engine oil temp sensor

[Bruce Reader]

Who has had a dynoed map done with the brass temp holder and what differences in temp compensation, fueling etc to the original map ?

 

Does anyne actually have an out of factory map to start a baseline with ?

 

At least Ratchet is collecting some data that may point towards what will be needed to be tinkered with ?

 

Cheers

 

Bruce

 

p.s I havent had a look at thy myecu page yet but maybe they have some answers with different holders etc.

[Greg Field]

The only thing dyno-tuning with a PCIII can affect is fueling. Square tires, on the other hand, can affect many things, as only those who eschew Groupthink and Think Outside the Box (which is the new box) will ever be privileged to discover . . .

 

I can't help but think it's kinda funny people now claiming the gap is necessary, when you didn't even know there was one until I told you:

 

http://www.v11lemans.com/forums/index.php?...t=0&start=0

[Bruce Reader]

I dont have any data at hand at the moment but the last map i had done (not pc III) i was told that it needed a lot more fuel (i think across a majority of the map-i dont know).

 

This was post replacement with the brass holder. This was also after head shave, possible different cam (breva rather than v11 as the part catalogue at one stage listed just 1 V11 cam from guzzi which i've since been told has seperate listing again) and intake work.

 

I had put the fueling need down to a shorter intake time or lift with the breva cam. I know there are a lot of variables in this example.

 

The mechanic has just opened his own service centre post a dealership closing and i will talk with him about some specifics.

 

I assume the original map for this bike was done with the bike as dilivered-gap and plastic holder. I assume the map was tested to run well at idle at hot ambient temp. I assume at high speed at same ambient temps that wind chill will vary the temp reading as opposed to sitting at the lights.

 

I know the plastic doesnt last so is the answer at the software end with a brass sensor ? Does the environment cause for the sensor to be variable other than just resistance. Hence the heat sink and insulation principles talked about already in regard to plastic, air gaps and air flow cooling of the material holding the sensor.

 

Can these bikes have a totally different reaction with a brass temp sensor holder when they are at idle at the lights in southern california and Seattle ? Accumalitive heat soak difference. They are maybe both fine at high speed long runs but they show up at standstill ?

 

Cheers

 

Bruce

[dlaing]

My, my. How the Winter of our discontent doth seem to be flushed out when it's cold outside.

 

Well, best get all the bad baggage out on the table so as to separate the wheat from the chaff, I suppose.

 

Though there still seems to be lots more chaff piling up as we go forward, I'm still finding significant value in this, and learning as I go, so I reckon I'll be at it for at least awhile longer. . .

 

For those who've made up their minds that this is all complete and utter balderdash, and that my understanding of what I'm observing here is entirely backwards, I most enthusiastically welcome you to completely ignore everything you don't follow here. I've done the same with some of the above posts, and I reckon I'll do the same with many to follow.

 

As noted previously, my Guzzi with it's current PC III map runs more than acceptably well with considerable "slop" in the accuracy of the temperature read when there's no direct thermo connection between plastic holder base and sensor tip via thermo-paste. I've found it interesting lately to explore the other end of the accuracy spectrum by making that thermal connection as direct as possible, and observing the effects on driveability. So far, the only change I've made that allows me to even ride the bike with thermo-paste in there is the addition of the heat sink, as noted above.

 

For anyone sincerely interested, I've made some assumptions above about the operation of the sensor. Do with them what you will. All further assumptions below made on the basis of direct thermal contact (thermo paste installed) between plastic holder and sensor tip.

 

The thermistor presumably reads the temperature at the "probe" end, not at the sensor body. The probe end and sensor body can be, and often are, separated by different temperatures, depending on state of engine dynamics and operating mode, though the two are connected within the same relatively massive lump of brass. I b'lieve these are safe enough assumptions, but that's just me.

 

Now then. Being a relatively massive lump of brass, the sensor body acts as a heat reservoir. I think of the probe as a skinny "arm" of the sensor body, through which temperature flows as fuel flows from a fuel pump filler nozzle into a gas tank. Being thermally connected, as the engine warms up, the sensor body will draw heat off the probe until the body warms up to the same temp as the probe. Conversely, (this is where the fuel analogy isn't all that appropriate) the relatively massive sensor body will flow heat back into the probe when the probe cools. In this way, with heat constantly flowing back and forth, it makes sense to me that there's an unwanted "lag time" -- particularly when heat is flowing back into the probe tip from the relatively more massive sensor body, which would seem to be particularly problematic for an accurate read, often producing an unwanted over-lean condition at operating temp in my own case, and evidently the reverse in others suffering from extended warmup problems. I b'lieve this understanding fits perfectly with my observations of over-lean running at idle and low RPM with the motor at full operating temp.

