Hi , i will start off by saying i am new , since i just bought my cobalt a week ago.

So here's my mods: gm stage 2 tuned by gm and injen cai , thats it everything else is stock

Here's my problem : while racing with an acura rsx-s in 3rd gear at about 5,5k rpms it felt like if i hitted the rev limiter which i know i didnt cos its at 7k , then for like 5 minutes the car had less power and was stiff. EX : i would floor it at 2k and i would get full boost instantly which is uncommon, and when i release the gas it jerks alot just like if i were in 1st even though im in 5th at 2k rpms , its kinda hard to explain ... Anyways im not a mechanic but could this be misfires in a cylinder or too much gas so it cant ignite. Thanks!

Jeremy

 

Might be clogged cat. Get a downpipe and free some flow up!

 

I would say first off is there a check engine light? Did you notice the check engine light come on while racing? Also if you have a chevy tune for the GM Stage II kit I would assume there might be something off on the tune. Wouldn't be a terrible idea to have someone check it out for you. How much vacuum are you you pulling when you are off the gas coasting down the road? If you don't pull very much then I would say clogged cat. Could be spark blow out from plugs that are gapped to wide or you may try to run cooler plugs. Another thing would possibly be your IC pump stopped working and your IAT2 temps got too high. There's a lot of things that could be going on causing that.

 

Floor at 2k at get full boost+? Sounds like a clogged cat. It won't always set off a CEL, but I'm like 90% sure it's a clogged cat.

 

take it in to any reputable muffler/exhaust shop and have them check it for you. Oh and try not to drive it a lot or put in under a lot of strain. If you do have a clogged cat then you could be putting too much pressure in the cylinders and would do terrible things.

 

First off , Thanks everyone who answered.

Yes i do have a CEL light , my friend thats works at gm did the test for me and it sent a cat malfunction , he checked and it is completely clogged, so he said there is a recall on that should i get a new stock one or choose to go with a downpipe/exhaust system , i think the more air flow the better , what do you guys think about that?

BTW, the new cat + installing is free

 

Depends if you wanna spend money or not. GM covered the cat until 100k miles.
Could just get the stock installed, so you can drive your car, then look into something aftermarket.

 

Yeah ill probably do that since its free so why not, then ill look for something a little better. I just hope that was the problem and nothing else is wrong...

 

Changed the cat , problem still not solved does anyone have an idea ? :s

 

I bet your high boost problem is solved. Sounds like spark blow out around 5.5k. Check your spark plugs.

 

Don't floor ur car at 2k in fifth

 

Yup boost is back to normal but power loss is severe right now and the car feels like if its missing gas or fire. This is what i tried so far : new cat , new maf sensor , new cam positioning sensors. Im tired of putting money on the car since i just bought it ! Damn

 

And i forgot to say that most of the time the car is fine but once it egts the first power loss around 120kmh(70mph approx) it stays like that until i shut it off wait 5 sec then restart the car , if i do that hes fine again , so weird

 

Sounds like a bad fuel injector

 

should i try cleaning my injectors?

 

Bump.
Does anyone have an idea im really out of ideas

 

Second this, check your plugs for the correct gap (search on here someone has most likely posted the correct gap for GM st2) or replace and gap them.

 

Ok, so i checked my injectors they are good , checked my spark plugs they are good , not burned or oily and the gap is 0.035, tomorow i will check the fuel filter. Oh and i forgot to say that when the tanks gets lower to 1/4 the power loss seems to happen more frequently and after 1/8 its all the time, just saying maybe it has something to do with the problem ?...

 

Bump, i cant believe this never happened to someone on here, if anyone has an idea, please reply or pm me !

 

Found out the problem, After wasting 3500$$ in repairs and work, we finally found the only problem my car has is the engine is going bad. 70/100 blowby , 50PSI on 1 and 3, 125 PSI on 4 and 2 seems normal.. Anyways the oil is pouring out of the dipstick. If anyone has an idea where to get a good engine with 100k km/60k miles or less , Please PM me. By the way i live in new-brunswick canada, so id prefer to get an engine from canada..

Thanks,

 

How did you spend 3500 to change spark plugs, fuel filter, air filter, and a compression or leak down test?

 

damn, you blew the motor in 1 week of owning it?

 

No actually i changed : Spark plugs, fuel filter, air filter, compression leak test, MAF, Cat, Many sensors including O2, Crank position and a few other sensors plus GM did a good 10 hours on it so yea roughly 3500$$

 

No, when i bought the car the guy said it was the MAF, the car had a wierd idle so it could be a maf ... turned out it was not the maf at all , and i did nothing wrong with the car, really .. He knew the engine was totalled when he sold it, bad trade for me

 

Check with Mongo he has one for 600+ shipping I believe, if you're in canada and can make the trip to Pittsburgh PA I'd say drive there and pick it up with a friend because shipping would be crazy.