Crazy WBO2 Install Behaviors - Please Help

[flightlead404]

Before I lose my mind completely!

After a run of bad computers and bad sensors, that may have masked this issue or this issue may have lead me to believe sensors and computers were bad that weren't I FINALLY have this behavior nailed down and it is a head scratcher.

I have a known and verified good controller (ALM-INLINE) and known good, and tested Bosch LS4.9. Both of these devices are good, and work together......most of the time.

When I say they work correctly, I see the linear output voltage from the controller behave as expected.

Whether running on ships power or on an isolated power supply the behavior is the same. When I power on the controller/sensor I get a 20 second delay at around 0v output (normal voltage) then:

-In free air it goes to 5v - normal for this controller
-If I use an unlit propane torch to pass gas () over the sensor the voltage drops as expected
-Remove the gas, voltage rises again
-If I'm on ships power whether the engine is running (13.7v input) or just jumper power (12v input) behavior is the same
-If I hang the sensor in the exhaust stream from the exhaust tips or from the gas stream from the empty bung hole () same thing, voltage drops, pull it away voltage goes back to 5v

All this is normal behavior.

BUT as soon as I screw the sensor into the bung the voltage remains at 5v and doesn't drop when the engine is running.

The ONLY difference is the sensor is screwed in to the bung. No other differences in power, grounding, where or how I'm measuring voltage......nothing. As I mentioned above, I can even dangle the sensor NEAR the bung and see voltage changes in the exhaust stream.

I've even tried grounding the sensor body while out of the car to see if it was something electrical, nope it works fine.

Why would a wideband O2 not output a correct voltage on the linear output when screwed into the exhaust, but when unscrewed works fine?

Its a RarlyL8 exhaust and a year ago I didn't have this problem. And again, as I mentioned above, there's PLENTY of exhaust coming out of the bung hole () when the sensor is not screwed in.

I can't figure it out!

[Alan L]

I had an issue installing mine. NGK, with same Bosch sensor. Contacted the supplier who told me I had not earthed it properly - of course I disagreed. But it turned out he was right.
Regards
Alan

[flightlead404]

Originally Posted by Alan L

I had an issue installing mine. NGK, with same Bosch sensor. Contacted the supplier who told me I had not earthed it properly - of course I disagreed. But it turned out he was right.
Regards
Alan

Alan

Can you clarify please? Do you mean there was a potential difference between where you earthed controller and the exhaust?

Was your issue the same behavior as mine?

[dap930]

That sensor behavior is hard to explain. It is almost like there is no exhaust flow going into the sensor when installed. I am using ALM-ADV which works great on my install. I also have an Innovate sensor heat sink installed, which spaces the sensor further away from the exhaust flow (and excessive heat). It has a tube inside that directs a portion of the exhaust flow to the sensor.

Perhaps you could loosely install the sensor to where exhaust would leak past the threads to see if it will output a signal change. As far a grounds go, I have the heater ground separate from the sensor and signal grounds. The sensor and signal grounds (2 blk wires) go the MS sensor ground pin. The heater ground goes to the same engine ground point I have for the coils and injectors. I could not download the ALM-Inline manual due to a glitch, but I would assume it is the same as the other ALM products.

[Alan L]

Originally Posted by flightlead404

Alan

Can you clarify please? Do you mean there was a potential difference between where you earthed controller and the exhaust?

Was your issue the same behavior as mine?

It is a while ago now - maybe a decade. I can't remember the details - but it was not working properly - silly numbers, or would not calibrate or similar. I did have it earthed - but there was something inadequate in how I earthed it. They did say the earthing was critical.
Regards
Alan

[flightlead404]

I have the ALM inline. They specifically told me multiple times, even after I queried them about ground loop issues, to have BOTH heater ground and electronics ground tied to the same place.

It doesn't make any difference. I tried their way, and my way which is elecontrics ground to MS sensor ground and heater ground to engine ground.

I even tried, with the sensor out, to run a ground strap from the sensor to the exhaust, it did not duplication the problem.

There is PLENTY of exhaust passing the sensor. I'm convinced this is an electronics issue but its crazy!

[993Speedster]

I've heard the 4.9 are very sensitive to rapid temp changes and usually sensors read lean when they're on the way out. I'd have a second to back it against and/or replace this one when it dies (if it isn't already).

[flightlead404]

Originally Posted by 993Speedster

I've heard the 4.9 are very sensitive to rapid temp changes and usually sensors read lean when they're on the way out. I'd have a second to back it against and/or replace this one when it dies (if it isn't already).

Thanks. It's not that it "reads lean" its that it reacts as though its in free air, exactly as as does when I test it on the bench. It's a brand new sensor.

[16Volt]

This might not be relevant but where is it placed in the exhaust?

My 4.2 sensor started reading 14.5 constantly when the exhaust had melted through the wire and was touching the exhaust.