 

By introducing a heat sink to the sensor body, the heat is flowing much more in one direction only than it is in both directions, as it is rapidly drained from the heat reservoir on a constant basis, from the probe and into and away from the sensor body. I sincerely doubt that the temperature of the cylinder head sensed at the probe tip (where the drop in resistance is generated by the thermistor, as read by the ECU) can be significantly distorted by drawing heat off the sensor body through the heat sink, since the sensor body is not the part of the sensor where the thermistor reads the heat. When the motor is shut off at full operating temperature, the un-heatsinked sensor body can (and does) retain significant heat, keeping the probe end at a high temperature for an extended period of time. A heat sink on the sensor body would seem to thereby provide a more accurate match to the actual temp at the cylinder head under all conditions, but that's just me.

 

The evidence I have to support this is 1. the very significantly improved driveability at full operating temp with the heat sink installed vs. the unacceptably poor driveability without it, and 2. the lack of "heat soak", aka "vapor-lock" symptoms with the heat sink installed, vs. the presence of same symptoms without the heat sink, thermo-paste used in both scenarios.

 

Again, I'm not making any EUREKA! claims of discovery of hidden secrets here. I'm just experimenting by trial and error, as stated up front, and honestly posting my observations and my understanding thereof. With the weather clearing up nicely today, another longish ride with longer-term careful observations would seem to be in order.

 

And so it is!

 

Will advise (Part VII).

For the heat to "flow" in the two directions with no heat sink and one direction without, you seem to be speculating that the probe temperature will be LOWER than sensor body's temperature.

I absolutely positively disagree with that theory.

Adding the heat sink is going to do one thing, lower the temperature, period.

How much it lowers it will depend on weather and riding velocity.

Look for greater cooling in colder, wetter weather, at higher speeds.

Look for less greater cooling in the dreaded conditions of hot dry weather at low speeds, which are conditions more likely to cause the problem we are trying to avoid.

The heat sink is working for you, because it is making your bike run richer, which at 40+MPG, it probably benefits greatly from.

insulating the sensor threads with teflon tape rather than adding a heat sink, should have a similar effect of lowering the temperature reading, but with less temperature reading variability induced by various weather and velocities.

Blocking the wind flow to the sensor might also help keep it from running too rich.

Heck, if you put a wind shield in front of your heat sink, you may have a great solution!

Best of luck to you.

[dlaing]

I know the plastic doesnt last so is the answer at the software end with a brass sensor ?

It is the answer I am going to shoot for, but there are many possible answers.

Personally, I'd like to switch back to the plastic sensor, put conductive at the probe, rather than an air gap and map it more like the MGS01.

 

Does the environment cause for the sensor to be variable other than just resistance. Hence the heat sink and insulation principles talked about already in regard to plastic, air gaps and air flow cooling of the material holding the sensor.

Not sure what you mean exactly, but yah, the environmentor weather plays a major factor here.

 

Can these bikes have a totally different reaction with a brass temp sensor holder when they are at idle at the lights in southern california and Seattle ? Accumalitive heat soak difference. They are maybe both fine at high speed long runs but they show up at standstill ?

My bike runs great below 60°F

The hotter it gets the more low speed crap running I get.

This was not a problem before I switched to the brass sensor adapter.

[dlaing]

I am a new V11 Lemans owner and I have been brousing this forum often, and enjoying it very much.

 

One thing I don't understand about this thread is what does this sensor in the head control? I think there is also an air temperature sensor, isn't there?

 

Would it not be the case that the cylinder head temperature sender would control only the warm up. And the mixture control after a certain temperature had been reached would then be controled by the air temperature sender?

 

I notice that my bike idles fast until it has been warmed up for about two minutes. It is clearly running very rich during this time, it makes black smoke when you rev the engine. Once the bike is warmed up for a very short time the idle speed suddenly slows down. It is like a swich is being turned. I think this is the head temp sender causing this.

