Lowrance HDS7 displaying incorrect engine temperatureon my Yamaha F150

[scottcmb1965]

Hey guys,
I Have a 2010 Yamaha F150 installed with the Yamaha Command link system connected to the three Yamaha square gauges ( Speed, Tach and Fuel Management). I am also running a Lowrance HDS7 that is linked into the "Multi hub" for extra various engine readings.
Everything that I want to display on the HDS7 about the engine is reading perfectly, accept for the "Engine Temp" reading. The reading on the HDS7 is reading about 12 degrees Centigrade lower in temperature compared to what the temp reading is on my laptop using YDS software.
Eg: This morning I hooked up my laptop and switched on the motor and the Lowrance, both temperature readings at cold were the same "16 degrees C" on both the displays. I started the engine and watched the readings as it was warming up to idle operating temperature... both would increase the same together until at about 48 degrees, this is when the YDS would start increasing higher than the reading on the Lowrance at a gradual rate..... and finally when the YDS reading stabilises at 62 degrees the lowrance is displaying 50 degrees...... its weird!!

The other readings : Oil pressure, MAP pressure, water pressure etc are all reading identical between the YDS, Lowrance and Gauges. Its just the "Engine temp" that is not playing ball. I have also done a physical check of the "Actual" engine temp with a digital temp gun aimed at the lug that the engine temp sensor is screwed into and its reading identical to what is displayed on the YDS ( did that for piece of mind).

Does anyone have a solution to this problem or any clues?.... I have been through the settings on the Lowrance but there is nothing relating to it for options.

Cheers
Scotty

[fairdeal]

Fascinating - first I've read of anything like this -

although probably very few people take the trouble to simultaneously compare the N2K output to the YDS !

you must have noticed that the engine always "runs cold" - according to the Lowrance ? is that why you pursued this?

I'm thinking there has to be a software "bug" in either the ECU programming or the Lowrance -

either the ECU is incorrectly converting the value to N2K format before broadcasting it,

or the MFD is incorrectly converting the N2K value to display it

You need a "tiebreaker" - what about your Command Link gauge ?

how many "bars" do you see?


Guess you have to connect a different MFD to your network.


Or get yourself a N2K-to-PC converter!

Actisense - Overview

I wish the price of those was lower - would love to be able to "see" the full N2K stream of my F225 - not just what my Garmin shows me.

Probably the most sensible start is a phone call to Lowrance Support to see if they have heard anything of this...

[scottcmb1965]

You are correct, I did notice the reading to be on the cold side of things when running the boat out on the water so I investigated it further, thinking maybe a slightly stuck open thermostat or faulty one. After completing a check and test of the thermostat and finding it is perfectly in spec and nothing wrong at the thermostat housing, that's when I decided to hook up the laptop and see what the YDS was reading and that's when I discovered the difference.
The command link gauge reading shows the indicator sitting in the middle of the scale when at idle temperature and then slightly rises when under load as you would expect, so at this stage I'm guessing that the scale is a 0 ~ 120 degree C scale. Its a pity that you don't have the option to change the "Eng Temp" reading to a numerical value on the Command link gauge like you can with the water pressure reading, and also in the Command Link Manual it shows what each bars value equals on the water pressure scale but nothing for either oil pressure or Engine temp which I find quite strange with there designing..... like "Why have they done it for water pressure but not for these other VERY important engine readings!"...... Yamaha Dumb As#&s!!.
I am thinking at this stage like you suggested that the problem probably lies in the Lowrance logic and that its a bug that needs correcting, as I have noticed that the same "Cold Temp Reading" problem exists when also running a 2007 Yamaha F115 with the same setup.
I am going to contact Lowrance and let them know what I have found and ask if they are aware of it and if there is a "Fix" for it, but I wont be holding my breath, I will probably get the usual " No problem with our product must be a Yamaha ECU problem go see them " etc lol.

Any way.... thanks for your reply
Cheers
Scotty

[boscoe99]

With two devices it is difficult to tell if one is hotter than normal or if the other is colder than normal. I would not place any more confidence in the laptop display than I would in the Lowrance display.

Or maybe they are both off just a bit, each in a different direction.

Do absolute values really matter in this case?

[fairdeal]

With two devices it is difficult to tell if one is hotter than normal or if the other is colder than normal. I would not place any more confidence in the laptop display than I would in the Lowrance display.

