blueta

Well I've been having a problem with my POS cobalt lately. When it sits for a while (like 8+ hours) and I get in and drive i've got a HUGE stumble. It starts nicely, can rev it pretty smoothly...but as soon as I put it in 1st and try to pull out it stumbles BADLY and backfires/pops out the exhaust. It's hard to get it up fast enough to 2nd gear. When I shift into 2nd it's the same thing. It'll do this for a couple minutes and then clear up pretty quickly and drive fine for the rest of the trip. Let it sit for a long time and it's the same thing again. A problem with this is I scanned it (no check engine), and no current dtc's (of course with no light), no pending codes or history codes either. It also doesn't do it all the time. It'll do it for a couple days then stop for a couple weeks. Then it's back again for a day or so etc. so it's hard to take it to the dealer for warranty work since I don't know if it'll do it for them. Anyone have any problems like this? It's an 05 w/12300 miles on it and only mods are stage 2 and air box mod.

Area47

check the plugs, change gas stations, run a bottle of heet in the gas tank.

blueta

Forgot to add that I already checked/regapped plugs since the problem. I used different gas stations (including multiple ones from PA and even one in MD when I was on vacation and it still did it). And it's very intermittant and not consistant with anything like weather or such. 3 or so days of doing it and it'll stop for a couple weeks or so. It'll also smoke a LOT when it's doing it. Big puff when first started, then when trying to accellerate it'll look kind of like a smoke screen. Looks like black smoke. I'm completely lost with this.

chevysalesman614

maybe you need to let your car warm up instead of just driving off with coolant temps @ 70*F

Matty

My guess would be a bad injector.

blueta

Yeah, it's carburated too I'm sure no one has this problem with just driving off when not warmed up. It's not like I'm beating on it or anything cold. About the injector, if it was so why would it only do it when cold (as in 8+ hours)?

D4u2s0t

bastard, you beat me to it

it starts ONLY when it's cold, goes away when it warms up, so i would say that's 100% probably the issue.

CTCOBALTSSS

That's the ticket right there. I let my temps get up to at least 100* before I take off and it's still slightly there.

I know what you're saying man. You have to let her warm up.

Matty

Yah I re-read his post and mine did that with the stage 2 tune.

RedlineBrian

What i noticed with my car at least is that these things run like total **** when they are cold. Everyday almost my **** bogs really bad starting in first and in between the 1-2 shift. It sucks, i don't know why it happens, but i just deal with it. Bogs so bad it feels like the car is going to stop dead.

blueta

If we have to warm up these 05+ sophisticated electronic state of the art fuel injection in 85* weather I'll **** myself. That's abusrd. Freaking tbi injected almost dead 300,000 mile junkers don't need to be warmed up. I drove my car immedietly in BELOW freezing temps and it never did it. This just started a couple months ago. I don't know if it ever did it before the stage 2 since I only had it for a couple weeks before that and it didn't act up then. The junker stumbles so badly it feels like it's running on only 2 cylinders. Like a terrible missfire. It's not normal under ANY cicrumstances. GM would never EVER release a car that this would be considered "normal" and just warm it up.

EDIT: So matty and brian both have stage 2 with a similar problem. Anyone else have this problem? Maybe a new tune is in order.

Matty

I have a custom tune. It smoothed everything out. I had stage 2 and when cold mine did what yours is doing.

D4u2s0t

if an engines normal operating temp is around 180 plus, what does it matter that it's 80 degrees outside? just warm the car up for a few seconds. it's not like it takes long

cobaltstg2

mine does it too you got to let it warm up a second ...it has done this since day one

