2008 Chaparral 275 SSI 8.1 Volvo Penta GXI-J Soft Alarm Issues

[apisk]

The wiring diagram I posted was from this full PDF

Agreed on the scope of this, there is the issue of the 5V being low, and the Knock Sensor for some reason being triggered by the Codes, for now I am treating them as separate with hopes there may be some relation (or false codes)

 

[tpenfield]

One thing that I did see was that the Voltage Ref#2 follows the TCP Command slightly. The voltage rises slightly as the 'Command' value goes up and lowers slightly as the 'Command' value goes down.

Is there a single connector or a few connectors for the throttle control? I am wondering if unplugging those (Ignition on, engine NOT running) will have any impact of Volt Ref #2?

 

[tpenfield]

Also, found this, which is about the same symptoms as you are seeing . . . Not sure it is any help though . . .

https://www.justanswer.com/boat/7ucr4-2010-8-1-gxi-j-engine-started-getting-alarm.html

 

[apisk]

One thing that I did see was that the Voltage Ref#2 follows the TCP Command slightly. The voltage rises slightly as the 'Command' value goes up and lowers slightly as the 'Command' value goes down.

Is there a single connector or a few connectors for the throttle control? I am wondering if unplugging those (Ignition on, engine NOT running) will have any impact of Volt Ref #2?

There is a single connector to the TCP, the attached pic is the one I replaced but you can see the connector

 

[apisk]

Also, found this, which is about the same symptoms as you are seeing . . . Not sure it is any help though . . .

https://www.justanswer.com/boat/7ucr4-2010-8-1-gxi-j-engine-started-getting-alarm.html

The main difference is that user experiences a loss of power, I never lose any power or ability to drive, I can push it to full RPMs and speed without hesitation, I just have to deal with hearing the soft alarm go off

The alarm charts also point to similar things we are seeing, the 5V reference being the main one with MIL controls and Cam/Crank as well but I tested unplugging those sensors and it was unchanged

 

[muc]

don't have much time to look at this right now but I can add this.

5V Ref #2 is a low current regulator that only feeds TCP2. When the TCP is
plugged in, 5V Ref #2 will be pulled down to approximately 4.1 – 4.2 volts. This is
normal and no attempt should be made to repair this.


I'll try to add more later.

 

[tpenfield]

Thanks @muc that is helpful to know. It would be interesting to see where the attention should shift towards.

I was surprised to see the TPS values at idle. But it could be a Volvo thing vs. Merc.

 

[muc]

A couple of things.
Didn't see the serial number. This is a "J" model and there was a serial number break during this model, might be important.
@apisk do you have a copy of the EGC Diagnostics Workshop Manual?
Had a chance to look at the most recent Diacom file.
All the recent codes (TCP,IAT+ECT) appear to be due to someone unplugging these components. Engine speed at zero.
Knock Sensor SPN 520197 FMI 4 Which translates to a DTC 0332 looks valid but was long ago. But if we look at Knock voltage #2 we see volts drop below 0.1v right around the time the soft warning comes on.
I would troubleshoot KS #2 and repair. Then clear codes and rerun the boat with Diacom.
Knock sensor is only monitored above 3000 RPMs

Edit; ECT high was a valid fault, but really along time ago.

 

[muc]

Thanks @muc that is helpful to know. It would be interesting to see where the attention should shift towards.

I was surprised to see the TPS values at idle. But it could be a Volvo thing vs. Merc.

Those number look OK to me. This engine is "Speed Based Throttle System" vs "Lever Based Throttle System" as near as I can tell, serial number might tell more.
I think Mercury has also used both of these depending on model. The only real difference (other then strategy and parameters that are loaded to the ECM) is that I don't remember Mercury ever having an engine mounted TCP. Pretty sure they only had DTS control box at the helm.

 

[tpenfield]

Those number look OK to me. This engine is "Speed Based Throttle System" vs "Lever Based Throttle System" as near as I can tell, serial number might tell more.
I think Mercury has also used both of these depending on model. The only real difference (other then strategy and parameters that are loaded to the ECM) is that I don't remember Mercury ever having an engine mounted TCP. Pretty sure they only had DTS control box at the helm.

One of the discoveries from the data was combination of the knock retard going to 5 degrees (which looks like the maximum ?) and the soft warning activating, while the load stayed about the same. This also happened when the TCP and the TPS % values were fairly far apart and the throttle control was at 50% or more.

