Just put on the 2.4l intake manifold on my 2.2 but ran into a little problem. Drives good and feels quicker but it idles in between 1500 and 2000 RPMs. Theres no cracks or leaks anywhere and i cleaned the throttle body. Does anyone know what the problem could be?

 

Unplug battery for about ten mins.

Before you do, do you have any trouble codes?

 

DId u put that little green metal plate into the mani? They say if you dont put that in idle is retarded.

 

I unhooked the negative terminal to the battery before I installed the manifold and I made sure all the gaskets were in tight even that little green center one. No CEL or nothing just idles like a bitch lol. Will a tune solve this problem?

 

i heard that for some reason the 2.4L intake doesn't work as well with the '05-'06 Cobalts as it does with the '07's, but don't hold me to that

 

Thats true because the '07s have the same exhaust manifold as the SS/SC/NA which flows much higher than the 05 - 06 manifold.

So there's a good chance it might be a restriction. OR you just didn't install it correctly...?

I'm not sure but when I installed mine I never had any trouble at all. No codes or anything.

 

No problems here either. I did it without instructions

 

check all of your lines that you reconnected. thats way to high. mine sits around 750 or so with the 2.4 manifold on.

did you clean the engine at all when you had the manifold off ?

 

Sounds like a vacuum leak somewhere between the TB and the engine.

 

I have a full exhaust so i dont see how flow would be an issue?

 

def leakin somewhere..which will cause a rough idle..u def want that down...re check the gaskets..have someone rev ur car up around 3000rpm and hold it steddy for a min...u shud hear a leak, if there is one

 

Agreed.

My 92 Mercury Topaz used to idle at 3000 because of a massive Vacuum Leak.

Here is ONE way of checking for a Vacuum Leak.
https://www.cobaltss.net/forums/show...highlight=Leak

 

Air leak

 

I have an 05 and no problems. I have no clue what it could be other than an air leak. check your intake, all the way.

 

Its the break boost line. Did you install the new one properly and hook it up to the new manifold?

 

I did everything that all you guys said and still idles like a bitch. No leaks at all and i hooked the brake booster up correctly too. idk man

 

i believe theres only 2 vacuum lines you mess with on the intake manifold. i cant remember exactly since its been a year since i replaced mine. check to make sure the clip on the break boost line is all the way on, i know i had that same issue when i blew my intake manifold to peices and my idle was sitting around 2k rpms. i even blew apart the clip on the boost line itself and when i drove and hit boost it would force out the break boost line and id have a crappy idle again. I would look it over just once more, its got to be related to that somehow.

Doesnt the 2.4 intake kit come with a new break boost line to extend it?

 

it does and i have the line clamped down real good where it connects to the manifold, idk maybe i just need to get tuned. That should solve it right?

 

You have a vacuum leak....that's the only reason that you are experiencing problems....

take that adapter plate off the TB and install (if you can) the TB straight to the manifold (make sure the seal is in place, the little green one) and give that a shot....

if it's not that, then take the mani off and check the seals again....especially the PCV seal (the one in the middle)....give everything a good wipe down even the head but be careful not to get crap in there...

reinstall and give it a try....and check your MAP sensor seal too....that is a biggie....

 

If I take the adapter plate off the throttle body, the manifold opening sticks out further than the throttle body. Then we got a huge leak lol

 

hmm....i have the adapter plate but didn't install it on mine....so there is a difference between the TB in 07 and 05....then what i suggest then is check that MAP sensor seal....and make sure that everything is snug and sealed.....have somebody there run the RPM up and you listen for the hiss and see if you hear it....i had the same problem...mine ran idle at 3 grand...and turned out to be the PCV and the MAP seals....

 

alright ill try that...Thanks man

 

If the obvious things, TB seal, MAF seal, brake vacuum line, etc., aren't the problem then you will need to take the intake manifold off and insure you got the 4 mani-to-head seals and the PCV plate installed -- is it possible one got misaligned or pinched when you installed the mani?

Do you have the gasket between the TB and plate?

 

everything is connected the right way and gaskets are all on correctly and snug. Im leaving the battery disconnected for the night and seeing how it goes tomorow. Hopefully everything will reset to normal....I Hope!

 

We had a discussion on this site (can't remember the thread now) about disconnecting the battery Vs Clearing the ECU with a scan tool. According to a Technician the ECU has an internal battery which doesn't allow disconnecting the battery to clear everything out. It would be better to get a scan tool that can erase codes. According to the factory service manual erasing/clearing codes resets all the learned functions (MAF, 02 sensors, etc).