So O2 sensors seem to be it? No other possibilities?

 

no one is going to pin point what the specific problem is.. you can either keep swapping sensors till you find the problem.. or you can bring the car back to where you had the work done for them to look it over.. the choice is yours.. but we can play this roulette game all day long

 

True, but money is not allowing that right now... So I am trying to fix it myself.

So the upstream O2 sensors (on the manifold) are the only ones that adjust themselves? Can the rear (downstream, on my test pipes) O2 sensors do the same as well?

 

no.. they just tell the ECU if you have cats there or not.. they don't do any adjustment at all..

but now that i think about it.. the front O2's are only suppose to start reading after the car is warm.. so the car wouldn't be reading rich when cold

 

It only read rich the one morning I went to work. Besides that, everytime after driving it within 15-20 min it would starting reading rich.

Any other thoughts?

 

so when you start it up cold.. what does the A/F read? if its ok... then once the car is warm it goes to 10.. that would indicate the Front 02 Sensors

 

Yes, besides that one morning, its always been after driving it within 15-20 min. And when it is already warm, lets say I drove it for a bit already, and I get back into the car within an hour or so, it starts off rich again

Well, now I gotta save for some expensive sensors. LOL!

 

what about the OP? doesn't he have a Z? maybe you can swap his sensors just to make sure thats the problem before you waste money chasing problems you don't have

 

So problem was sensor? Or what

 

Not sure yet, but we are gonna try putting in some different sensors, and hopefully that does the trick. I hope it works...

I would just imagine, the Check Engine Light would come on, telling me they are bad? Right? Or maybe thats not it? I am gonna shoot for it anyway...

 

He has an HR, so it wouldnt work. I will ask a couple other buddies I know...

 

since the ECU is controlling the car.. its definately a sensor.. i guess the ECU doesn't see it as a real fault to trigger the CEL as yet

 

Sounds good, I am gonna try it tomorrow...

 

One more quick question... Does it really take the sensors that long to heat up? About 15-20 min? Any, I actually drove it all day yesterday and did it once all day. Which is weird as well.

 

change plugs (sorry if you already tried this), but misfires will cause you to run rich, because well, the fuel doesn't burn. It's either that, O2 sensor (but both banks rich?), the UTEC (i've had it hold injectors on one bank wide open!), or the injectors.

 

Thanks. That is exactly what mine is doing. Runs great at WOT, bad at idle every other minute.
I used to have the m/s misfire when I had the NGK coppers, switch back to Iridium & no codes now
It only happens when my motor is warm...
Totally sounds like the o2 sensors. I have a spare set, just not enough time to install.

 

Well, plugs are only a month old, injectors probably like 2 months old, lol, but Utec is a couple years old (like 5 maybe) I will try the O2 sensors, and see what happens.... which I rather have them be the problem, instead of Utec.

 

Oops - sorry I missed that part. What kind of plugs did you replace with? Could still be the cause... That you noticed the P0300 right when it runs rich is a good clue.

 

I think that code was just a coincidence that one day. cause it has not come back and it still runs rich. I have one step colder plugs, NGK.

 

Why not check with where you got tune? Isn't that much easier? I'm sure shop will not charge you if you come back to check your A/F issue.