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547xs not calculating MPG at high speeds

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547xs not calculating MPG at high speeds

Old 11-08-2016, 12:28 PM
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Default 547xs not calculating MPG at high speeds

I recently had to replace my 541s, so Garmin made me a deal on a 547xs. I've got it tied into my NMEA2000 network from my Yamaha F150, pulling engine data. Has always worked great, displaying and calculating my fuel flow rates, mpg, fuel remaining, etc.

When I switched over to the 547xs I've noticed that when I'm at low/medium speeds (< 20 mph) it calculates my mpg, flow rates, etc. is all correct, but when I get upwards of 25 mph (around 12-13 GPH) my mpg readout becomes intermittent, bouncing back and forth between 0 and some other numbers (i.e .2.58 mpg). All other data remains valid (RPM, temp, fuel flow, fuel remaining, etc.) so I don't believe it's a network issue. BTW, this is the 2nd 547xs that showed these symptoms.

Does anybody know if there's a known microprocessor bug or problem that wouldn't allow this to compute properly?
Old 11-09-2016, 02:47 PM
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Is the menu speed setting input set to that GPS(SOG) , or other source such as a paddlewheel speed sender( STW.)? Whichever the source, is that reading consistently at cruise speed ( cable connection being jostled more by waves at speed?)

Does that unit have the latest SW version in case it is a bug they might have addressed?
http://www8.garmin.com/support/ch.js...t=010-01092-00
Old 11-09-2016, 02:58 PM
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Originally Posted by TTaxi View Post
Is the menu speed setting input set to that GPS(SOG) , or other source such as a paddlewheel speed sender( STW.)? Whichever the source, is that reading consistently at cruise speed ( cable connection being jostled more by waves at speed?)

Does that unit have the latest SW version in case it is a bug they might have addressed?
http://www8.garmin.com/support/ch.js...t=010-01092-00
Will need to check settings, but I believe it's set to GPS. At low-medium speeds it's constant. It's only when I get up to WOT that it seems to blank out.

I'm on v6.5 which is the latest version. I checked the release notes and didn't see anything on it. I also called Garmin support to see if they had a known bug or anything; nothing in their database.
Old 11-09-2016, 07:14 PM
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Does the speed reading remain constant or does it go away?

Do you have an external GPS puck or paddle wheel or some other speed sensor or just the internal GPS?
Old 11-10-2016, 03:17 AM
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Originally Posted by Yrral3215 View Post
Does the speed reading remain constant or does it go away?

Do you have an external GPS puck or paddle wheel or some other speed sensor or just the internal GPS?
GPS speed remains constant, all other data continues to display. I don't have any other speed devices. Just that MPG display that flat lines on me. I don't think it's a big deal, because when I'm running at WOT I'm not really worried about MPG, just wondered if anybody else had seen anything similar.

It's almost like the CPU can't keep up with the computations at those flow rates or something.
Old 11-10-2016, 06:01 AM
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That was the other thing that occurred to me. Are you using one of the Ultra mapping cards and/or running QuickDraw while your going fast?
Old 11-10-2016, 07:44 AM
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Good point! I'm using a BlueCharts card. Didn't have a problem with it in my 541s, but maybe it's a problem with the 547xs. Thanks.
Old 11-10-2016, 08:24 AM
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An easy test would be to remove the card and turn off Quickdraw and see how it does.
Old 02-16-2017, 10:15 AM
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Not in the theme, but i have just a question- does garmin 547xs has metric(meters) or just feet option on showing depth?

thank you,
Old 02-16-2017, 10:47 AM
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Originally Posted by matejs View Post
Not in the theme, but i have just a question- does garmin 547xs has metric(meters) or just feet option on showing depth?

thank you,
I believe you can select that in a systems setting somewhere.

BTW, it turned out to be a bad cable. Replaced the cable and all is good.
Old 02-16-2017, 02:12 PM
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Originally Posted by tcpip95 View Post
I believe you can select that in a systems setting somewhere.

