My check engine light came on so I took it to autozone and their scanner said front bank o2 was lean and CPS was malfunctioning. It's obviously in open loop mode with the CEL on from the o2, so I assume it retards timing a good bit and richens it. So onto the questions...

1) What brand(s) are recommended for O2 sensors?
2) I'm going to replace both O2's, but which sensor is "front" bank?
2) Could running in open loop cause the CPS code to come up, or does this have to be a bad sensor??

I am going to order a timing chain kit from RockAuto so I was going to get the other parts from them to save on shipping. They carry AC, standard, NTK, Bosch, Delphi etc. I'm leaning towards AC delco because the oem lasted 140k. My b-day is tomorrow so I really have to get this fixed asap so I can get it inspected at e-Check before Ohio lets me renew my plates. If you don't have emissions testing where you live YOU ARE LUCKY!


EDIT: See below for updates

 

Get ac delco o2 sensors and cloyes timing chain kit

 

For anyone else reading this, just saw the Cloyes timing kit is on wholesale for $65 instead of $114 right now, so if you need one ya better get in on that before they sell out. And thanks for the reply.

 

you had better check out and see if your sensor is bad before go tearing into the engine

 

This is why I'm asking if the open loop mode and o2 sensor codes can cause the CPS code. My other though was the tensioner is obviously bad because it rattles like a diesel, so maybe that is the culprit.

 

no it wont

 

Would a faulty tensioner cause it though? Because the cams are directly related to the position and tension on the chain. Either way I'm going to buy the CPS and Cam sensor because they are less than $25 combined, I'm no paying S/H again just for $20 in parts.

 

is the valve train making a bunch of noise

 

Buy revised chain tensioner, install and see if that's the culprit. With that many miles the chain is most likely stretched but a new revised(lnf) tensioner will fix some slop. If issue still occurs I'd say bad sensor or timing set

 

mrbelvedere, it's impossible to tell of the valves are making noise because it's coming from all over. I assumed it was the M62 coupler but after I replaced that the rattling sound was still there. I've heard other people's worn out tensioner video clips and it's exactly how mine sounds. Last winter it started that noise but it would go away within 30-40 seconds of idling. But this winter it makes the noise a lot longer.

So if the tensioner is at fault, the chain has likely stretched more by now. If it did stretch at all, that would have to make the CPS read wrong. Even a hundredth of an inch will change timing. I could try doing just the tensioner first, but GM recommends replacing the chain at 100-125k so it's definitely due.

 

do the tensioner first

 

Do tensioner first and please use acdelco parts

 

I have to revive my thread, since my results came in...

I reset the ECU and replaced the front o2 on the manifold and went for a drive. The CEL came back on after 20 minutes, but now it just has P0171 for the front o2 AGAIN. The only thing I've done to the car lately is the airbox mod with a cone filter last month. I did have the eaton off to replace the coupler and put in new oil, but if the SC gasket was leaking air it would run like total crap. It actually runs perfectly fine but feels a tad sluggish and gets less mpg. Would a MAF issue cause the front o2 code? I guess I could try to clean it. Any ideas or suggestions?

 

Check your intake manifold hoses very closely i had the same P0171 code when i got my car from the shop, car idled like a subaru, turns out they ran the hose from the back of the evap back to the front of it which left the front opening on the engines manifold (which is supposed to go to the back of the solenoid) open, plugged them in the right spot, reset the code and bam problem solved, ...now if i could get rid of this P0300 and high rpm misfire thing id be fine but yea look over your lines closely, might find something


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i would do a boost leak test and see if you have a vaccum leak