[flightlead404]

Originally Posted by 16Volt

This might not be relevant but where is it placed in the exhaust?

My 4.2 sensor started reading 14.5 constantly when the exhaust had melted through the wire and was touching the exhaust.

It's immediately after the turbo, and yes the bung is rotated 45 degrees ish from the vertical. The wires are fine.

[full quack]

Ok, here's a stupid what if......do you possibly have the polarity switched on the O2 sensor? So that when the O2 sensor is hanging in air but connected, it has current flow, but when you screw it into the bung you experience either a double ground or a double feed???

I'm sure I don't have a clue about this....just throwing it out there.

Mark

[flightlead404]

Originally Posted by full quack

Ok, here's a stupid what if......do you possibly have the polarity switched on the O2 sensor? So that when the O2 sensor is hanging in air but connected, it has current flow, but when you screw it into the bung you experience either a double ground or a double feed???

I'm sure I don't have a clue about this....just throwing it out there.

Mark

Interesting idea. No I've checked the pinouts multiple times. I don't think it would work that way anyway. There's a single +12v input and two grounds, heater and electronics.

[Bigtoe32067]

Have you tried running the ground for the controller and both grounds from the sensor directly to the engine so there can be no possible potential between the them?
Tony

[flightlead404]

Originally Posted by Bigtoe32067

Have you tried running the ground for the controller and both grounds from the sensor directly to the engine so there can be no possible potential between the them?
Tony

Yep. Tied them together at the controller end and ran a wire straight to the case.

['76 911S 3.0]

The sensor mounted in the bung should have no effect on the operation of the sensor, have you tried installing the kit on another vehicle to see if you get the same behaviour? That would at least rule out something with the vehicle...

[mark houghton]

-If I hang the sensor in the exhaust stream from the exhaust tips or from the gas stream from the empty bung hole () same thing, voltage drops, pull it away voltage goes back to 5v

Very strange. Per your comment, and someone else's suggestion that heat may be the issue when screwed in to the bung, try dangling it in the exhaust stream while at the same time heating it up with a heat gun to mimic the heat soak you would get when installed. Even the new sensor may be bad.

[flightlead404]

Originally Posted by mark houghton

-If I hang the sensor in the exhaust stream from the exhaust tips or from the gas stream from the empty bung hole () same thing, voltage drops, pull it away voltage goes back to 5v

Very strange. Per your comment, and someone else's suggestion that heat may be the issue when screwed in to the bung, try dangling it in the exhaust stream while at the same time heating it up with a heat gun to mimic the heat soak you would get when installed. Even the new sensor may be bad.

Wow, we're reaching for straws lol

I'll try that.

Another thing I'll try is screwing it into the bung while the engine is running, and see where it starts to read incorrectly.

My gut says its not head related as it seems to happen immediately rather than over time as I think it would do if it were heating up.

More data this weekend hopefully.....

[mark houghton]

Originally Posted by flightlead404

Wow, we're reaching for straws lol

I'll try that.

Another thing I'll try is screwing it into the bung while the engine is running, and see where it starts to read incorrectly.

My gut says its not head related as it seems to happen immediately rather than over time as I think it would do if it were heating up.

More data this weekend hopefully.....

Yeah, sometimes grasping at straws is all we have. Process of elimination. Weird ass problem you've got there.

[dap930]

I would e-mail Ecotrons technical support to see if they have any insight into what may be going on. When I installed the ALM-ADV for my setup the software was not correct for LSU-ADV sensor. I e-mailed them and they figured out that I had the incorrect software. Not your problem, but they may be able help figure this issue out.

[flightlead404]

Originally Posted by dap930

I would e-mail Ecotrons technical support to see if they have any insight into what may be going on. When I installed the ALM-ADV for my setup the software was not correct for LSU-ADV sensor. I e-mailed them and they figured out that I had the incorrect software. Not your problem, but they may be able help figure this issue out.

I was convinced it was a bad computer. But then I went back and tested it out of the car just by accident. Now I'm thinking I've had 3 bad new sensors in a row, but this one is not utterly dead just a bit dead. Maybe there's some internal grounding in the sensor that is bad.

In fact, I tested with a Spartan controller I just pulled out of the trash and it exhibits exactly the same behavior, that is the readings work just fine when the sensor is not screwed into the bung, and goes to 5v when screwed in.

I'm about to check all my grounds for the umpteenth time now....Done

Grounds are perfect. Electronics ground is grounded where the MS grounds, with a dedicated 16AWG line to a stud on the crank case where the airpump used to mount. Verified 0 ohms resistance between MS ground mount and several places around the case and the exhaust. Heater ground goes to frame ground in the LHS engine bay where all shields ground (old CDI grounding point).

Edit 2: Returned that sensor and got another one. Both genuine bosch off amazon definitely not the cheapest option. Will test with the new sensor this weekend and report back.