Water temperature sensor assembly different part numbers?

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I am chasing a poor fuel economy issue.
I have an 07 bike. The listed part number is 37870-MBG-003 and it's about 50 to 60 bucks
The 2012 (and maybe others) has a part number of 37870-KRJ-901 and cost 20 bucks.
If I am going in anyway, do I want to install the newer model which looks just like the old model, or do I install the old model.
Weather I need one or not is a whole nother matter. But for 20 bucks what the hell..50 maybe not.
Has anyone put a new model sensor on an old bike?
 

Byron

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Temperature sending units are usually specific to the gauge/ecu that will read them. If the sender is not putting out the right ohm reading the gauge/ecu will be receiving faulty info. Before you buy the less expensive piece I would make sure that it puts out the right ohm ratings and that the mount and connector are identical to the one you are replacing. That being said I don't recall every hearing or reading about a sending unit going bad on these bikes.
 

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in 2008 Honda made some minor changes to the bike so 2003-2007 parts match each other and 2008-current parts match. Some changes are obvious like the front left calipers and the wiring configuration of the ECMs. This appears to be one of those changes I don't think anyone has noticed until now. I would go with the 2007 part to be on the safe side.

Some parts are interchangeable across all years but I wouldn't risk this one.
 
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JimGregory
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I wonder if the post 2008 bikes have mystical magical fuel economy issues. They changed this little bit for some reason or another. The Tstat housing is the same part number.
My bike took way to long to warm to 3 bars this morning so I am back on the Thermostat go-round. Once that is rectified I will move on to the next thing if there is still an issue.
 
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Joe
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I wonder if the post 2008 bikes have mystical fuel economy issues. They changed this little bit for some reason or another. The Tstat housing is the same part number.
Mine was always in the 42-44 range.. in the higher elevations of Colorado it magically sky rocketed into the 50s but always came back down the closer I got to Sea level. I've had 2 ST1300s and they were the same. Different locations with elevation, temperature and humidity levels probably affect it a lot as well as your own personal habits. Heck, some folks get more than 10k out of tires, what's up with that .. lol

I'd try to find someone nearby w/ST and both fill up at the same time w/same gas and take a 100 mile ride then fill up again and see if you both take the same amount of gas.
 
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JimGregory
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Mine was always in the 42-44 range.. in the higher elevations of Colorado it magically sky rocketed into the 50s but always came back down the closer I got to Sea level. I've had 2 ST1300s and they were the same. Different locations with elevation, temperature and humidity levels probably affect it a lot as well as your own personal habits. Heck, some folks get more than 10k out of tires, what's up with that .. lol

I'd try to find someone nearby w/ST and both fill up at the same time w/same gas and take a 100 mile ride then fill up again and see if you both take the same amount of gas.
I would be happy with that. This morning it was 29mpg with my definitely misbehaving new thermostat.
 
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JimGregory
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So are you still getting non-3 bar readings on the dash?
What I did was get under way immediately. I took a very long time to get to 3 bars. It was maybe mid 40's f. It's not right, no doubt now. I ordered a NEW new one.
It's hard to work on and diagnose etc when I can't ride much (work) and we are getting into real winter here. But I hate when things aren't exactly right. As always though, the bike runs fine.
 
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JimGregory
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Byron

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What I did was get under way immediately. I took a very long time to get to 3 bars. It was maybe mid 40's f. It's not right, no doubt now. I ordered a NEW new one.
It's hard to work on and diagnose etc when I can't ride much (work) and we are getting into real winter here. But I hate when things aren't exactly right. As always though, the bike runs fine.
The taking off immediately might be part of the problem. The owners manual states to wait until you get 3 bars before taking off. Taking off before 3 bars will mean it will take longer to reach 3 bars which will in turn produce worse gas mileage.
 
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:plus1:
I would not start off until you have at least 1 bar showing, then ride carefully until you have three, which you should have in a couple minutes or less.

Install new T-stat (correctly) :rofl1:
Replace lines and do TB sync.
You will be happy you did.
Keep us posted.
Standing by the white courtesy phone if needed.
 
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JimGregory
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The taking off immediately might be part of the problem. The owners manual states to wait until you get 3 bars before taking off. Taking off before 3 bars will mean it will take longer to reach 3 bars which will in turn produce worse gas mileage.
Guys that was an exercise to see if air flowing through the radiator slowed down the warm up process. It did, and in theory it shouldn't.
The first half mile from my house is downhill.

