engine oil temp sensor

[dlaing]

There. That should get at least somebody grumbling.

That was about the most sensible post yet!

The only thing I might lean toward disagreeing with, is that I SUSPECT that the plastic was spec'd for reason of insulating the sensor from the engine, but yah, I'd agree we don't know that for better than 99% certainty. I am only about 95% certain. Skeeve is probably about 5% certain, RH is certainly uncertain or certain or something.

[Dan M]

That was about the most sensible post yet!

The only thing I might lean toward disagreeing with, is that I SUSPECT that the plastic was spec'd for reason of insulating the sensor from the engine, but yah, I'd agree we don't know that for better than 99% certainty. I am only about 95% certain. Skeeve is probably about 5% certain, RH is certainly uncertain or certain or something.

 

 

This has been the heart of my theory from the beginning of this debate. I feel the plastic is used to slow response. To smooth out the extreme temp changes of an air cooled engine.

Sorry if I'm being redundant here and I really don't want to start over from page 8 but think of it this way. You are riding a warmed up bike on a warm day. You come to a traffic light for a several minutes. Head temp increases greatly. There is no need to further lean the mixture. If anything, you want a rich mix to help keep the temp down. You take off and the head cools pretty quickly. No need to enrich. On a liquid cooled engine the temp will stay more constant once warmed up and the mixture will as well. A plastic holder and corresponding air gap removes the temp spikes from the equation, mimicking the temp signal seen on a liquid cooled engine.

[Guest ratchethack]

. . .You are riding a warmed up bike on a warm day. You come to a traffic light for a several minutes. Head temp increases greatly. There is no need to further lean the mixture. If anything, you want a rich mix to help keep the temp down. You take off and the head cools pretty quickly. No need to enrich. On a liquid cooled engine the temp will stay more constant once warmed up and the mixture will as well. A plastic holder and corresponding air gap removes the temp spikes from the equation, mimicking the temp signal seen on a liquid cooled engine.

Aye. That's been my read since about page 8 myself, Dan. I believe it's substantially supported by the results I've achieved by adding thermo-paste, heat sink, and variable resistor to the OE plastic sensor/holder above -- the only alternative to running acceptably well under full operating temps at idle, off-idle, and low RPM with no thermo-paste with my PC III map.

 

Careful, though. If you've the bald-faced temerity to post this understanding, a surprising few will come out o' th' woodwork with accusations of heresy, thinking in and out of boxes, taking sugar pill placebos, and o' course, bolting on square wheels.

 

Nosiree, Bob. . .Some don't seem to like this kinda thing a-tall. . .

 

 

. . . But waddayagonna do?

[fotoguzzi]

so, should I keep my plastic holder and get a PC3? is that what it boils down to? (liquid pun intended)

[Dan M]

so, should I keep my plastic holder and get a PC3? is that what it boils down to? (liquid pun intended)

 

Foto,

 

I remember seeing your bike at VBRII (I may even have a foto somewhere) but don't remember if you had stock exhaust. If you've made any exhaust mods a PC3 is essential.

[raz]

It would depend on the fault. If disconnected I think it would run lean.

I believe it would run very rich. If the sensor is disconnected, the bridge resistor will pull the signal to the ceiling at 5V. The ECU will either interpret that as your engine is colder than -40°C or, hopefully, trigger some kind of fault mode and disregard it.

 

See, we can keep this thread running

[Guest ratchethack]

I believe it would run very rich. If the sensor is disconnected, the bridge resistor will pull the signal to the ceiling at 5V.

This is exactly what it does, as I would expect. I just did it. Starts up just fine, runs fine, smells rich.

 

This might be just the thing to do to verify an over-lean condition and ragged running at idle when hot.

 

. . .If you can get it disconnected without a nice collection of 2nd-degree burns, that is. . .

[fotoguzzi]

Foto,

 

I remember seeing your bike at VBRII (I may even have a foto somewhere) but don't remember if you had stock exhaust. If you've made any exhaust mods a PC3 is essential.

that rally was a lot of fun! but was it ever windy.. I did 95-100 w/a couple Beemers all the way home down the slab.

 

[Greg Field]

so, should I keep my plastic holder and get a PC3? is that what it boils down to? (liquid pun intended)

 

The plastic holder works fine, unless it cracks. Usually, it doesn't crack until you try to remove it. If everything's OK, leave it alone. If your bike shows symptoms of wonkiness related to temp sensing (usually manifested as poor fuel mileage), you might want to play with it. What often helps is to put the sensor tip in thermal contact with the copper bit put there to transfer temp to the tip. You can do this by draw-filing down the plastic housing until the tip contacts the copper or by adding some sort of goop to transfer the heat. Or you can kludge up a monstrous device made up of sixteen microprocessors and a half dozen field-loop thrunge gromenators to accomplish the same thing.