 

Obviously if this sender is not working, it will cause big problems, but does the exact temperature of it's operation really make all that much difference?

 

Nigel

The ECU enrichens after startup for specific RPM count. Tuneboy has no control over this RPM count, and I don't think there is any software available to us that can control this feature of the ECU.

But there is a map field labeled "startup" or something like that. Not sure if it is related.

 

Tuneboy and Direct Link can modify the enrichment maps that are used with the Engine temp, Air temp, and Air pressure sensors.

I think the exact temperature reaching the engine temperature sensor does make a difference. The observations of people like Ratchet and I who have tried the brass sensor with negative results backs up theory. Also, looking at the maps backs up the theory, but without reading the sensor output at various riding conditions we can't be 100% sure.

[Guest ratchethack]

For the heat to "flow" in the two directions with no heat sink and one direction without, you seem to be speculating that the probe temperature will be LOWER than sensor body's temperature.

I absolutely positively disagree with that theory.

Hm. Thanks for the input, Dave. You seem to be sincerely interested. However, Your first sentence above makes no sense. Again, here's what I posted about the direction of heat flow within the sensor:

. . .by introducing a heat sink to the sensor body, the heat is flowing much more in one direction only than it is in both directions [within the sensor], as [heat] is rapidly drained from the heat reservoir on a constant basis, from the probe and into and away from the sensor body. I sincerely doubt that the temperature of the cylinder head sensed at the probe tip (where the drop in resistance is generated by the thermistor, as read by the ECU) can be significantly distorted by drawing heat off the sensor body through the heat sink, since the sensor body is not the part of the sensor where the thermistor reads the heat. When the motor is shut off at full operating temperature, the un-heatsinked sensor body can (and does) retain significant heat, keeping the probe end at a high temperature for an extended period of time. A heat sink on the sensor body would seem to thereby provide a more accurate match to the actual temp at the cylinder head under all conditions, but that's just me.

There's been no speculation above, Dave, and it isn't theory, either. I've made some assumptions about the nature of the sensor based on objective observation and simple thermodynamics, of which I consider myself fairly competent from knowledge based on both academic training (bachelor's degree in Biochem with emphasis in Physics) and hands-on experience, both of which I've relied upon here.

 

You may disagree with my observations and assumptions, and you're more'n welcome to have at 'em. I'm experimenting here, as I've repeatedly said from the get-go, and I welcome any and all sincere input. But I'm afraid you're up against OBJECTIVITY, FACT, and the indisputability of the fundamentals of hard science if you "absolutely positively disagree" with the laws of thermodynamics.

 

No, I won't be debating the difference between theory and the laws of thermodynamics here, nor will you get me to explain the differences between speculation, observation, assumption, evidence, fact, proof, etc. . . (again). Can't make me (BTDT). Seems there's been quite enough difficulty here already getting people who aren't sincerely interested to simply pay attention to what they're responding to and comprehending this stuff at the most basic level. You can look up the laws of thermodynamics. NOTE: Please do yourself a large favor and use something a couple or three giant notches more credible than your default source of truth standards, Wikipedia .

 

UPDATE:

 

I was able to get significant riding time in yesterday with the heat sink installed, and the .015" air gap in the OE plastic holder with filled with thermo-paste.

 

Coupla things:

 

1. Unlike the day before, by intentionally and repeatedly trying, I was able to make it "vapor lock" to the point of not starting after a 15-20 minute heat soak. After another 15-20 minute cool-down, it would resume normal starting and running, per the usual pattern over the last 6+ years without the heat sink and without thermo-paste in the holder. It was a warmer day than the day before, so it would seem this accounts for the difference.

 

2. Though the heat sink makes enough of a difference to make the bike rideable with thermo-paste in the gap, it clearly doesn't provide enough of an effect on the sensor signal to overcome the over-lean condition achieved at full operating temperature brought about by adding the thermo-paste, and some (but by no means all) of the idle and low RPM driveability symptoms experienced without the heat sink returned.

 

NEXT STEP: Wiring the linear taper 500K Ω variable resistor in series with the head temp sensor, as mentioned previously, on a modified version of John A's "direct dial control" method, as posted nearly 2 years ago in this thread. I'll be doing this with the .015" air gap in the OE plastic holder filled with thermo-paste, both with and without the heat sink installed. Since I'm pretty busy lately, it may take me another week, or even longer to get a ROUND TUIT.

