Hey guys,

So, got the car back from the dealer today. Got it inspected, but still having the two CEL's from before. I swapped out the front 02 yesterday, but that didn't fix it. Supposedly the rear 02 has some bad wiring from when I was installing my header/dp and the wiring is causing shorts. But aside from that, it seems to have a lean idle issue from the codes. The one code it gave me shows no readout though, but I have the common P0171 code (fuel trim system lean ecm/pcm). My current set-up is an Injen CAI, K&N cone filter, DIY air induction in the wheel-well, and GMPP Performance catback. Stock header/dp currently. Not tuned. It has a new front 02 sensor, and apparently a bad rear 02. The MAF was cleaned about a month ago, the air filter is a little older, but still clean. Shouldn't be an oil issue. New Delco Iridum plugs. Any other ideas? I heard something about an EVAP canister or something? Fuel filter? Anything? I'm really not sure and I don't want to just randomly start replacing stuff. Should I pick up a new rear 02 sensor or just get HPT and do the "rear 02 delete"? I always use 93 and sometimes run cleaners. Any ideas? Anything at all? The car runs well, has no vacuum leaks, and still gets good gas mileage. The only issue is that every once in a while while at idle, the car will bog down for a second or two, then be fine. Aside from that, in overdrive on the highway, the car seems to drag on a bit when I back off the gas a little more than it used to. No clue.. Any help would kick ass..

Thanks!!

 

I would get a new rear o2 sensor, IF YOU THINK ITS BAD. It sounds to me like you do have a bad fuel filter.

Heres what I would do:

1. Change fuel filter
2. Get new rear o2
3. Check plugs

 

I would replace both O2 sensors. Had a similar prob with a 2.2 cobalt at work. Rear O2 caused most the probs. Was being lazy and woulnd't change voltage at all. Changed both to not have a come back

If you have some way of reading the voltage in the rear O2 i'd start there

 

If I do the rear 02 delete through HPT would that work too? I already did the front 02 a few days ago, and the plugs are almost brand new..

Where is the fuel filter in these things and how hard is it to fix??

 

Don't know for sure. I also did the rear O2 delete on my 2.4, but the wires got messed up and it threw the CEL. So It still may effect the comp.

The fuel filter is just above the rear axle near the evap canister. The fuel line clips are a lil tricky. There's a "HOW TO"

 

So you'd still replace the rear 02? If I replace it, I'm not gonna do the rear 02 delete.. I'm still catted anyway. No real use in getting it removed.

 

Yeah I'd still replace the rear O2. It's hard to tell without voltage readings to be sure, but if you can try and scan them. I would just leave the cat on. Car sounds better with one on and a high flow cat doesn't rob alot of power at all.

I'd still replace the fuel filter as well. Should be changed every 15k to help things.

 

I'm gonna pick up a fuel filter tomorrow, as well as a cabin air filter. haha

I will likely just replace the rear 02, but I don't know if it'll be sooner than later.

But yes, there will be a cat on this car regardless. When I had the ZZP combo on it, it was originally catless. Sounded like complete ass. Never again. lol