipe and forge bpv.

 

check this picture out on post 23:
https://www.cobaltss.net/forums/08-1...st-off-300390/

I have no idea what the "vac tank port" is, but the other 2 vacuum tubes are correct, i checked on my car.

I keep saying this like a broken record, but unfortunately it's the only advice i have; i'd undo everything the previous owner did, so you at least get yourself to a solid starting point.

 

Wow, thanks for the posts! I'm going to try putting it back to stock & see how it goes. Honestly, I think that there's just a BOV on there with no tune.. Do I need a MAF relocate, if so is there a DIY? Thanks a lot for the help. I'll be updating thoughout the weekend

 

If you are putting it back to stock, which I would recommend, your maf location is already in the stock location so no you don't relocate it.

 

if u want to return to stock , your MAF is in the right place. Make sure that the glued on nipple downstream of the MAF is not leaking air. I'd check the airbox as well ... maybe the previous owner removed the filter for the 50 extra HP someone told him he'd gain... who knows at this point.

If you do want to set up a BOV setup, you NEED to tune for it, and you need to put the MAF in the cold side charge pipe, from intercooler to throttle body. I think ZZP has an aftermarket charge pipe that has the necessary port to put the MAF there, they also sell a cable extention so the connector can reach. Some of the concerns with putting the MAF in the charge pipe 1) it's exposed to higher temps post turbo, so the MAF may be scewed, or maybe break? 2) the different location will need to be tuned for the different airflow pattern, maybe different pipe diameter, etc.

3 people have suggested returning to the factory BPV setup now.
I guess i should have asked this at the beginning, what do you plan on doing with the car? If you're planning on a 450 HP car, our suggestions might be different, if you want a stock or around 300 HP car, then i'd say just return to stock BPV.

Disclaimer: I'm trying to help but my experience is limited, i've had my cobalt for 2 years, did a mild tune with HPTuners myself, but that's the extent of my knowledge. you could get some better advice from more experienced people.

Did you do a compression test? you mentioned some other problem with EVAP where did that lead? boost leak test? I'm guessing you have multiple problems not just this BOV thing.

 

Alright guys, reviving an old thread here. I FINALLY figured it out & it was so simple, go figure. The kid I bought it off of bought 4 new plugs for the car & I installed them. They were NGK I believe. Anyway, searched around & found a few threads about aftermarket plugs. Threw in some ACDelco platinums today & she's good as new. Holds boost, spikes 16psi & no CEL. Crossing my fingers. Also cleaned the MAP sensors.

 

I have never heard of the car going into limp mode from Bad plugs

 

Yeah you're telling me. There are zero problems though & it's the only thing that I did. Not sure if the gap was that far off or what...