Diagnostic Tool

C

Coz

Active Member
Oct 9, 2018
443
Boat Info
2008 Sundancer 310
Engines
Merc Mag 350 DTS w/Bravo III
Can anyone help educate me on diagnostic tools for my 2008 Mag 350 MPI?
I wanna be able to do basic trouble shooting. For example, right now I have a spark plug not firing and it'd be nice to know which one it is.
 




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Thats an easy check without a tool. With the engine idling, pull one spark plug wire and see if it idles worse. If it does then that's not the misfire. When you pull the correct one, the engine idle quality will not change.
 
Zoomie said:
Thats an easy check without a tool. With the engine idling, pull one spark plug wire and see if it idles worse. If it does then that's not the misfire. When you pull the correct one, the engine idle quality will not change.
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After getting zapped a few times, I'm not a fan of grabbing spark plug wires when the engine is running.
 
I ended up using a zip tie on each lead, but I still didn't like it. Once zapped, twice shy.
 
that zap is no fun that's why we use the insulated plyers. I was just trying to help the guy out and in a pinch it might get you going again. I'd love to know about a diagnostic tool for the consumer if there is one.
 
Would
Zoomie said:
that zap is no fun that's why we use the insulated plyers. I was just trying to help the guy out and in a pinch it might get you going again. I'd love to know about a diagnostic tool for the consumer if there is one.
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Sorry, I thinking about the zap made me a bit surly. Of course there are ways around that.

As far as I know, Mercruiser uses proprietary software on a laptop for diagnostics on more modern engines. Only a trained tech can get it. But I wonder if installing a VesselView mobile would get the necessary info?
 
I got VesselView Mobile for this reason.
It’s saved me a few calls to my mechanic.
I’m not sure how in-depth it goes. Would it ID a bad plug? IDK

Aside from that, I’ve seen purpose built diagnostic computers for about $900.
 
What about the Rinda diacom?
 
Don’t change just one spark plug, even if it is bad. Change them all at once. Their not really that expensive.
 
I plan on changing them all, but want to know which one is the problem in case it happens again. They're $11 each so they are pricey to do them all, especially both engines.
scoflaw said:
What makes you think you have 1 plug not firing?
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I can only get 4200 rpm instead of 4800 at wot. Since that is exactly off by 1/8 I'm guessing I have a dead cylinder. Wouldn't some kind of tester be nice.
 
Coz said:
I plan on changing them all, but want to know which one is the problem in case it happens again. They're $11 each so they are pricey to do them all, especially both engines.


I can only get 4200 rpm instead of 4800 at wot. Since that is exactly off by 1/8 I'm guessing I have a dead cylinder. Wouldn't some kind of tester be nice.
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$88.00 for plugs is only 8.8% of a boat buck.
 
Coz said:
What about the Rinda diacom?
Click to expand...
I have this software, and the same engines. I bought the software for similar troubleshooting needs. Engine-specific (ECM/PCM) diagnostics do not require Mercruiser software. Conversely, anything specific to the Smartcraft CAN bus will require CDS G3 to decode (or a custom software/hardware solution with PGN decoding for Smartcraft). This would include visibility into data like tank levels, Axius data, etc.

In the Diacom software, there is a misfire test that can be performed where a cylinder can be selectively told not to fire. Meanwhile, the engine RPM is graphed. The theory is that you can remove a cylinder from firing until you find one that doesn’t cause a reduction in RPM and that’s the “dead” cylinder.
 
stephenm27 said:
In the Diacom software, there is a misfire test that can be performed where a cylinder can be selectively told not to fire. Meanwhile, the engine RPM is graphed. The theory is that you can remove a cylinder from firing until you find one that doesn’t cause a reduction in RPM and that’s the “dead” cylinder.
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That sounds more comfortable than getting zapped.
 
stephenm27 said:
I have this software, and the same engines. I bought the software for similar troubleshooting needs. Engine-specific (ECM/PCM) diagnostics do not require Mercruiser software. Conversely, anything specific to the Smartcraft CAN bus will require CDS G3 to decode (or a custom software/hardware solution with PGN decoding for Smartcraft). This would include visibility into data like tank levels, Axius data, etc.

In the Diacom software, there is a misfire test that can be performed where a cylinder can be selectively told not to fire. Meanwhile, the engine RPM is graphed. The theory is that you can remove a cylinder from firing until you find one that doesn’t cause a reduction in RPM and that’s the “dead” cylinder.
Click to expand...

Are you happy with the software? Any trouble figuring out fault codes? I'm debating on getting the techmate instead of diacom just so I don't have to rely on a laptop in the future.
 
techmitch said:
$88.00 for plugs is only 8.8% of a boat buck.
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True, but plugs $100 turns into cap $100 and rotor, $20 X 2 for $440. So, I'm half a buck I guess.
 
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