twerner987

A lot... Bunch of stuff. I'm new here but I usually come here to look up problems I'm having but I'm having to much happen at once and Idk what's going on...

first off car is a 09 cobalt ss/tc stock besides Hahn cold/hot charge pipes no tune and no other bonuses I know have (bought used with 44k miles)

Errors..... 1) I'm blowing 3 codes at once. P0507, P0236, P2187. They all have a common thing the map sensor. My map sensor has a wire cut, in slot 2 which I believe is the IAT wire but I can't find where it goes (the other cut part)

2) when I first turn on the car it sucks in air like it wants to wake my whole neighborhood up... I've been told it's the air intake and a tune will fix it. Is this so? Also with the start up it isles around 1200Rpms till it's (warmed) up and drops to normal rpms but isles kinda hard.

3) when it's kinda warm outside (60-70) or so the cat likes to idle at 1200-1500 rpms when I come to a stop or put it in neutral sometimes to goes up and down other times it stays there and sometimes it just goes back to normal rpms but then right back up after the next stop. What's up?

4) my stoco BOV sometimes doesn't work, instead of hearing air release I just hear the turbo.

5) half the time my boost doesn't work sometimes I can barely get 6psi other times I'm a champ at 21psi.

I've checked for leaks and so have two other people. I've redone my charge piping twice now, took apart the BOV and cleaned it, cleaned the MAF sensor, changed the spark plugs (which are frying fast... I got cold stage 1 plugs ngk). I'm in some desperate need of help... I just wanna enjoy the car without stuff going wrong and I've taken it to Chevy and they are hopeless has every.... Two different places. First one gave me a new fuel pressure sensor... Waste of $100 and the other one had my car for 6 hours and found nothing (complained and yelled at the guy) no charge... Never go there again... please help. ( I know some stuff about cars I'm not a giant expert)

riceburner

iTrader: (66)

Welcome to the forum! I cant offer much advice other than saying the initial startup sucking is normal.

Snail_SS

iTrader: (3)

Well first off a 21 psi boost isnt stock, so the car is probably tuned, and if sometimes you hit only 6psi maybe you have a leak sonewhere.
im guessing by stoco you mean stock and its not a bov its a bpv big difference. Also yes at start up the intake will make lots of noise but should stop after a few mins when the rpms drop.

Although i dont see you have an aftermarket intake(unless you forgot to mention it) so as far a i remember with a stock intake I don't remember even hearing the turbo air releasing sound, so something might be wrong there

twerner987

15 is stock. But I got charge piping so 21. And I've stated I dint have a leak. And not tuned. Chevy dealership checked and cleared .

Snail_SS

iTrader: (3)

Never heard of charge piping changing boost, and specially so dramatically. I have all bolt ons and my boost has never changed and i didnt retune for IC and charge pipes just saying

twerner987

Idk then cause there is only charge piping a cut map sensor wire a lot of f-ed up idling and 21psi or 6psi..

Snail_SS

iTrader: (3)

Well i would start by fixing that map sensor wire then go from there some problems you have might be related just to that single problem. Is it the intake manifold map sensor or the lower pipe map sensor thats cut?

twerner987

The intake one. The 2nd wire. The IAT wire. I followed the tan wire from the MAF sensor but that leads to a connector right below the exhaust manifold

09outlander

The car probably has the GM stage 1 and a boost leak by the sounds of it. Changing the charge piping won't affect boost levels.

Snail_SS

iTrader: (3)

Exactly what i was thinking ^^

kdub1492

iTrader: (8)

Car has a boost leak, check all of the charge piping. It is also not stock, you wouldn't be overboosting unless you have a wastegate issue. Check leaks and get the car tuned by someone reputable. Also fix your MAF wiring

Shanedude

First off the loud sucking is normal, the engine revs high at startup for cat warmup procedure. And an after market intake multiplies this sound.

"6psi" is Limp mode. The car puts itself into this state when something is not right. It's not always a boost leak, it can be MANY different variables. Maybe your GMS1 wiring was soldered in shitty and that's what is causing the intermittent boost issues. It could be your fuel trims are exceeding the tolerated amount sometimes. It could very well be a boost leak too. Many things will cause this.

21 psi is more in tune with Trifecta/Hp. Stock is 15psi, GMS1 is 18psi. GMS1 can hit 21psi in certain circumstances(extremely high altitude, extremely hot outside) the car in stock/gms1 form will up the boost to maintain 260/260(stock), or 280/320(GMS1).

Do not use colder plugs on an LNF. Stock all the way. Stock plugs life are around 150,000km, I change mine every 75,000km cause it's easy and cheap.

Charge piping will not affect boost pressure like you've stated. It's a reliability/sound mod.

You need to get ahold of the previous owner. He has frankenstein'd that car. You do not know what after market tune he has on there much less what parts and it's ruining your car. If you can't contact him you should start researching and reverting it back to stock or near stock. Have GMS1 flashed back onto it, and the MAP and MAF wiring re-done. make sure you have the right 3bar MAP sensor with the proper o-ring(wrong Oring will cause a leak)

And get us a picture of that engine bay. LNF's don't have a stock BOV. They have a plastic BPV.

kdub1492

iTrader: (8)

The vehicle would not boost higher in warmer Temps.

Shanedude

So a cobalt sstc in the desert vs one in the winter would have the same PSI?

tomj77

iTrader: (2)

well first of all, before u even try to fix anything else, fix the cut wire on ur map, most likely that's where all ur problems are coming from. And no, charge pipe will not give u 21 psi. lol if ur boosting that high when its working ur tuned. fix ur map and then come back with whatever issues are still there. cant go trying to figure out issues when u have such a major one to begin with that u know of.

twerner987

It's not tuned. Lol Chevy dealership thought it was tuned to and "reset" it but said it wasn't tuned to begin with. I live in Washington. So weather here isn't really the best and I seem to get 21psi no matter the temp. As for Mr fixing the map sensor. I have the wiring diagram and it says it goes to the gray wire coming from the MAF sensor but I followed that wire and it goes to the plug below the exhaust manifold. And sorry it's the stock BVP. That plastic/rubber one attached to turbo itself. I guess I have to have someone else look for the map sensor wire. I spent like 2-3 hours trying to follow it unwrapping the wires and everything