Problem: Rough idle (Car sounds like a ******* WRX); Lack of power.

Things I've replaced/checked:

Brand new spark plugs with correct gap.
Brand new fuel filter.
Clean air filter.
Clean MAF.
Clean TB.
Switched gasoline.
Ran Seafoam through the brake booster line and gas tank.
Changed oil.
Checked for exhaust leaks.
Checked for vacuum leaks.
No CEL.

I'm at a loss here..

 

Not sure with the electronic TBs as I have not tried this, but I would turn the key forward just to get the power on, then look in the TB as someone else presses on the gas.

Not sure if the motor has to be on to actuate it.

Look to see if making a few mash the gas moments shakes whatever loose so it sets back to it settling point.

I would get carb/ TB spray and clean the heck out of it.

Don't be surprised when the car has a hard time starting and is rough running for 3 seconds.

Just noticed you have the 2.4 manifold.
I wonder if some burr of gasket material is blocking the throttle plate.
I could be wrong, but its something I would look for.

 

Actually my 2.4 intake mani is not installed on the car at the moment, as I was waiting to get this problem resolved first. I have cleaned my TB before and I moved the butterfly with my hand and maybe I fucked up the idle point?

 

At rest it should sit alittle open due to the springs.
When you turn the key to start it should close tight to learn the position.

Throttle Body Assembly
The throttle assembly contains the following components:

• The throttle blade

• The throttle actuator motor

• The throttle position (TP) sensor 1 and 2

The throttle body functions similar to a conventional throttle body with the following exceptions:

• An electric motor opens and closes the throttle valve.

• The throttle blade is spring loaded in both directions and the default position is slightly open.
• There are 2 individual TP sensors within the throttle body assembly.

The TP sensors are used to determine the throttle plate angle. The TP sensors provide the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened.

 

Drive-by-wire TB blades don't sit flush...the throttle blade is used to control idle unlike a cabled TB that has an IAC valve to do this.

 

Thanks for the information guys! I have cleaned my TB and **** and my car still idles like dick. Dealership says nothings wrong, but it sounds like it's having a hard time just idiling..

 

hey i am asking around what is the best cobalt to buy the sc or the tc i wanna no what to buy?/

 

 

Bump! Cleaned the TB completely, cleaned my air filter and made sure everything is tight, no loose hose clamps, etc. Let the PCM relearn parameters.

Car still idles like complete ****! No CEL.

 

Bump.

 

dirty MAF sensor maybe?..... sounds like you're narrowing it down now

next thing I'd suggest is pulling and checking your plugs

 

I cleaned it with MAF sensor cleaner so it's perfectly clean, and wouldn't plugs throw a misfire code..? Because that's what the dealership told me when I brought it in.

 

hadn't heard of that...maybe if one broke apart or something, but not if it's simply fouled or the gap on one has either collapsed/expanded, which can happen from time to time especially on #1 or 4 I can't remember.

It's a 15 minute job to pull and inspect them, so just figured it'd be something easy for you to check.

 

Alright, I'll be checking them today. How do I know if it's fouled?.. and what should the gap be on a 2008 2.2L? Isn't it like .043?

Here is one of my plugs, they all look like this. Nothing seems to look wrong with them..

 

no, those look perfect.... I don't know much else to look for now

 

Well, I guess I'm stuck with a fucked car.. Ugh.

I have no clue what else it could be.

 

could be a coil pack, but I think that would really throw a CEL, but not sure... and I wouldn't know how to test it

hmmmmmm..... I know the 2.0 doesn't have a traditional PCV system = no PCV valve, does the 2.2?

 

No sir, it doesn't.

 

I would suggest maybe a semi-clogged cat or bad O2 sensor, but your spark plugs looked almost new so I doubt either of those would be an issue.

I'm fresh out of ideas.

 

Wouldn't an O2 sensor throw a code too?.. And how would I check for a clogged cat?

 

Bump.

 

More than likely it would, but they can degrade enough to cause problems before they're so far gone to throw a code.... but like I said I don't think it's likely either of these is the issue, these are usually high-mileage problems.

Hopefully someone else will chime in with an idea. BUMP!

 

its your cat man and you cant really tell unless your loosing power which you are.

 

Bump.

 

Pull your valve cover off and check your rocker arms. See if any are missing. I know a guy that was having the same problem in his sc rough idle loss of power and in the case of the supercharger overboosting just an idea. I am having problems of my own in this area but still trying to figure it out