q about o2 circuits and CEL's.

[D347643]

I had another thread on this... but im getting crazy readings from my o2's. My right one starts out at about .2 and then after a few minutes of the car running goes to .00 and will rise to .08 if i rev it up. the left o2 stays about .2 all the time and constantly says lean for both on my PMS display. My A/f is out of whack, way too lean. (all of this happened before my PMS btw) anyway my q is why isnt my CEL coming on sensing that my o2's are reading very lean? If my ground for HEGO's wasnt hooked up would it not throw a code? My CEL never comes on unless my car dies or im checking codes. Hell I got a codes 63,71,72,74,75 after I cleared the comp's memory and the CEL still didnt come on.

thanks

Drew

 

[D347643]

oh and I have longtubes headers, ive heard since the o2's are farther back they arent heated up as much. Another thing, under WOT my a/f is great, which would point in the direction of a 02's sensor fault.

 

[D347643]

bump

 

[jrichker]

The long tubes definitely have an effect on the O2 sensors. They will be less accurate since they are not as hot as they should be.

Check the Orange wire in the fuel injection harness, it is the O2 sensor heater ground. If it doesn't work, the O2 sensors do strange things.

 

[D347643]

ok ill check that ground out, but is it normal for my comp not to throw codes for low o2 voltage? even, for example, if the ground wasnt hooked up?

Drew

 

[D347643]

bump

 

[D347643]

ok well despite me getting low o2 voltage why isnt my comp throwing an o2 code?
i checked the orange wire and its grounded out perfectly. resistance from the pin 49 to body ground is 0.0

 

[D347643]

come on, anyone?