Any questions you have before you begin buying, building and installing.
#62640
One step forward two steps back.

It seems that the controller is most likely not the issue and a damaged o2 sensor is more likely the issue. After receiving a replacement controller (which I will now pay for) I removed the old o2 sensor and discovered a drop of water sitting on top of it. I now have three things to do moving forward:

Find out where the water came from
Find a new sensor replacement
Understand what I can do while I wait for a replacement

The drop of water on the o2 sensor could have either come from a leaking water gallery in the exhaust manifold or from condensation build up in the lower areas of the exhaust. I will remove the manifold to check for leaks. I will also see how much water accumulates in the fiberglass section of the exhaust where both exhaust manifolds come together before exiting at the back of the boat. It was interesting that the drop of water stayed on the sensor for a week and remained there while I unscrewed it. After running the boat on the hose there was no water on the sensor when I removed it.

Going forward, if there is a leak in the cast iron exhausts I will have to find a way to repair it? If the issue is condensation then it is not solvable and I will have to remove the sensor once I get a decent tune.

I tried to find a replacement sensor in the wrecking yard this morning. No one has seen the plug that I have and most of the o2 sensors are 4 wire. The wrecker wanted 50 USD for a cruddy 5 wire o2 sensor I managed to find. :roll: That seems to leave online as my only option. Amazon has a lot of WBO2s with the correct plug but the genuine Bosch sensors are not available. Will the replica Bosch sensors work or do I have to get the real deal?

After working on this project for about 5 months now I’m finding myself under some time pressure. My family and I are leaving the country in 7 weeks so the project has to be finished soon. I was hoping to have it completed with enough time for a few weekends of wakeboarding but it looks like it will go up for sale as soon as it’s done. While I wait 1-2 weeks for the sensors to come in, is there anything more I can do to get the tune close and potentially do a water test to check for other random issues that are sure to pop up…?
#62644
As I recall, you have it mounted in the joint between the manifold and riser. This is fine, as it doesn't provide a place for the water to collect. (for those not familiar with boats, the exhaust pipe here is going vertical, not horizontal.)

The Y pipe downstream of your risers WILL contain lots of water. The risers dump the cooling water into the exhaust stream where the riser ends (ie, 'wet exhaust'.) This provides both cooling and sound reduction, and is a requirement for all boats to prevent fires and melted hulls. The other approved option is 100% water jacketing of all exhaust pipes until they leave the boat (ie, dry exhaust). This is $$$$ and only used on boats with huge HP big overlap cams. Your Mastercraft uses wet exhaust, so after the risers there will be water.

The water you are seeing is likely condensation. It happens when idling in all boats, and a few drops aren't a concern. It's also possible, but IME unlikely, that condensation killed your sensor.

You could also have a leak in a riser or manifold. I've seen this before, and frankly it will cause some of the erratic idle behavior you've seen. But that leak will be easy to find since it will be more than a few drops. The picture below was taken of the water leak in a riser. There was no pressure on this system, I just blocked off all but one water point and poured water into the jacket. The water you see collected in a couple of minutes, but the actual leak point was too small to see with the naked eye or even a borescope.

You can also have reversion. All engines revert exhaust gasses, especially at idle. Since boats have water in the exhaust, not having too much reversion is critical since the reversion causes water to flow backwards in the exhaust. I have a slow motion video of my boat sucking water drops back up the tailpipe. Indmar built your engine with an acceptable amount of overlap, and assuming the rebuilder didn't change cams, it should be OK. It is possible to revert worse due to retarded timing, etc, but again assuming the factory cam, it's unlikely.

IF your sensor was ruined by water, my money is on a water leak. Unfortunately, manifolds can't be fixed. Stainless tube risers can be welded, but it takes a damned good welder. Cast risers of any metal can't be fixed, just like cast manifolds.

Are you positive the sensor is bad, or just assuming there isn't a calibration problems, etc? Does the Spartan not provide any diagnostics? I know my Innovate can be connected to a PC and get diagnostics, and it will flash codes via LED.
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#62647
apollard wrote: Tue Apr 25, 2023 2:46 pm
Are you positive the sensor is bad, or just assuming there isn't a calibration problems, etc? Does the Spartan not provide any diagnostics? I know my Innovate can be connected to a PC and get diagnostics, and it will flash codes via LED.
No, it seems that the Spartan 2 controller doesn't have a way to connect to the PC to get diagnostics.

I'm making sure now that the Spartan 2 controller is calibrated correctly. I've read their documentation here: https://cdn.shopify.com/s/files/1/0189/ ... l.pdf?2679 and followed this blog post on advanced calibration here: https://www.14point7.com/blogs/news/165 ... megasquirt

Basically the controller follows the behaviour outlined in the blog post.
While Tuner Studio connected to MS and is actively displaying AFR data, cycle power to Spartan 2 and write down the 2 AFRs shown by tuner studio during the first 5 seconds and then during the next 5-10 seconds. For this example lets use 13 AFR and 17.1 AFR. Now if there were no offset or linear errors present; the first 5 seconds AFR should be 13.328 AFR and the 5-10 seconds AFR should be 16.666 AFR.
After TS shows 13.3 and 16.6 AFR it then jumps up to 19.8 where it stays. Interestingly if I change the "Calibrate AFR Settings" in TS it still shows 13.3 and 16.6 AFR at startup. I haven't tested this extensively but I would have thought changing the calibration settings would have changed the startup readings coming from the controller...?

The LED light on the Spartan controller shows that the sensor is heating correctly. I put a heat lazer gun on the back of the lambda sensor and it measured 55*C (same as the exhaust). I was expecting something closer to 600*C but I guess that temperature is only at the sensor filament?

My next step is to try and bypass the controller to see what the sensor is "seeing" at each wire. The Bosch LSU 4.9 documentation is difficult for me to interpret, however from this document :
https://www.bosch-motorsport.com/conten ... SU_4.9.pdf

I understand that:

Black: Sensor's ground wire, which connects the sensor to the vehicle's ground or chassis.

Gray: Sensor's pump cell current wire, which provides power to the sensor's pump cell that pumps oxygen ions through the sensor.

Red: Sensor's heater power wire, which provides power to the sensor's heating element that heats the sensor to its operating temperature.

White: Sensor's output signal wire, which sends a voltage signal to the vehicle's engine control module (ECM) or oxygen sensor controller, indicating the oxygen content in the exhaust gas.

Yellow: Sensor's reference wire, which connects to the sensor's internal reference resistor.

My next step is to back probe the white output sensor to see if it changes with RPM or VE adjustments.

Are there any other suggestions on how I can isolate the sensor and determine its health...?
#62648
Side-note - all sensors of any source use Bosch sensor elements. It is the assembly and packaging that is affected. Not that it makes much difference to you with failures :roll: but it's the quality of assembly that is at-issue with cheap sensors. This tends to mean that if it works at all, it probably works fine, but can be prone to failure quicker or immediately due to this - or last a very long time.
#62649
PSIG wrote: Tue Apr 25, 2023 4:22 pm Side-note - all sensors of any source use Bosch sensor elements. It is the assembly and packaging that is affected. Not that it makes much difference to you with failures :roll: but it's the quality of assembly that is at-issue with cheap sensors. This tends to mean that if it works at all, it probably works fine, but can be prone to failure quicker or immediately due to this - or last a very long time.
That's interesting. Given that they are all Bosch at heart, would it be possible to wire a 4 wire WBO2 sensor with the Spartan controller?
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