Or maybe they are both off just a bit, each in a different direction.

Do absolute values really matter in this case?

A bit surprised to see you say that about YDS.

One would certainly hope that the YDS temperature value is "right" - since that is what the ECU "believes" -

and uses to adjust ignition timing, fuel injection timing, and fuel injection volume -

yes?

And FWIW the OP reports "verifying" the YDS temperature using a standalone thermometer.


My take on this is, that it is not a "measurement" issue -

there is only one measurement being taken and the ECU is doing it correctly



it is a "reporting" or perhaps, "translation" issue

in simply displaying the ECU's measurement on the external "gauge" of the Lowrance


Does it matter - no, since it appears the engine is actually running properly.

[scottcmb1965]

With two devices it is difficult to tell if one is hotter than normal or if the other is colder than normal. I would not place any more confidence in the laptop display than I would in the Lowrance display.

Or maybe they are both off just a bit, each in a different direction.

Do absolute values really matter in this case?

You got to be kidding right?

[scottcmb1965]

Ok.... a bit more info to add from a test out on the water today with the laptop hooked up. When under load at 5,000rpm and higher, the temperature reading on the YDS was reporting 79 degrees C and the Lowrance was reporting 58 degrees C. Thermo Gun temperature check done again gave a reading that perfectly matched the reading on the YDS....... so the ECU is receiving accurate readings from the "Engine Temp Sensor"
So it appears that that the difference between the readings on the YDS and Lowrance is increasing as the engine gets hotter when under 75%-100% loading.
In looking at this pattern my point is, just imagine what the reading on the Lowrance would be if the engine starts to run at say an "Actual" 90 Degrees C from a cooling blockage or what ever...... the Reading on the Lowrance will most likely report a temperature of say 66 Degrees C.

That's not good and accurate and reliable enough in my book!!!
Especially when there are people out there using this Lowrance option of "Engine Data" display and relying on the information they are reading from it.

Cheers
Scotty

[fairdeal]

....if the engine starts to run at say an "Actual" 90 Degrees C from a cooling blockage or what ever...... the Reading on the Lowrance will most likely report a temperature of say 66 Degrees C.

That's not good and accurate and reliable enough in my book!!!
Especially when there are people out there using this Lowrance option of "Engine Data" display and relying on the information they are reading from it

well, I made a half-jest here in a thread about the value of cooling-water pressure gauges;

said I had one on my Montauk 17, prominently placed in the center of the dash.
The water pickup on that F90 Merc-aha was oddly prone to plug with weeds while cruising.

I said that the water pressure gauge was very valuable;

whenever "out of the blue" the motor abruptly went into rpm reduction and the horn blared,

I could look right down and see that the pressure had dropped...

[boscoe99]

You got to be kidding right?

Not kidding at all.

[boscoe99]

Ok.... a bit more info to add from a test out on the water today with the laptop hooked up. When under load at 5,000rpm and higher, the temperature reading on the YDS was reporting 79 degrees C and the Lowrance was reporting 58 degrees C. Thermo Gun temperature check done again gave a reading that perfectly matched the reading on the YDS....... so the ECU is receiving accurate readings from the "Engine Temp Sensor"
So it appears that that the difference between the readings on the YDS and Lowrance is increasing as the engine gets hotter when under 75%-100% loading.
In looking at this pattern my point is, just imagine what the reading on the Lowrance would be if the engine starts to run at say an "Actual" 90 Degrees C from a cooling blockage or what ever...... the Reading on the Lowrance will most likely report a temperature of say 66 Degrees C.

That's not good and accurate and reliable enough in my book!!!
Especially when there are people out there using this Lowrance option of "Engine Data" display and relying on the information they are reading from it.

Cheers
Scotty

How is the data being relied upon? At what engine temperature is the user (you in this case) supposed to be concerned with? Does Yamaha say this anywhere?

Do you know the engine temperature at which the alarm will sound based on what the engine temperature sender is telling the ECU?

Where did you take your temperature measurement from?

You can always make a temperature correction chart so that you can back into the YDIS temperature from the Lowrance temperature.

[boscoe99]

A bit surprised to see you say that about YDS.

One would certainly hope that the YDS temperature value is "right" - since that is what the ECU "believes" -

and uses to adjust ignition timing, fuel injection timing, and fuel injection volume -

yes?

And FWIW the OP reports "verifying" the YDS temperature using a standalone thermometer.


