ok.. i've now gone through multiple o2 censors..

the first one came with the header, and was used.. so i asumed it bad.. replaced it..
the second one i thought, huh.. maybe i got a bad one.. so i replaced it..

the 3rd one still gives me cel code 1.. so it's not the o2 sensor..

however, i do have more info to throw out, so if anyone has any ideas, please PLEASE, share them with me..

1) the cel doesn't come on until i'm downshifting, for a light, or if i'm coming up on a slower car, or something like that..

2) i never did find out if the vac hoses going into the TB are switchable or not.. and if not, which one goes where.. (D15b2 -> D16A6 swap)

3) i'm no expert, but if it's happening during a downshift, doesn't the vac have something to do with the o2 flow ?

ugh, this is driving me nuts..

i've reset the ecu, it still happens, just not as often.. i'm on my 3rd o2 sensor.. but i'm a quick learner, and not afraid to tear it apart..

any ideas welcome..

 

As far as I know, the O2 is either working or it's not.
If it's "lazy" and still working, but not well the ECU still considers it good.

My guess is that your wiring from O2 to ECU is suspect.
Maybe your ECU itself is suspect.

The O2 just sends out a varying voltage to the ECU.
If the ECU sees the O2 reading go out of spec for a while you get a code.

If you have a DVM then maybe you can do the O2 tests the service manual suggests.... just to check the O2 sensor functionality one more time.

 

how does the car actually run? make sure there is a little slack in the wiring for engine movement, etc.. cant hurt.

what is your EXACT setup, ecu? injectors? intake manifold? exhaust manifold/header ?

 

Give your wires a good check or try to find another ecu to plug into it to see if the problem replecates itself. I got rid of my constant #1 when I did my A6 swap by running new shielded wire in the engine bay to the connecter.

 

where is the o2 sensor mounted in the header? if its too far away from the head,
its possible its cooling off enough during cruising to cause an incorrect reading.

It most likely has nothing to do with your vacuum hoses, unless they are swrewed
up to the point of causing an extremely lean or rich condition, which would make
your car run noticibly shitty.

 

don't really wanna bring this back but I don't wanna start another thread... But I just hooked up my 4 wire on my d15b and was wondering does the old wire from the 1 wire mess anything up? like cause it to read wrong. doesn't that still go to the ecu? I just havn't had the time to go in and follow it until I can get it all out.