[Dan M]

Or you can kludge up a monstrous device made up of sixteen microprocessors and a half dozen field-loop thrunge gromenators to accomplish the same thing.

 

 

Sounds like fun. You're still in the midst of winter up there eh foto. I say you get crackin' and don't forget to show us pics of the control center when finished.

[dlaing]

I believe it would run very rich. If the sensor is disconnected, the bridge resistor will pull the signal to the ceiling at 5V. The ECU will either interpret that as your engine is colder than -40°C or, hopefully, trigger some kind of fault mode and disregard it.

 

See, we can keep this thread running

I assumed it would simply read 0V, but I'll trust your knowledge of this bridge resistor, as backed up by RH's observation.

Thanks!

[dlaing]

The plastic holder works fine, unless it cracks. Usually, it doesn't crack until you try to remove it. If everything's OK, leave it alone. If your bike shows symptoms of wonkiness related to temp sensing (usually manifested as poor fuel mileage), you might want to play with it. What often helps is to put the sensor tip in thermal contact with the copper bit put there to transfer temp to the tip. You can do this by draw-filing down the plastic housing until the tip contacts the copper or by adding some sort of goop to transfer the heat. Or you can kludge up a monstrous device made up of sixteen microprocessors and a half dozen field-loop thrunge gromenators to accomplish the same thing.

The two do not accomplish the same thing.

Your method is like taking a square wheel, turning it into an octagon and calling it round

Adding thermal transmitting goop speeds up and increases the temperature reading, reducing the over-enrichening at low engine temps. Field loop gromenators controlled by microprocessors if properly applied would result in a much more ideal fuel mixture, much more of the time.

Heck even RH got more than half way closer to nirvana than your method could, with a microprocessing PCIII, some thermal goop, some cooling fins and a variable resistor

If I ever get my Windoze machine working, I'll be modifying the temperature maps, which is in another way to get half way to Nirvana.

I am skeptical about cooling fins, but resistors are an excellent idea, IMHO.

[Guzzi2Go]

Here are the voltages¹⁾ and, more importantly, what the ECU reads²⁾. The ADC column is what the AD converter should end up with. It's an integer between 0 (0 volts) and 1023 (5 volts).

 °C	 ohms	  mV	ADC
...
25	 3000	3333	683
30	 2420	3087	632
40	 1600	2581	529
50	 1080	2093	429
60	  750	1667	341
70	  525	1296	265
80	  380	1011	207
...

 

^{1, 2)} this is based on the assumptions the ECU use a 1K5 fixed bridge resistor and a 10 bit ADC, like MyECU. I do not know for sure if that is the case.

HA!!! WELL DONE RAZ, WELL DONE!!!

 

Finally someone puts a few numbers "on paper" and comes up with a plausible explanation. I am fishing for this kind of argumentation for quite a while now, but it seems that our "scientists" are more inclined to writing essays on philistines, sincerity and seat-o-pants experimenting methods then to pulling out their r(d)usty calculators and doing things that an 8-year old could do.

 

Once again, well done!!!

 

Everyone, how about some rough models/calculations on influence of air gap, heatsink, resistor, whatnot? The ones that include some numbers rather then descriptions of your seats of pants?

[Guzzi2Go]

Now you are losing me G2G.

The oil temp sensor as guzzi calls it is a coolant temp sensor in any other application - brass sensor probe designed to be submerged in coolant. Part #29729461 The air temp sensor is exactly that. A plastic sensor body with an exposed thermistor probe designed to sense air temp. Part # 30729331

Two completely different sensors for two different purposes. I'm quite sure they are spec'd to be accurate in the ranges needed.

This is what I mean Dan - http://www.dpguzzi.com/efiman.pdf

 

Look at the page 12 of the PDF. True, different part types, but identical NTCs.

[raz]

Regarding at what temperature the thermistor is most accurate I'm not sure if you or Dan is [this grammatical incident beats me. You are, he is, you and he are, you or he... are?] wrong, or both. I'm leaning towards you are both right but are looking at in from different views

 

I think it's Accurate Enough [tm] for air and oil temps in a Guzzi pump that is, if it's correctly mounted...

 

Ideally my air temp sensor should be mounted INSIDE the air filter box, not near the triple clamp. And the oil temp sensor should sit in the sump, immersed in oil, or be called something else.