I have an 06 2.2LT with roughly 70,000 miles on it....here is my issue....for quite some time now I have had this ongoing sporadic rough idle after the car has warmed up....it usually happens when I come to a stop and it last about 5-10 seconds then it smooths back out and my acceleration has gotten almost non-existant unless I step on it and kick it into passing gear....but if I just try to do a smooth acceleration into traffic, the engine sounds and feels like it is smothered.....my gas mileage has dropped tremendously.....now here is what I have done to try to fix the issue.....I replaced the plugs about 30,000 miles ago now, I have had the injectors cleaned, I have had them try to pull codes 3 different times and the thing isn't throwing any code at all....so this last time my mechanic did something with the scanner that showed I guess the actual percentages that things were operating at...and he noticed on my O2 sensors that one of them was reacting as he put a little on the lazy side....I believe it was the back one, but not real sure...anyway...the other one had the numbers changing every 1-2 seconds, but the one that was being lazy would sit unchanged for 30 seconds or more before it would show any change in the number.....he told me to just drive the car until something failed...but that is not my nature...I like to stay ahead of these issues...because usually if you allow something to continue on it will cause other issues to arise....so my question to you guys is this....would this "Lazy" O2 sensor cause the problems that I am having....? I am really just not happy at all with the acceleration issue, even though it is the 2.2...it still should have some pep without having to kick it into passing gear.....

Please...any help/advice would be greatly appreciated at this point....

Thanx...Anita

 

Sounds like you are talking aobut the post cat, the one after the cat. That one only reads the cat. Those usually last, but it could be going bad. Or worse, the cat it self is going bad. I'd have to research, but I think the cat has a 100k mile warranty (emissions)? Don't quote me on that though.

Have you checked the air filter? Check the plugs again in case one went bad?

 

I just talked to another mechanic and he said that on my car the rear O2 sensor isn't suppose to change like the front one does, he said all that one does is read the oxygen blah, blah, blah in the catalytic converter...he said that it sounds like I may have low fuel pressure.....or maybe my converter could be failing.....so I guess I'll take it in to him and see what he comes up with....all I know is the car should have more pep than what it is showing right now.....I might add...if it makes any difference...the car was a rental vehicle before I got it...so it has been subjected to God only knows what kind of driving habits.....

I sure hope that I can get something figured out real soon.....as I am really kind of tired of the acceleration issue that I am having.....I also noticed that it really seems to be worse once the car shifts from second into drive (automatic)...once it hits the drive gear...it really seems to bog down......I know this is supposed to be like an Overdrive gear, but geez.....

Thanx...Anita

 

Sounds to me like your cat is on the way out - clogged...

The rear O2 sensor has nothing to do with engine performance, all it does is monitor the cat - it doesn't affect any engine control parameters.

The front cat should be changing pretty regularly as it is continually sending signals to the engine control computer to adjust the fuel air mix for emissions.

 

try cleaning the intake and throttle body
take off the intake and clean out the opening of the intake and then the whole throat of the throttle body. it gets alot of build up on both and this will really effect the idle