 

Will advise (Part VIII).

[Greg Field]

As I said earlier, I had this bike in SoCal last summer, and it was very hot. THrough most of California, temps exceeded 100F. The bike ran perfectly.

[Guest ratchethack]

Can these bikes have a totally different reaction with a brass temp sensor holder when they are at idle at the lights in southern california and Seattle ? Accumalitive heat soak difference. They are maybe both fine at high speed long runs but they show up at standstill ?

Bruce, I b'lieve the differences observed at different ambient temperatures are highly dependent upon the quality of the match of the map you're running to the particular modifications. I've also experienced "just fine" fuel metering at speed, and erratic over-lean symptoms only at idle and low RPM, with both the brass and plastic holders (plastic holder filled with thermo-paste, and brass holder both filled and empty).

 

As I've come to understand by demonstrating it repeatedly over many weeks of testing, if you're running a custom map that used the OE head temp sensor without thermo-paste to create that map, changing that OE sensor by adding thermo-paste and/or going to a brass holder WILL send an entirely different set of signals to the ECU, with at least some potential for unwanted results, as is the case with my setup.

 

As noted above, with the PC III map I'm running, with the brass holder, no combination of filling with a solid slug of lead from interference fit with the sensor tip, to various air gaps down to empty (6+ mm air gap) will allow acceptable idle and low RPM running at full operating temp, same with the OE plastic holder filled with thermo-paste. However, it runs more than acceptably under all conditions and temperatures with my current PC III map and the plastic holder with .015" air gap (no thermo paste).

 

But as always, YMMV.

[Greg Field]

Ratch:

 

Consider the possibility that you are chasing a solution to a problem caused by something other than the temp sensor.

 

And why in the first place did you add paste to your sensor or change to a brass one? The whole point of adding the brass sensor or adding a thermally conductive medium to the plastic sensor is to correct a pre-existing condition, the most common one being poor fuel mileage. That's why I did mine. If you don't have a pre-existing condition, why would you bother to make the change?

 

As for the heat sink idea, I believe your analysis is 180-out. I could be wrong, but here's what I see happening in the system:

 

The cylinder head supplies all the heat.

 

The sensor holder is directly connected to the head by the threads of a highly conductive copper insert (the plastic holder) or of a nearly-as-highly-conductive brass holder screwed into the head. Its main purpose is to transfer an accurate reading of the temperature of the head casting to the tip of the sensor. Its secondary purpose is to adapt the sensor to fit the available space.

 

The sensor is an entirely passive device as far as transfer of heat. It can only pick up what the sensor transfers to it. If it is in direct contact, it can get an accurate reading. If it is not in direct contact, it won't necessarily get and accurate reading.

 

The plastic holder has little mass. It has just enough of a copper tip to have adequate strength of threading into the head and to transfer heat to the sensor tip. This makes it close to being the optimal design for serving the sensor's needs. Unfortunately, it isn't very strong and usually crumbles when being removed.

 

The brass holder has considerable mass. It also has fins on its o.d. It IS a heat sink, a pretty optimal one, actually. It was used starting with the first Daytona and then only on the 4-valvers. The Sport 1100s and Calis of the day had a different sensor on the valve cover. Then, starting with the Quota ES and then the Jackal, Calis and V11 Sport, Guzzi switched to the plastic holder. This could have been for reasons of cost, but the retail price of the plastic holder is almost exactly the same as for the brass holder, so there is some evidence that cost is not the reason.

 

What else might be the reason, then? I believe it was because the brass holder is too much of a heat sink. That's why I recommend insulating them, so the temp reading might read more true.

[dlaing]

Being thermally connected, as the engine warms up, the sensor body will draw heat off the probe until the body warms up to the same temp as the probe. Conversely, (this is where the fuel analogy isn't all that appropriate) the relatively massive sensor body will flow heat back into the probe when the probe cools.

The second sentence is nonsense.

First of all, while heat radiates in all directions, it only "flows" or transfers in the direction of high temperature to low temperature.

Under all riding conditions and when cooling the engine off, the heat at the probe will ALWAYS be higher than at the sensor body, and thus the heat will ALWAYS flow from sensor tip to sensor body. The engine is a much bigger heat sink than the sensor.

