ok, my car has been running a little lean lately, i had the car tuned back in august of 05 and afr was in the 11's, now it's running in the 12's up to 12.9 afr. I was told by someone that the factory ecu could possibly be throwing it off. I was talking things over with a friend and said that the 02 sensors could be causing this. When the car was tuned back in august i believe the factory o2 sensors were not working and causing a cel. for some weird reason they are working now.

my question is ...

Basically i want to turn off the 02 sensors that go to the factory ECU, there are 4 of them however, and i dont know which ones went back or if all of them went bad. is there a wire on the ecu that i can clip for 02 sensors input or can i clip a wire on the 02 sensors ? someone told me that I can clip the black wire on each 02 sensor and that will cancle the signal going to the ecu ? does this sound like something that would work ?

 

i'm pretty sure the ones in the cats do absolutely nothing at all other than report if the emisisons are bad or not to the ECU. I did the non fouler plug mod which seems to really help some people especially with test pipes

The other ones are in the headers or something right? Maybe in the block even?

clipping the black wires i'm not sure what'll happen. Maybe the ECU will go into limp mode?

 

How long have you been running lean? Did this lean condition start when the temperature dropped? How hot was it in August and what is the temp now?

 

i do have test pipes if that makes a difference,

it was in the 90's when i got the car tuned, the weather now is in the 80's where i live. so weather should not be playing a part with this.

 

colder air is denser so it could cause you to run lean. A 10 degree decrease is not a big enough difference to cause to you to run lean......maybe .1 or .2 if that.

 

they would only make a difference if you installed them after your car had already been tuned. If you had them when the car was tuned you shouldn't be seeing a difference in th a/f ratio.

 

i thinks he means that the test pipe may caused issues with the OS3 sensors not reading correctly.

 

I've never had any problems with my 02 sensors and I have had test pipes since my car had about 2,000 miles.

 

Have you tried to reset the ECU ?

 

yea, im going to do it again and see what happens. i loaded the map back to the ss box a few minutes ago and did a run, seemed to be better down low but high rpm it was still running 12.8 or so.

 

Just a thought....If your running the stock kit fuel system . The FMU may not be building fuel preasure up top .Several guy have reported the washer in the FMU getting sticky and not working right