Also, can you give me your vac reading at idle?

I swear you have a leak, so it will be around 10-15, I'm presuming. If you have no leak, it's usually around 19-21.

 

the vac reading is right around 15 and when i go full throttle it boosts to 10 psi in nuetral today it seemd much more smokier so lots of black smoke

 

Ok so I drove the car some more and got it to throw a code and went and had it read out.It appears I am misfiring on all 4 cyclinders. A couple guys suggested since the dealer had just did all that work they must not have hooked something up correctly such as a ground for engine position sensor which would explain why it gets burst of power and acting normal for a second.Now that I now its misfiring on all 4 I need to get the dealer to come tow it for me because its a 40 min drive providing they will fix it since they did all this work not even 50 miles ago.

 

I hope you get if figured out. Misfires might be from the rich running. The 10 psi of boost in neutral is a bad TMAP sensor. The 15 in/hg at idle is a vac leak.

 

Well thanks for all your input bro. I am hoping this comes out to be the dealer.A I noticed they took out the ECU and others parts because the bracket for the ECU was loose as hell and they broke the bracket for the coolant tank and never einstalled the nut holding it in. It seems thery did a sloppy job and with all thats involved to drop the trans axel by looking at my haynes manual I would hop that this turns out they didnt hook something up properyl or they pinched a wire . Just wierd I was able to make about 20 or 30 miles before seeing these symptoms but then again I only got on the throttle real good once. but thanks again this is yet another learning lesson on my car so thanks for the knowledge drop!

 

So I took the car into the dealer and they came to the conclusion of an o2 sensor being bad and dumping mass amounts of fuel causing the mis fires. so we will see

 

Keep your fingers crossed.

 

Got the car back today and so far the car runs mint after they changed the o2 sensor just wierd how it went like that just as they worked on it, seems shady...

 

Good to hear you got it fixed. I'm not a big believer in coincidences like that, but hey, it's fixed.

 

That's great man! I was hoping you'd get it figured out, Yeah, That def seems a little too shady the way this all happened, But any who glad your fixed up!

 

Thanks guys! yeah you deff. have to keep your guard up when going to the dealer for anything, heard way to many bad stories ha.

 

So ironically I have a very similar thing that happened to me just recently. Got some help with the tranny from the dealer a few weeks ago, car starts acting weird in light throttle conditions (idle, and low vacuum or in boost seems fine), and I got a P0130 the other day. I'm considering swapping the O2 sensor now.

 

Yeah that is wierd but give that a try hopefully that fixes it.

 

I have had the same problems and the dealer said it was the o2 sensor. It is not the o2 sensor I replaced it 3 times lol. What I did was buy a CEL scanner from AutoZone and when I go into limp mode 5lb psi max I just erase the code. And everything is normal again, but every once in a while it will come back but it won't throw a code on the dash. You can tell though when it comes back and just erase it again, with the scanner.
I'm not sure what the main cause is but I read on other posts that it could be the 3 bar map sensors needing soldering or crimping...

 

Yeah for my car the o2 sensor made sensor because they got a code or something or fuel something at acceleration and cruise and the misfires were due to mass amounts of fuel being pumped into the cylinders but we will see I wont be able to drive my car for a month so I will let ya know in a month lol

 

Well I haven't had my car go limp, but in my case the car seems to have uneven acceleration, and stutter or buck when cruising at constant RPM/speed. Perhaps I've sprung a boost leak, but the fuel trims haven't reflected that so far.

 

I am having a similar problem. Once my car is warm, over 160 degrees, and you get on it hard, it kicks into limp mode. I can run it as hard as I want when its cold, but once its warm, it does that. I put a new barometric pressure sensor and a maf on it. It is throwing a code about the correlation of the throttle position though, and a vent valve solenoid.

 

I am having an issue with my 06 cobalt ss/sc. I just replaced the cylinder head timing components and all kinds of stuff, inicially the car was having a misfire after the dealer replaced the catalytic converter. After i did that two days later it blew out the cyl 3 spark plug. I had a timesert put in but blew that out 3 days later. Hence why i had to do a new cyl head. Car has been driving great for the last week until today it started misfiring again on cyl 3. Got code p0303. Has new plugs timing is dead on new coil packs and new head with a valve job. My question is can a bad cat cause a misfire like that, but it only happens when im over 3 lbs of boost.....