 

No doubt, adding your heat sink will reduce the temperature at the probe tip and more so at the sensor body, and that is why you are seeing some benefits, but not without the trade off of increased weather induced cooling of the sensor reading.

 

When the Guzzi engineers specified the brass adapter with cooling fins, they were thinking somewhat along the same lines as you, and you have possibly improved upon it by moving the radiator fins to more greatly effect the sensor body temperature, more so than the sensor probe tip.

The only problem I see with your modification is the weather/speed induced variation. Of course running a little rich is the least of your worries when blasting down the interstate at 70MPH in the rain.

 

I think your design could be improved on if the cooling fins were in direct contact with the sensor body, but not the brass adapter, possibly by use of a fiber washer, and shielding the cooling fins from the wind, or maybe getting rid of the cooling fins on adapter.

All just ideas, not absolute truths like the heat transfer direction. <_>

I'll stick to the idea of teflon tape between sensor and brass adapter, possibly insulating the adapter as Greg suggests, continuing to add conductive grease between probe tip and adapter, AND modifying the map.

[Guzzi2Go]

So, while ratchet is scheming on how to use effects of global warming to his advantage, let me try with more down to earth stuff. By far not so "scientific" as ratchet's interpretation of the laws of thermodynamics. Simple arithmetics (four basic operations) will do. English will be simpler too. Furthermore, and unlike ratchet, I am encouraging comments regardless of their "scientific" value or "sincerity". Smoke them if you got them.

 

Let us try to see how adding a resistor in series to oil temp sensor may affect the fuel map. The objective of the exercise to is show what resistor values one may consider (is it 500k or less?). Observe the following table:

 

Explanation

Rn - nominal resistance of the WTS05 sensor straight out of the data sheet. Looking at the table under Temp(20°C) you can read that sensor outputs 3750 ohm

Davg - resistance amidst two adjacent temperature points. For the sake of argumentation, anything between 7860 and 4860 ohm would be treated as 10°C, 4860 to 3085 ohm as 20°C, and so on...

%err - these lines are there to confuse you. Ignore them. The only relevant figure there is the additional resistor value in the 0°C column. Three values are used in this example: 220, 470 and 1k ohm.

 

RGB colored lines are the relevant lines. The values in them represent total resistance = sensor + resistor

 

Green colored values tell you at which temperatures additional resistor has no effect on the temperature reading. For example, at 10°C your bike would be running stock map.

Yellow colored values tell you where temperature readings are affected by the additional resistor. Here your bike would be running richer.

Red colored values tell you where temperature stops affecting the map. The additional resistor takes over completely and the map is cut off. That would be similar to the map published on the Cliff's myECU page, which just stops adjusting anything beyond 40°C. By selecting proper resistor value you can decide where this point may be.

 

Examples:

With R=1k map would be cut off at 50°C, a tad rich between 30-50°C and stock bellow 30°C.

With R=470 ohm map would be cut off at 70°C, a tad rich between 50-70°C, and stock bellow 50°C

With R=220 ohm map would be cut off at 100°C, a tad rich between 60-90°C and stock bellow 60°C

 

Conclusion

Which resistor values make sense? I'd say anything up to whereabouts of 1kohm. 500k certainly not and that is because the sensor is rated 100k@-40°C. With 500k additional resistor one would venture into quite cold areas.

[Guest ratchethack]

. . .[sigh]. . . <-- That was the kinda sigh that only comes outta the depths o' another Winter of our apparent Guzzi community discontent. . .

 

Who knew then, back in June of '07, just how prophetic these words to Pete R. would later be, or that they'd be coming around to ME in the same thread a year and a half later -- or how many times -- ? I assure you, not I. . .

 

. . .seems that people who actually think about things and do experiments to achieve a desired out come are often the brunt of someone's ire. I really appreciate the way you press on while I won't even tell most people about some of the things I've done because I would have to argue some pretty basic stuff and teach class and they still scoff and won't believe me, I just don't have the drive to do that anymore and admire that you do and hope you will continue, it inspires me.

. . .and who knew how truly spoken those words^ were then, just as they appear to be today. . .

 

Ratch:

 

Consider the possibility that you are chasing a solution to a problem caused by something other than the temp sensor.

 

And why in the first place did you add paste to your sensor or change to a brass one? The whole point of adding the brass sensor or adding a thermally conductive medium to the plastic sensor is to correct a pre-existing condition, the most common one being poor fuel mileage. That's why I did mine. If you don't have a pre-existing condition, why would you bother to make the change?

