I recently bought an 09 Cobalt SS. I have had it almost a month and i love it. This week, i have been experiencing a "flat spot", if you will, while aggressively accelerating. So this is what happens..... I am aggressively accelerating (not racing or using NLS) through first, then shift into second and u feel this extreme loss of power, and an abnormally LOW exhaust note. Once the rpm's reach 2500 to 3000 the power comes back, LOW exhaust note dissipates, and the car takes off....

Now i know some of you will say, "thats the turbo lag, and usually kicks in around 2500 to 3000 rpm's". No it is not. I am experiencing a loss of power, not wait before the power kicks in. And i am only experiencing it in second gear and only about once out of every 5 times i need shift from 1st to 2nd.

I did add a superchips flashpaque tuner, prior to this happening. The tuner worked great, almost made it too fast for my comfort. But i love it.

Any ideas as to what could be wrong? Is it the tuner? Why did it wait a week to act up if so? It almost feels like a loss of air to the engine, like a strangling feeling to the engine. Why would it act up if it is the tuner? What could it be if its not the tuner?

Im kinda wanting to have an idea of what could be wrong before i take it to the stealership so they can hold it for a week just to tell me everything work fine and they cant find anything wrong...... Please help...

 

Never heard of this in 2nd before; lots of people experienced this with the stock tune in 3rd however. I can't even remember what the thread was titled where it was discussed or I'd search through and help track it down.

 

ok well first off, welcome to the forums, noticed that this is your first post.

Second, do you have an aftermarket intake?

 

happens to me also i have superchips tune. make sure your car is fully warmedup before u start accelerating. if you notice when this happens to you. the boost is high in the 14-20 and the car barely moves. make sure you warm up your car before you can wot.

i wait till im in the 190's temp before i start to hit boost.

 

Now that u mention it, I do notice it more off of cold starts, and less after I have been drivin for a min. Why is that do u think? I hate to say it but it makes me feel better that it happens to u as well....thought I might messed somethin up.... or did we?....

To answer the other guy question (sorry I forget ur screen name, and I'm doing this from my phone) but know I do not have an aftermarket exhaust. I assume u were gonna say something about too much or too little back pressure. I had a problem with back pressure in a previous car, but that's not it, though it feels very similar. This is a more dominant power loss "feeling" than back pressure or lack there of.

And I'm sorry, I responded to u like u were talking about exhaust. No I do not have an af intake either....though I was planning on purchasing a Hahn CAI. Why? Would this cause a problem as well?

 

I'm not trying to be a butthole but why in the world are you at 2,500rpm when accelerating aggressively?? It should be a decent amount higher i thought.

Meh, anyways, sounds strange, defiantly let you car warm up before boosting. The engine is in warm-up mode for some time after starting. Also, oil has to be warmed up so it can travel through the engine ect, roughly 10 minutes before it can travel at the necessary speed to cool and lubricate the turbo and engine. Cold oil is too thick.

Just my 2 cents

 

I agree. Of course there's a "flat spot" until you rev the motor up a little. Just look at a dyno graph from one of the drivers on this site.

 

if you bounce off the rev limiter you will blow spark and this will cause the engine to sputter when shifting into the next gear. Had this happen to me at the track.

when the car is cold is does not like to be beaten on until the coolant is at 180*, otherwise you'll throw a flashing CEL

 

Well... im starting in 1st gear, i quickly take it up to 4000-ish rpm's, then shift to 2nd, which starts somewhere around 2500 rpm's and then the low base note from the exhaust and slow acceleration. Im not trying to race her while doing this, just driving quicker than all the normal cars at the light.

But yes i have noticed that it wasnt as cold here when i bought her a month ago, and didnt have this problem. Thanks for your input though.

That sucks to have wait that long to really get to drive your car. I have a 30min commute to work on the freeway. I drove her nicely to work this morning every now and then looking at the coolant temp. By the time i got to work it was only at 186*.... What is the normal running temp of Cobalt SS? I figured my commute would be ample time for heating up.

Yea, i have had the sputter thing happen to me a few time while really getting on her. Even a little multi backfire.... I assume this is from not doing the NLS quick enough? But this brings me to another question about the Superchips tuning..... I have mine tuned with the 91 Performance setting, with the Rev Limiter at stock, and the Speed Limiter Raised. I guess im not getting why anyone would take it off, it cant be a good thing to go further into the red than the stock limiter would let you, right? Wouldn't this damage the engine?

 

This may sound rudimentary, but do you have Trac Control on? It could be detecting wheelspin and cutting the power. Try it in TCS off or Competitive. I'm sorry if you've already thought of this.

 

Good point .

 

I was thinking it could be the silicone elbow (or whatever it's made of) on the AEM intake cutting off air supply. eh, I was just spitballing ideas. From what the one other guy said, sounds like it may be your tune, since the other guy with superchips had the same problem. like one person above me said, make sure you have traction control off too.