 

[apisk]

A couple of things.
Didn't see the serial number. This is a "J" model and there was a serial number break during this model, might be important.
@apisk do you have a copy of the EGC Diagnostics Workshop Manual?
Had a chance to look at the most recent Diacom file.
All the recent codes (TCP,IAT+ECT) appear to be due to someone unplugging these components. Engine speed at zero.
Knock Sensor SPN 520197 FMI 4 Which translates to a DTC 0332 looks valid but was long ago. But if we look at Knock voltage #2 we see volts drop below 0.1v right around the time the soft warning comes on.
I would troubleshoot KS #2 and repair. Then clear codes and rerun the boat with Diacom.
Knock sensor is only monitored above 3000 RPMs

Edit; ECT high was a valid fault, but really along time ago.

Thank you so much for digging into this @muc
I have a new knock sensor coming tomorrow so I will be replacing KS #2. Is there any way to see from non running/under load data if a replacement will fix the issue, or just have to take it out for a run and watch the volts as you mentioned?

Also, the serial code sticker on the engine cover is long gone, where on these engines is the small plaque on the block that has it? I can try to find it today to get the serial number so we can finally confirm that

 

[apisk]

One of the discoveries from the data was combination of the knock retard going to 5 degrees (which looks like the maximum ?) and the soft warning activating, while the load stayed about the same. This also happened when the TCP and the TPS % values were fairly far apart and the throttle control was at 50% or more.

That TCP and TPS value variance is something @tpenfield called out as well. Is that an issue with the sensor connection between those two, or something else? I replaced the TCP as mentioned earlier in the thread, and have a replacement TPS coming tomorrow as well to see if that helps, but not sure if that's where the variance even lies

 

[tpenfield]

@apisk - I believe you have the issue posted on the THT and Marine Engine forums as well. Have there been any useful comments from those forums that should be considered?

 

[apisk]

@apisk - I believe you have the issue posting on the THT and Marine Engine forums as well. Have there been any useful comments from those forums that should be considered?

I haven't gotten a single comment on any other forum but this one. In fact, I tried to link this forum on Net Boat Talk in hopes of helping others dealing with a similar issue and I got banned

 

[tpenfield]

I haven't gotten a single comment on any other forum but this one. In fact, I tried to link this forum on Net Boat Talk in hopes of helping others dealing with a similar issue and I got banned

Yes, but don't post links to other forum sites here either.

 

[apisk]

Yes, but don't post links to other forums here either.

I definitely will not!

 

[muc]

Thank you so much for digging into this @muc
I have a new knock sensor coming tomorrow so I will be replacing KS #2. Is there any way to see from non running/under load data if a replacement will fix the issue, or just have to take it out for a run and watch the volts as you mentioned?

Also, the serial code sticker on the engine cover is long gone, where on these engines is the small plaque on the block that has it? I can try to find it today to get the serial number so we can finally confirm that

The engine plate is typically located on the port side of the engine flywheel housing, slightly below and aft of the exhaust manifold. This is copy and paste from your owners manual. I always recommend reading the owners manual.

@apisk do you have a copy of the EGC Diagnostics Workshop Manual?

They taught us in school how and where to tap the block, because it's something best done in person. Might be best for you to take it out and run it over 3000 RPM

 

[muc]

That TCP and TPS value variance is something @tpenfield called out as well. Is that an issue with the sensor connection between those two, or something else? I replaced the TCP as mentioned earlier in the thread, and have a replacement TPS coming tomorrow as well to see if that helps, but not sure if that's where the variance even lies

The variance between the two can have many many reasons. Speed based/Lever based, engine load, boats speed, etc.. I haven't seen anything that would make me question TCP/TPS. What did you find that led you to want to replace the TCP or TPS? Did you run the diagnostic program in Diacom? If I remember right it's in the fly-by-wire section.

How much does a TPS for this engine cost?

 

[muc]

Missed that your going to replace the KS? Have you done all the troubleshooting tests? Replacing the KS is last in the diag tree.

 

[apisk]

The engine plate is typically located on the port side of the engine flywheel housing, slightly below and aft of the exhaust manifold. This is copy and paste from your owners manual. I always recommend reading the owners manual.

@apisk do you have a copy of the EGC Diagnostics Workshop Manual?

They taught us in school how and where to tap the block, because it's something best done in person. Might be best for you to take it out and run it over 3000 RPM

Unfortunately I don't have the owners manual as I am not the original owner of the boat, so just going off of what I can find online. I do have a copy of the EGC Diagnostics Workshop Manual from the Diacom software