Ok, so I've gotten code 52 several times on my Boostbutton Cal'd SBEC in my 2.5 mitsu turbo, intercooled Dakota.
New 3wire O2 (NTK) now has 6k miles on it.
Is there a reading I can take with a DVOM to figure if it's a sensor failure? or do I need a wide-band scanner?
Resetting the SBEC and it runs great for a month or so till the 52 is triggered again.
Only 3-wire? Where does the ground go to? Battery or chassis? My guess is that's the problem. The SBEC usually has a 4-wire O2 with a dedicated signal ground. It's more stable than the chassis ground. If you're using a chassis ground for the O2 signal, then any change in the ground circuit or even just electrical noise shift will throw off the O2 signal.Originally Posted by gears351
So I should run the ground to the battery rather than the block/intake manifold like it is now?
I've got a 3 wire as that's what the 1989 harness I used had.
Or should I swap in a 4 wire plug and run the extra ground to the battery?
I'd use a 4-wire and run the signal ground back to the computer (there should be 1 or maybe even 2 'sensor' ground wires going into the 60-way on the SMEC).
I think I left one of those grounds through the SMEC open. Any sources for a harness for a 4 wire O2 and new O2.
I'd rather make the one I've got now work - that being the case should I switch the ground from the block to the 60pin? Does it matter which ground pin I use on the 60? (I don't mean randomly connecting it to an open receptacle) IIRC there's a green signal to SMEC, White/bk power hot key on (off J2) and the Black ground. Could I just re-route the black ground to the appropriate pin of the connector at the SMEC?
On the 4-wire O2:
1 white wire should go to 12v (stock, this goes to the ASD relay and is the same 12v that supplies the coil, injectors, and fuel pump)
White wire #2 should go to battery/chassis ground
The white wires are for the heater only, and do not affect the signal directly. It doesn't matter which white wires to 12v or ground. It will still heat up the same.
The black wire on the O2 is connected to the black/dark green wire on the harness and goes to pin 23 on the SMEC 60-way. This is the O2 signal wire.
The gray wire on the O2 is connected to the black/light blue wire on the harness and goes back to pin 4 on the SMEC 60-way. This is the sensor ground.
Do not connect the white heater ground to the ECU. That will cause problems.
The issue here is that you have the sensor ground tied together with the heater ground. Since the heater supply also has the fuel pump, coil and injectors on it, there's a lot of inductive noise on the 12v side; which can and will affect the ground for the sensor (it's only a 0-1v signal, so small changes for the pump or coil have a big impact on the O2 signal).
Yeah, just got done looking at my wiring diagram. #15 & 16 show LightBlue/Red Sensor Ground and #23 is Black/DkGreen O2 sensor. I've got it hooked up with #23 to the O2, White to J2 power (ASD) and Bk/Wt to ground at the intake manifold.
Only fix is convert to 4 wire? Can I pick up a weatherpak connector and a specific NTK O2 sensor for a 1990 Daytona?
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