Larry it's looking like late next week till I get parts. Best to step away from the phone for a while!
Fresh dump of snow last night and of course now the roads are flowing with salt again. Ughh why do I live here.
 

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I have an 07 bike. The listed part number is 37870-MBG-003 and it's about 50 to 60 bucks
The 2012 (and maybe others) has a part number of 37870-KRJ-901 and cost 20 bucks.
If I am going in anyway, do I want to install the newer model which looks just like the old model, or do I install the old model.
Use the part that's listed for your bike unless the parts fiche says it was superseded by another. The part for the newer bikes will look the same because the assembly where it's installed hasn't changed, but you're going to be chasing your tail if it's different internally. If Honda is carrying two separate versions of the part, there's a reason. (It's like using a class 8.8 bolt in an application that calls for class 12.9 just because they look alike except for the number.)

I am chasing a poor fuel economy issue.
The amount of gas your bike consumes is governed entirely by how much fuel gets squirted through the injectors. Assuming you're not heavy on the throttle, there are a few things that will have an influence on that:

Sticky Injector Valves. If there's crud built up in your fuel system, some of it could have made its way into the injectors and is either preventing the valves from closing fully or making them lag a bit. Add your favorite fuel system cleaner (I use half of a 16-ounce can of Sea Foam) to your next two tanks of fuel and get the bike out for as many highway miles as you can and run it down as close to empty as you're comfortable (one bar is fine). Ignore the fuel economy of those two tanks, but pay attention to what it is for the two or three that follow.

High Fuel Pressure. If the fuel pressure regulator has failed (don't think I've heard of that happening) or has been intentionally adjusted high (which is what the Turbo Tom replacement is), more fuel will end up in the mixture than intended. I don't have any information about what effect the TT regulator has on fuel economy, but I'm pretty sure it's been discussed. Either way, these are probably not the droids you're looking for.

Overactive Cooling System. On older bikes, this is the classic stuck-open thermostat that leads to the coolant being too cold and the ECM trying to get the engine temperature up by adding fuel to the mixture. You've been through that already, but if you feel like testing the replacement again, the thing you want to watch for is that it's closed by the time the water temperature falls through 175. Thermostats, being mechanical beasts, may not behave the same way in both directions.

Bad Data to the ECM. Under most conditions, the ECM tries to maintain a 14.7:1 air-to-fuel ratio. The amount of air in the intake is calculated on temperature and pressure, which are measured by the IAT and MAP sensors and the final AFR is nudged toward rich if the ECT says the coolant is cold. It is entirely possible for a sensor to fail and still give plausible readings (e.g., coolant temperature reads 150 when it's actually 180) and the ECM will act on it as if it were gospel and not throw an error. The TP (throttle position) sensor also figures into how the ECM changes its behavior to meet emissions standards, and you could have a situation where the mixture remains ideal where the rest of us have it go lean and consume less fuel. Check all four sensors using the procedures listed in the manual.

HTH.

--Mark
 
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JimGregory
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Use the part that's listed for your bike unless the parts fiche says it was superseded by another. The part for the newer bikes will look the same because the assembly where it's installed hasn't changed, but you're going to be chasing your tail if it's different internally. If Honda is carrying two separate versions of the part, there's a reason. (It's like using a class 8.8 bolt in an application that calls for class 12.9 just because they look alike except for the number.)



The amount of gas your bike consumes is governed entirely by how much fuel gets squirted through the injectors. Assuming you're not heavy on the throttle, there are a few things that will have an influence on that:

Sticky Injector Valves. If there's crud built up in your fuel system, some of it could have made its way into the injectors and is either preventing the valves from closing fully or making them lag a bit. Add your favorite fuel system cleaner (I use half of a 16-ounce can of Sea Foam) to your next two tanks of fuel and get the bike out for as many highway miles as you can and run it down as close to empty as you're comfortable (one bar is fine). Ignore the fuel economy of those two tanks, but pay attention to what it is for the two or three that follow.

High Fuel Pressure. If the fuel pressure regulator has failed (don't think I've heard of that happening) or has been intentionally adjusted high (which is what the Turbo Tom replacement is), more fuel will end up in the mixture than intended. I don't have any information about what effect the TT regulator has on fuel economy, but I'm pretty sure it's been discussed. Either way, these are probably not the droids you're looking for.