blueta

I don't think you guys are understanding how bad this is. The car barely runs, as in it sputters and almost dies when just pulling out regular. Gm would not ever think of releasing something like that. You would have to be insane to think otherwise. Imagine going to a dealer and saying I'll take the new Z06 and them saying "well son, before you test drive we have to warm it up so it doesn't die when you take it out". AHAHAHA Seriously, that's just crazy. I could let it warm up for about 5 minutes and it'll still do it. It has nothing to do with not warming up the car. It doesn't do it everytime. Didn't do it in the middle of winter with no warm up. In fact in my old owners manual (I think it was for one of my LT1 trans ams) it specifically states that you DON'T have to warm up the car as it's just a waste of fuel economy. Sure if I warm up the car for like 10 minutes it won't do it, but that's not the point. That isn't going to fix a problem, just make it so I don't notice it. I don't like to work that way. Since I make my living off working on cars I do things right when it comes to my ride. And "what does it matter if it's 80* outside..." I almost fell out of my couch laughing at that. This is not supposed to run that way. The standard operating temp is ideal (and below a certain temp our cars won't read knock), but it doesn't mean the car won't operate at other temps. Cars have something called "open loop" and "closed loop". When the car isn't warmed up (to whatever specified temp) it's in open loop. It's basically a non feedback, runs off predetermined specs way of running your car. It's made to run in that mode (doesn't mean FLOOR IT OR BEAT IT). In fact it also goes from closed loop back to open when you floor the car. Does it stall then? No I can't believe people are still saying nothing is wrong with the car. Maybe yours does it too, but that doesn't mean it's not a problem. I guess once (read: IF) I ever figure it out I'll just pm people who are interested in it, and leave everyone else to warm up their brand new cars.

EDIT: I would also like to add to whoever thinks it's normal that this thing smokes something aweful when I start it and it's acting up. I'm talking a huge cloud. 2 reasons it's not normal: No one would buy a new car if it did that as it's a LOT of smoke. I've driven a couple ss/sc's and never had them smoke like that. 2nd is emissions. It would never fly with the government anywhere (especially cali) if it's supposed to do that. It looks like a darn diesel!

Area47

pull your plugs. hell change them for that matter.

what color smoke is it.

ChuckX182

Mine does it too. In the initial 1-2 shift. After that it runs fine. BTW I don't like waiting for my car to warm up even in the winter. My other 2 cars, I never had to let them warm up.

SuperSlow07

if i had to wait to let this car warm up to drive i would set this mother on fire. lol. **** my old dsm's never needed to be warmed up.
pluss these cars hit closed loop in about 30 secs.


so, when it does this is it like a dead miss? there are several things it could be, bad plug (cracked, fouled, etc....) something with the tune (doughtfull because it just started now and you had the tune for a long time) maby a cracked or weak coil, or a dirty or on its way out maf..............


you could always come down to bethlehem this weekend and swap some of my parts to yours and see if it fixes anything??????

bluecobaltss06

I work at a chevy dealership and I have seen this a lot, well in non ss/sc cobalts. There's a "sock" in the gas tank to catch any big debris. Over night it collapses and will cause a problem like that. My cobalt does it also but I think it may be the tune. If you find anything out let me know. It's annoying and I have no time to look at it.

firemanfrank

I've had my car for 2 months and have 1800 miles on it, and it does it briefly.

Happens when I just start her up and then take right off. Right after that initial stumble ...

ALL IS OK!

I don't get a backfire or smoke, but I also let OFF of the gas when that happens.

I imagine trying to gun it at that point would cause it to backfire.

madmark

iTrader: (1)

my guess whould say do the bulliten for the pcm/vcm and update the shiiiii

Sta-meng

i had same problem in my integra. my problem was that i was getting oil in my injectors and it wasnt firing, when i cleaned out the oil i replaced the valve cover seals and it took care of that problem.

also see if u might have jumped timing. it happened in the integra also. i could stay at a light without having to give it gas so it would stay on.

slo_balt

as soon as i got my gm stage 2 put on mine started doing a very similar thing. if i drive before 100degress it would stutter and miss in 1st and 2nd between 1500 and 2000 rpms.
its not the plugs. or it would do it all the time, not just when it warms up.
its the tune. its a safe tune, so its rich.

infernica

I have had the same problem with my car as well, and it still happens with my stage 2. I just ignore it and blame it on a fact of life with this car. :: shrug ::

But I'll be subscribing this thread for future updates! good luck if you do find a way to fix this.

blueta

Interesting about the fuel pum sock. Do you know if there is one that gm uses to replace it with? I would be interested in swapping that out. It shouldn't have jumped timing, unlike your acura it uses a chain, and it's only a startup problem. It runs great after a short time. Valve cover gasket isn't leaking around the plugs either. Plugs are a very nice tan (weird for gm's rich tune haha). I can always just get a new set though since it's easy and cheap. I will also come to b-town and swap out parts 1 at a time and see if we both switch symptoms. It would be nice if you had something besides an 07 so we could swap pcm's! I'll check back if I find anything out.