BTW, it turned out to be a bad cable. Replaced the cable and all is good.
Glad you got it resolved as I'm currently waffling back and forth between the 547xs and 54cv for my little project. It will basically come down to which one fits in my dash the best. I've made paper prototypes from the respective templates and will going down to the boat this weekend to tape them up to the dash as a dry run. Holding out hope for the 54cv because I prefer the more squared off screen but it's going to be a very tight squeeze between my current guages, if it fits at all. The unit might just slide in there but whether the cover will go on without interference from the edge of the current guages out to either side is very much in question.

My assumption is you like the 547 though? I stood at the electronics display at WM for a couple of hours last weekend and played with everything they had. I really like Garmin presentation and system navigation over the others. Seems like all the Garmins worked pretty much the same so if you could operate one you could operate the others.

Just hoping I don't get shut out trying to run the NMEA cable to the engine. That's what Im really interested in more than anything else.
Old 02-16-2017, 02:19 PM
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Yes, I like the Garmin stuff. Subtle differences from the 541s to the 547xs, but easy enough to figure out. Wife has a Garmin 78sc that she keeps in her dry bag while on her PWC; that is a different beast. Again, once you figure it out it'll all fall into place.

Running my cable was a royal PITA. In fact, it would have been nearly impossible to do. I got lucky and just had a bad connector. I cut, spliced, and shielded the new connector, then heat-shrunk it and all is good. And you're right: That was the reason I wanted the NMEA 2000 network - just for the engine data.
Old 02-16-2017, 03:17 PM
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Originally Posted by tcpip95 View Post
Yes, I like the Garmin stuff. Subtle differences from the 541s to the 547xs, but easy enough to figure out. Wife has a Garmin 78sc that she keeps in her dry bag while on her PWC; that is a different beast. Again, once you figure it out it'll all fall into place.

Running my cable was a royal PITA. In fact, it would have been nearly impossible to do. I got lucky and just had a bad connector. I cut, spliced, and shielded the new connector, then heat-shrunk it and all is good. And you're right: That was the reason I wanted the NMEA 2000 network - just for the engine data.
Do you have it mounted in the dash? If so, how far above the face of the dash does the front of the Garmin stand? Maybe it doesn't matter if the unit runs right up against an adjacent gauge if the profile is high enough that the cover has a little clearance underneath the edge.
Old 02-16-2017, 03:23 PM
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No, mine is bracket-mounted, so that I can remove it and put it in my bag to take home.

Like the Freedom Through Vigilance
Old 02-16-2017, 03:28 PM
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Originally Posted by tcpip95 View Post
No, mine is bracket-mounted, so that I can remove it and put it in my bag to take home.

Like the Freedom Through Vigilance
Truth be told I'd probably rather do mine that way too but the Admiral is giving me grief about possibly drilling holes in the boat. Can't say I'm crazy about the idea either. At least with the dash mount if I foul something up I can get another one fabricated and restore everything to as new condition.

But somehow she's got it in to her head that this is her boat...
Old 02-17-2017, 01:16 PM
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Originally Posted by tcpip95 View Post
No, mine is bracket-mounted, so that I can remove it and put it in my bag to take home.

Like the Freedom Through Vigilance
And the winner is the dash-mounted Echomap 54cv. The template is the outline with the cover included. I have about 1/8" clearance between the cover and the gauges on either side, about 3/8" clearance with the cover removed.

Looked for a good place to ram mount one and just couldn't find a spot that really tickled my fancy. And this will keep the admiral happy since I won't be cutting in to the hull proper.

I think (fingers crossed) I've also found a not-too-difficult path to get the engine wire to the stern. Going back with my fish tape and some string this weekend for another dry run.
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Old 02-17-2017, 01:19 PM
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Originally Posted by gbchriste View Post
And the winner is the dash-mounted Echomap 54cv. The template is the outline with the cover included. I have about 1/8" clearance between the cover and the gauges on either side, about 3/8" clearance with the cover removed.

Looked for a good place to ram mount one and just couldn't find a spot that really tickled my fancy. And this will keep the admiral happy since I won't be cutting in to the hull proper.

I think (fingers crossed) I've also found a not-too-difficult path to get the engine wire to the stern. Going back with my fish tape and some string this weekend for another dry run.
Good for you. Looks like it'll fit perfectly. Good luck with that cable. Hope it pulls easily.

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