My take on this is, that it is not a "measurement" issue -

there is only one measurement being taken and the ECU is doing it correctly



it is a "reporting" or perhaps, "translation" issue

in simply displaying the ECU's measurement on the external "gauge" of the Lowrance


Does it matter - no, since it appears the engine is actually running properly.

The thing that matters is if the warning horn sounds and the motor goes into RPM reduction mode. In which case turn off the darn motor. What is seen in the form of a temperature reading on a gauge does not matter a wit.

The block where the temperature sender is mounted, reports block temperature to the ECU. There is also a thermoswitch that is mounted elsewhere on the motor. The switch could very well close at a temperature much lower than is seen at the mounting boss for the sender.

[fairdeal]

The thing that matters is if the warning horn sounds and the motor goes into RPM reduction mode. In which case turn off the darn motor. What is seen in the form of a temperature reading on a gauge does not matter a wit.

Agreed - hence my re-telling of wp gauge joke

The block where the temperature sender is mounted, reports block temperature to the ECU. There is also a thermoswitch that is mounted elsewhere on the motor. The switch could very well close at a temperature much lower than is seen at the mounting boss for the sender.

I rather think it does - the SM tells us it is expected to close as low as 183 F and no higher than 194 F.

Pretty sure I've seen my ECM (via N2K) showing block temp higher than 195 for several minutes at a time, with no alarm.

What is still unresolved, for me,

is to verify Rodbolt's claim that BOTH the sensor and switch are needed to alarm -

that neither one switch, nor both switches together will do it "by themselves".

The little testing I did, only showed that he may well be right...

[boscoe99]

Agreed - hence my re-telling of wp gauge joke

I rather think it does - the SM tells us it is expected to close as low as 183 F and no higher than 194 F.

Pretty sure I've seen my ECM (via N2K) showing block temp higher than 195 for several minutes at a time, with no alarm.

What is still unresolved, for me,

is to verify Rodbolt's claim that BOTH the sensor and switch are needed to alarm - I don't think so. Either or should do it.

that neither one switch, nor both switches together will do it "by themselves".

The little testing I did, only showed that he may well be right...

It would only make sense to me if either the left head thermoswitch, or the right head thermoswitch, or the block thermosensor independently set the alarm.

This from Yamaha F225 data confirms my belief. Now is the Yam data and my belief correct?

OVERHEATING CONTROL
If the engine speed is under 2,000 r/min, the system does not enter the control mode for 75 seconds. However, if the engine is operated at over 2,000 r/min for more than 25 seconds, the control mode will be activated. The system enters the control mode after the specified length of time given above has elapsed, when the thermoswitch is activated, or the engine temperature reaches 120 °C (248 °F) or higher.

[fairdeal]

It would only make sense to me if either the left head thermoswitch, or the right head thermoswitch, or the block thermosensor independently set the alarm.

This from Yamaha F225 data confirms my belief. Now is the Yam data and my belief correct?

OVERHEATING CONTROL
If the engine speed is under 2,000 r/min, the system does not enter the control mode for 75 seconds. However, if the engine is operated at over 2,000 r/min for more than 25 seconds, the control mode will be activated. The system enters the control mode after the specified length of time given above has elapsed, when the thermoswitch is activated, or the engine temperature reaches 120 °C (248 °F) or higher.

No one who understands english could interpret that any differently.

nonetheless Rodbolt - from his substantial experience? or his Yamaha classroom training? believes differently.

In my testing, one shorted thermoswitch had no effect despite >120 seconds - of idling.

Both thermoswitches shorted simultaneoously had no effect through ~7 minutes - of idling.

And - inadvertently - both thermoswitches were already shorted when I attached the resistor to simulate an overheated thermosensor.

So it seems, to absolutely prove Rodbolt right & the Yamaha document wrong, I need to perform two more tests with the engine running "normally": for an extended period throughout it full operating range (not just at idle)

1. with the thermoswitches shorted but the thermosensor undisturbed

2. with the 2k resistor connected to the thermosensor harness without shorting the switches

[fairdeal]

oh - an "aside" to the thermosensor test I performed:


It was about 80 F here the day I was playing with the engine, it was idling smoothly - "normally" - while I had it running with the thermoswitches shorted.

When I started it again after swapping the 2K resistor for the thermosensor, it ran real ragged -

obviously not liking the conditions the ECU was "mapping " for a 245 F operating temp!