 

I've definitely had this happen during a failed NLS attempt with my tune, but never during a "normal" hard shift especially only to 4grand. I wonder if the torque management algorythm built into the ECM could be causing the problem, especially seeing as how it has only happened since you installed your superchips tune.

 

Since going to the GMS1 I have never had this happen once since. Prior to the tune this happened frequently in 3rd gear, I know the exact tone the OP is talking about. My other guess falls in line with what 09Cobalt said above, the torque management algorithm may have had a lot to do with this particularly with Learn Down coming into play. Just a thought but I can confidently say I have 0 flat spots with the GMS1, every gear feels the way I'd expect it to .

 

Question, what is the GM Stage 1, would it work with the Superchips tuner, and how much does it cost?

And what is "Learn Down"..... I have heard this mentioned before... something about the cars ECU slowly tuning itself back to stock? I took it for a load of crap.... is there really truth to that, or just "hear say".

 

The GM Stage 1 consists of a MAP sensor, TMAP sensor, pigtails and a tune from GM. If you're curious what it entails check here:

Link to Crate Engine Depot

You can also read-up on it at GM Tuner Source. There's a bunch of articles over there explaining what it is, etc.

Would it work with the Superchips tune, I don't believe so; mind you I have never tried Superchips nor have I read up on it so someone else on here may be able to better answer that question.

Learn Down does exist on the stock tune and it does exactly what you stated. On the stock tune there is a Target HP/TQ and Maximum HP/TQ which both happen to be 260/260. If the tune detects numbers beyond this it will do what is deems necessary to reduce power to meet that the maximum.

The GMS1 flash removes the maximum targeted HP/TQ parameters and ups the target output to 280/320. There are still parameters in place to ensure overboost conditions do not occur, etc. but if you increase flow you should see the benefits of it whereas on the stock tune any increased output would have been negated.

Hope that makes sense I'm trying to type this on a call with a customer so I'm having two conversations at once

 

Yep stock car tries to keep power at 260torque so yes it learns down even when you add mods like exhaust and intake.

 

Stage one is essentially a gm tune, with a couple of extra sensors in it. If you have an aftermarket tune it's not going to be worth it. Learn down basically makes your car always make 260 hp no matter what, aftermarket tunes eliminate this. The GM stage 1 tune keeps it, but up the hp numbers to something I can't remember. I know it's not a lot more.

 

Thought GM has directly answered that learn down was removed in GMS1 but that it was limited only by turbo overspool protection...

 

Yep, I bet if it's not up to at LEAST 185-190 on the temp you might be getting some misfire but not enough to set a CEL.
These engines are pretty picky about being completely warm before wanting to work hard.

 

Thats almost exactly what it feels like... like a 2 cylinder trying to get up and go.... lol! But i didnt get any cels.... and why only in 2nd gear.... well i can feel small remnants of it in 3rd, but 2nd is the killer....... I switched to the Cobalt SS from an 08 Grand Prix GXP (5.3L V8 with the Superchips Tune, was sitting at 325HP at the engine) but it was an automatic and i was just used to slapping it into "D" or Tap shift Manual and going.... This warm up stuff sucks....... But i live in Hot Humid Houston and we only get 4 months of what most of yall would consider "cool" not "cold". My engine is gonna wish it was cold then, lol!

 

That's where a lot of people are getting confused. They think limiting boost means learn down which isn't necessarily the case. Increasing air-flow in and exhaust flow out would not increase boost dramatically if at all and therefore the overboost protection never comes into the equation. That said, the way most people would prefer to increase power output is by increasing boost/air loads (since this yields the simplest and largest gains) in which case the overboost protection is doing exactly what it is intended to do .

 

That's what I thought...

I'm new to the boards, but I've spent a ton of time reading up on all the threads... so please excuse this lurker.

 

What you're experiencing is normal and signs that you're trying to beat on it before it gets too warm. Even during normal driving if you try to beat on it before she warms up (even without no lift shifting), it was cause backfire and blow the spark. These cars don't like to be beat on until normal operating temp and they take forever to get there in the winter (normal operating temp is above 180*).

GMS1 raises the limiter to 6500, 200 rpms above stock. Revving the car beyond that will simply hurt the valve train. I have my limiter set to 7k in first, 6800 in 2nd and 6600 the rest of the way. I only have 7k limiter in first for track purposes since 1st runs out so damn quick.

Don't worry about your flat spots unless if it's happening after the car is warmed up. If it is happening after she's warmed up you might want to pull your plugs and inspect. May be time for new plugs. The plugs when tuned seem to last about 10k at best (all depends on how much timing you're demanding from them, but with the SC tune, it'll be marginally greater than stock).

 

i've learned to let the car warm up... in fact, I won't even begin my commute until its at about 100 degrees... won't go WOT until its over 180

these cars hate some cold weather