Hello all.

Just got a Cobalt today. Its a 09 SS/TC with about 90k on her. Traded a '96 Jeep Grand Cherokee for her (I KNOW! WHAT A DEAL). This is what the previous owner told me:

all new aftermarket piping
larger innercooler
the boost goes in and out due to a seal
has a 3 inch high flow catless downpipe & 3 inch exhaust out the side
I have a new rear bumper, new side skirts.
larger throttle body
replacement turbo
suicide door kit
door popper kit
oil catch can
it's got newer good tires on it
it has angel eye and led headlights(WTF is angel eye?)
shaved trunk, all was being prepped for paint
a bracket for an aftermarket radio and a hidden antenna kit
aftermarket blow off valve
aftermarket front fenders with scoops
aftermarket front bumper, cowl hood scoop


LIKE I SAID, TRADED A 96 JEEP GRAND CHEROKEE FOR THIS THING. I THINK I GOT A PRETTY DAMN GOOD DEAL. WHAT DO YOU THINK?

he mentioned a boost lost due to a seal... im no master mind mechanic but it doesnt sound like it will be something as simple as a seal. Sometimes i get boost, most times I dont. and when i do get boost, i open get maybe 3-5, nothing over 5 though.

ANY HELP?

 

CEL codes? definetly have some kind of boost leak.

 

Boost leak. I bet its from the "aftermarket bov"

 

Yeah thats what a friend told me, probably the aftermarket bov. I work midnights and traded just before work tonight so didn't have time to check it out. Will be doing so tomorrow morning as soon as I leave work. Thanks for the help so far.

 

Is this the one from Craigslist titled as a project car in trenton?

I tried to trade my seats + cash with that guy

 

yeah it's the one from Trenton. traded him a Jeep I paid $1500 for and put maybe $1500 into it.

 

man, I wanted those seats haha

 

Welcome to the forum. In BIg Rapids here

 

Pics?

 

Thanks for the welcoming. And no pics as of right now. Will upload them tomorrow. Still trying to figure out the boost leak.. I realized, when I first start the car and let it warm up, I get minimal boost(3-5lbs...I think I hit 7 or 8 at one point) but then after about 5 minutes, no boost. Turn the car off, turn it on, hello boost for 5 minutes. Not getting used to that, just tested it for self knowledge. I dont know what it is. Gonna have a fun day tomorrow trying to fix this thing.

 

checked and retightened all the couplers, intercooler/chargepipes dont have any cracks or holes, although i wasnt able to check the cold side connection to the intake. i wasnt able to get to it, but it doesnt seem to be an issue.

I had a buddy of mine check it out and he found the BOV setup was hooked up wrong and there was no vaccum hose to the turbos nipple on the left side. We ran up to auto zone and grabbed some vaccum hose and a tee splitter and hooked it up correctly based off of his setup, and studying numerous pictures of setups with&without BOVs. It definitely made a big difference, considering afterwards, the turbo flutter seemed to die almost completely. Were catching boost 99% of the time at the beginning, but it seems limited to a rough range of 6-12psi, but after a few seconds there's nearly always an immediate loss of power, it '2 steps' (not really, but sounds alot like it,) the PSI holds in that 6-11 range, & sometimes drops..
He decided to hook his computer up to the OBD 2 and check for codes. There was no CEL, but P0101** showed up. He cleared it had me go for a test run to watch the number readings from the sensors. He could only essentially grab the Intake MAP in realtime which never seemed to fluctuate under the the conditions. The Intake MAP read a max of 29.73psi (on a pull) and sat about 3.77psi at idle. On second/third gear trials (ran 6-8psi boost) the Intake MAP read average 24 psi, and baring constant through that '2step' condition. I'm not so sure if that would even fluctuate under boost leak considering its just intake map..? just guessing.

It seems on the first pull after start up it boost fine, although limited to about 11 or 12 psi, it pulls, but it seems as though the computer catches it and compensates..
He had me whomp on it (which is where i got the 29.73psi intake reading from), and after pulling about 9 psi of boost it '2stepped', boost/power-loss, & threw the P0101** again. The Intake MAP psi read & remained within 29 psi throughout the power loss. Mass Air Flow rate maxed at 36.8 lbs/min.

Although the turbo flutter is almost gone after the tee fitting and vacuum hose fix, it still makes some odd airflow noise when i shift. If i had to explain id say it sounds alot like airflow sucking through the air cleaner when someone floors it, only just for a second, and it dies off immediately. It nearly overpowers the sound of the BOV..
I've read online the actuator nut on the back of the wastegate could have come loose. Sound possible?/if so, Where exactly is the wastegate located? I've read about the MAF/MAP sensors needing cleaning, im not so sure about that considering we got some good readings from the computer.. or didnt we? Is it possible the PO replaced the sensors and the car needs a retune? They arent BOSCH sensors which i think BOSCH are GMS1.. so sensors look stock, so I'm not sure about the retune. Could they just be bad? We didnt get any cold side sensor readings, just the Intake MAP. Could the catless downpipe be causing this? All input is appreciated.

 

Yup you have a boost leak

 

Make a boost leak tester P0101 is always indicative of a boost leak.

 

Welcome to Cobalt land, Once you enter there's no escape.

 

for you and all the others saying "its a boost leak."

-took it to a local performance shop today. got a full diagnosis on the car, and they ran a boost leak test for me. Pushed 21lbs of boost with no leakage of boost. Checked all the sensors, and they all checked out good. Being told that due to the mods to the car under a stock tune, its putting the car in some sort of Limb Mode. So taking it ASAP to a different performance shop, ZZP. Hopefully after the tune we'll be up to par.

 

Welcome

 

was able to take it to zzp here in Wyoming, MI. the guy made me a custom tune for my car since the previous owner put some, "different" physical mods on the car that zzp hasn't seen before. so after upgrading to LDK injectors & about 30 dyno runs it was pushing 31psi @ 305bhp in 3rd. he tuned it down a bit for a nicer fuel/air ratio that ran 29.3psi @ 299bhp in third. on the ride home it was apparent that this was a custom tune when the needle bottomed out 30psi in 4th & 5th.

 

I'm really hoping that's not on the stock turbo. I can't imagine ZZP would do that