Hey everyone. I'm troubleshooting my sister 06 cobalt ss for her since she doesn't know much about cars.

ISSUES WITH THE CAR
idle bounces (sometimes to the point that it dies)
only boosting 4psi then dropping off down to 2psi into higher rpms

Now, she has an Injen intake on it and I read that Injens are notorious for making the idle bounce. Can anyone confirm for me? Oh also, I did clean out the throttle body. It was pretty dirty.

I swapped out the boost bypass actuator and no change to the boost. Then I took a closer look at things and noticed a 2.6 pulley. Smells like its running a bit rich as well. My sister said she has really bad gas mileage. No clue on what injectors are in the car. Didn't have time to check.

What do you suggest I do about this situation? I was thinking about the stage 2 kit so I know for a fact that the pulley, injectors, and pcm are all what they are supposed to be and also change out the intake.

Thank you for any help.

 

The idle bouncing is a pretty common problem with 60# injectors, which I am assuming are in the car if it is running a 2.6 pulley.

As far as boost, you should be seeing more than 4 psi; alot more. It maybe possible that the guage itself is bad. When you get on the car hard does it feel like it is pulling really hard?

 

I was going to suggest cleant the tb.. other than that idk.. is the car throwing any codes? if so what are they?

 

running a 2.6 without any cooling mods?

 

Low boost and the car dieing at idle could be because of a vacuum leak.

 

No, definitely not. I'd believe it when it shows only 4 psi because it definitely doesn't pull like it should.

Yes it is but I couldn't find my scanner to check it. Will do in a day or two.

I'm still learning about the car. All of these mods were on the car when she bought it. When I saw the 2.6 pulley, I was like WTF?

I'm going to check the lines again to make sure they're all good.

 

Sounds like you might just need a tune:
I baught mine used. Had a 2.85" Pulley, with 40# injectors.

GM did a stock flash to the INTENSE (Another mode, its on the drivers side in front of the fuse box/ check to see if it has something like OTTP or INTENSE or ZZP or something)
So when I got my car used, then I gota engine light and it ran rich/crappy too.

 

Injen intakes do not cause rough idle. I dont know where you heard that from. Check the MAF sensor. It could be dirty, and would also cause idle bounce. Also, like one member mentioned 60 lb/hr injectors are know for a slightly "rough" idle.

 

with a MAF there really is no inbetween, either its good or bad. and plus it would put it into limp mode if it was bad.

a 2.6 is wayyy too small for a unmod'd/untuned car. my guess would be belt slip.. massive belt slip lol

 

there is an in between with maf's unfortunately, my car for example threw 3 codes for 4 months, system too rich, fuel air metering system and supercharger bypass codes, CEL would come on for a couple days then go off, and go back on at idle mainly.

Changed the maf and all 3 of the codes are gone and hasn't come back now for 6 weeks/3k miles.

For good measure I also cleaned out the throttle body about 2 weeks after the maf was replaced.

 

My advice is find somebody local to u that knows about lsj's and have them check it out and tel u what u got , or take a pic of whats under ur hood and post it on here to see what kinda injectors u got...as far as the tune goes u would need a tuner to check it out for you...and with the 2.6 " pulley i hope you have some serious cooling/exhaust mods on the car or else u might have more problems than now...

 

is it on stock exhaust?

 

there is an in between.

i agree that a bad maf sensor will put you in limp mode, but a slightly dirty one can cause idle issues.

 

2.6" should be pushing 20psi
lol

 

Yeah, if you're on the stock exhaust ....

 

2.6 def needs meth or e or both to combat heat, poor m62 that could

 

It doesn't sound stock. I'm gonna have to take a look underneath to see whats going on with the exhaust.