Overactive Cooling System. On older bikes, this is the classic stuck-open thermostat that leads to the coolant being too cold and the ECM trying to get the engine temperature up by adding fuel to the mixture. You've been through that already, but if you feel like testing the replacement again, the thing you want to watch for is that it's closed by the time the water temperature falls through 175. Thermostats, being mechanical beasts, may not behave the same way in both directions.

Bad Data to the ECM. Under most conditions, the ECM tries to maintain a 14.7:1 air-to-fuel ratio. The amount of air in the intake is calculated on temperature and pressure, which are measured by the IAT and MAP sensors and the final AFR is nudged toward rich if the ECT says the coolant is cold. It is entirely possible for a sensor to fail and still give plausible readings (e.g., coolant temperature reads 150 when it's actually 180) and the ECM will act on it as if it were gospel and not throw an error. The TP (throttle position) sensor also figures into how the ECM changes its behavior to meet emissions standards, and you could have a situation where the mixture remains ideal where the rest of us have it go lean and consume less fuel. Check all four sensors using the procedures listed in the manual.

HTH.

--Mark
Hi Mark
I get all that thanks. I think it's interesting that Honda redesigned this part in the "08" redesign. As we know Honda does not like redesigning the ST1300. So it must have really sucked! Some parameters changed. I wonder what. I also wonder if post 08 bikes have these fuel/temp/thermostat issues. If the frequency has lessened perhaps the onboard computer is not so freaking fussy about all of it, dumping extra fuel at the drop of a hat or a couple of degrees.
 
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For what its worth.....standing back away from the white courtesy phone.....I have seen and corrected many post 08 ST1300's that have behaved like yours.
I will agree with Blrfl and treat the "sticky Injector Vales" with both Seafoam and MMO, and, Bad data to the ECM (map sensor) could also be caused by something as simple as a TB sync and/or goop in the lines.
The only other thing that comes to mind that nobody has talked about is the possibility of rodent damage on the wiring under the airbox. Keeping fingers crossed that will not be it.
Just thinking outside the box for a minute, your brakes are not dragging are they? :rofl1:
 
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JimGregory
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For what its worth.....standing back away from the white courtesy phone.....I have seen and corrected many post 08 ST1300's that have behaved like yours.
I will agree with Blrfl and treat the "sticky Injector Vales" with both Seafoam and MMO, and, Bad data to the ECM (map sensor) could also be caused by something as simple as a TB sync and/or goop in the lines.
The only other thing that comes to mind that nobody has talked about is the possibility of rodent damage on the wiring under the airbox. Keeping fingers crossed that will not be it.
Just thinking outside the box for a minute, your brakes are not dragging are they? :rofl1:
Then there you have it..
Wheels are spinning free as butterflies.
I will be happy to use up some sea foam but it will be most likely months before I can go through 2 tanks. Dead of winter and all. This is troubleshooting in New England at it's best!
Just placed an order from England from good Mr. Morgan. Looked at my stix and they not looking well. You must teach me the Morgan Mod when the time comes, and it has a chance of making sense to me.
Something to think about is, in all this time I have been screwing around with this thing and soliciting info from all you good folks, I have yet to make it to first base. I STILL don't have a properly working thermostat in it yet. Full time job, crap weather and waiting on parts are the culprits. Along with my
becoming old and a little bit stupid. It's all a little embarrassing. Lucky for me I don't care.
.:rimshot1:
 
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I don't mind helping ya, and talking to ya on the phone, but as far as making it to first base.....I ain't about to kiss ya :rofl1:
Let me know when Mr. Morgan arrives and I'll send you pictures on how mine is set up with the dampers inside the hoses and the adapters I use to plug them into the lines.
Don't be embarrassed, but I'm still not kissing ya.
 
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JimGregory
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I havent heard that term used like that in a long time. And I surely didn't mean it like that.
Anyway..I like the seafoam thing. I STILL think some smart guy like yourself should do a checklist starting with the easy/cheap stuff and ending in the most technically challenging. If all else fails. Makes good sense to attack the east stuff first. Sea foam is pretty damn easy!
Just saying.
 

BakerBoy

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Jim, tape over most of the radiator to block airflow. Simple, and easily pulled off if weather warms up during a ride. I have a properly functioning thermostat and I've fast, wide, blue painters tape on my radiator grill, 3 or 4 strips, which helps it's operating temperature. And it keeps my legs warmer too!

Of course, don't blind it over, but in the winter you can cover 50% or more without much concern (unless you're caught in stop now go traffic, then pull over and pull off the tape).
 
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