I have 3 heated o2s.

none of them seem to work right

at first when the car went into closed loop the INT would start going down and it would stall. I would start the car up again and it would stall within a few seconds, and keep doing that. this was consistent with 2 heated o2s

I put my 1wire o2 back in, and the car ran normal again. BLM and INT stayed at 128 once in closed loop.

so, I got another heated 02 and now the o2 cross counts go up from 0-255 quick like normal, but the car will not go into closed loop?

what gives?

 

New or used?.
Bosch?.

Does the O2 drop out when hot?.
If you don't need a heated O2, then there's no need to run one.

If the O2 does drop out when hot (ie due to cold ambient temps), then you might have to lessen the decay rate of the choke settings so the choke functions stay *on* longer.

 

2 are DENSO, 1 is ACDELCO. all are used

I live in Wisconsin, so it would be nice to have it for the winter

what exactly do you mean by 'does it drop out?'

 

It's possible then that all 3 are bad, all it takes is the faintest wiff of silicone to kill one.

Ya, if it's needed. Like I said if it's not needed, and your having a problem when you install if, then leave it off.

*drop out*, is having the cross counts drop to 0, with a warm engine. It *can* happen with headers, allowing the sensor to cool off too much in cold weather. *can*, doesn't mean it's going to happen on all cars.

The trick with cars, is being sophisticated enough to get the job done well enough. Once you get to being *trick* for the sake of being *trick* you can run into problems.

 

It is a bosch, but its cheap and i've had good luck

look for a sensor for a 1993 chevy astro van. 3 wire heated, about $30.00 new.

 

I had the heater ground and sensor ground going to the same spot. today I grounded them seperate

the o2 cross counts were going up right away, then they stopped climbing after about 3 minutes. it didnt go into closed loop either

I might just say screw this whole idea because its just taking way too long for something that should be simple

 

Sensor ground on a 3 wire is the sensor case, no wire. If 4 wire, depends on on the type - some are case and wire ground, some are isolated wire ground.

If the exhaust is not WELLLLLL grounded, and you run the heater current through the exhuast (don't think you have it this way), OR if you're using a 4 wire, with the sensor ground being further outside of a high current connection to ground, it might raise the volt (potential) of the sensor ground, thus showing high volts on the sensor (since it's now no longer at 0V ground).

 

I think im going to try a denso 3 wire # 234-3094 sensor

hopefully this isnt a stupid idea but im not having any luck with my 4wire ones

awhile back I had a innovate motorsports LC-1 wideband and had trouble with it also. they sent me a replacement and I could never get the thing to work

seems like these problems might be related, although ive tested the switched 12v wire and it works fine, on the ground I drilled a hole scraped the paint around it. ground has continuity all the way to the battery, and the ECM o2 sensor wire is fine because it works with my 1wire

 

If this is on a 7730 ECM, be sure that E15 is grounded.
It is the o2 low path IIRC.

 

yes, it has a 7730. does that E15 matter if its a 4wire, 3wire, or both?

thanks

 

Would be for both.
E15 is the opposite side of the input and used as the ground reference for the actual o2 sensor input value.
Probably because it is a low voltage signal and noise immunity.
Not an EE, just my thinking and I had problems with my install until I did that.
I did mine from scratch, The ground might already exist in your harness just figured you should check it if your having that many problems with o2s.
I grounded the o2 heater on the 3 wire and on my LC-1 to the same ground point and do not have any issues.

 

I'm thinking I might have the wires mixed up. heres how I had it:

BLACK-ground
BLACK-ground
WHITE-switched 12v
PURPLE-ecm

I was told the 2 black wires are for the heater, and I should of had one going to 12v and the other ground. and the white wire was the sensor ground.

im gonna try that tomorrow, hopefully I didnt fry all 3 sensors!

 

yeah, I think you're right. Typically I've seen 2 same color wires are for heater (white or black), and purple (with black heater wires) or black (with white heater wires, and gray sensor ground) as sensor output. That leaves your extra white one as ground.

You can find which ones are the heater with an Ohm meter. Should be about 6-10 Ohms, ish, depending on the heater power rating. The sensor and it's ground would be high impedance (reads as open), so don't bother trying to find out which it is. The sensor ground MAY be case grounded also, but it would've blown your fuse if you wired it to 12V, so yours shouldn't be case ground.

 

3 wire Delco AFS-74
A = heater power WHITE
B = heater ground WHITE
C = sensor output BLACK

4 wire Delco AFS-75
A = o2 low TAN (E15 connection, then also to ground ??)
B = o2 sensor output PURPLE
C = heater ground BLACK
D = heater power PINK

Colors may be different depending on the pigtail, etc.

 

the problem was the wiring. I got a brand new denso 3 wire and everythings ok now

the car went into closed loop in 2mins and all is good

on heated o2's there is 2black wires (or which ever wires are 2 of the same color) and one of those goes to 12v, the other ground. you can even switch them around

before I had both black wires going to ground, the purple to ecm and the white wire to switched 12v

very confusing how they made the wires but oh well I know now