Greg, I've covered all of this before many times in this thread, but to repeat (as in, repeat AGAIN):

 

I'm NOT chasing a solution to a problem here, as I've made it very clear to point out, not only up front, but many times throughout my posts since I resurrected this old thread. I'm merely experimenting here. It's Winter, f'er cryin' out loud. Though yesterday was a "stellar" riding day, it's relatively COLD today, especially early, and my perforated Vanson leathers don't do all that well when it's this cold out where I like to ride.

 

(Again) I have no "problem" to solve. (Again) I wouldn't even think about this stuff in better riding weather.

 

(Again) My Guzzi runs better than perfectly satisfactorily with the OE sensor/holder and no thermo-paste, and, though I've already learned enough to encourage further experimentation, if I learn nothing more of value that I can EVER apply to my Guzzi, well then -- I'll happily put away the experimenting, go back to my OE setup without any thermo-goop, and be happy as a clam, possibly in possession of a better understanding of how the cyl head thermo sensor works.

 

(Again) As I think I've already repeated at least three times lately: Of course the ideal way to solve "problems" with mapping that arise from cylinder heat temp monitoring would be to establish as direct a thermal connection between cylinder head and sensor as possible (add thermo-paste), AND THEN CREATE A NEW MAP based on the more accurate temp read.

 

I'm not doing that. Why not? (Again) In my own case, I consider my map as good a match to my setup as I'm possibly ever likely to achieve, unless or until I make engine/intake/exhaust config changes, of which none are planned.

 

So far, I've discovered several principles of operation here that I hadn't been aware of previously, and I reckon I'll discover a few more before I'm done. Who knows? I may learn something that'll allow me to achieve even better mileage with the map I've got now? (Though better than 40+ mpg might be a stretch.) I might discover a way to achieve this by adding thermo paste without loss of idle and low-RPM driveability due to an over-lean condition? (Again) I'm not necessarily "chasing" either outcome -- but you never know. . .

 

Now I'm not about to back off wot I'm posting here, no matter how many don't, can't (or won't) read, nor no matter how many don't, can't (or won't) attempt to comprehend wot they're reading, and no matter how many seem to either take exception to wot I'm doing, nor no matter how many take offense to my candid reply posts to those who challenge the content of my posts who clearly haven't read and/or haven't as much as attempted to comprehend what they're challenging. Frankly, the evident need for repetition here has gone a bit far beyond tiresome for Yours Truly recently.

 

I'm learning stuff here, and I'm not too concerned about posts from those who believe they already know it all. Clearly, despite the formidable knowledge and experience they believe themselves to possess , many of 'em haven't got the foggiest idea about wot's going on here. On the other hand, there seem to be at least a few others hereabouts who might be capable of understanding some of the simple stuff I'm posting about, and who -- heaven forfend! -- might actually be sincerely interested in some of the apparently bizarre and shocking stuff (!!) I'm coming up with. To my knowledge, I b'lieve I'm the first on this Forum to do some of this. Call me and my antics anything you wish.

 

Again -- anyone NOT interested enough to pay any attention is -- AGAIN -- most enthusiastically welcome by Yours Truly to go find something else to do.

 

Now I have a question for you, Greg. Why would you be compelled to throw cold water here by suggesting that my clearly and repeatedly stated objectives with these Winter experiments are something akin to "bolting on square wheels?"

 

Enquiring minds. . .(well, you know). . .

[Greg Field]

I'll admit that I do not read every word of your posts. As I've mentioned before, the longer ones set my eyes to spinning. These were, in general, longer posts. I swear I remember you complaining in one of these posts of a running problem, though, that you attributed to not having an air gap, and naturally assumed that all this experimentation had a purpose, such as to fix that running problem. "Square wheels" is but a metaphor for trying the opposite of what is likely to bring success. Based on the forgoing, I believed that was the course you were on.

[dlaing]

I think it would make more sense to not put the resistor in series, but have it as a complete bypass.

For example, once warmed up one could hit the bypass using maybe a 500 ohm resistor and the engine would always assume to be 70°C.

This could help with fuel efficiency during warm up, and reduce over leaning when hot.

Flip the bypass off to get fuel efficiency crossing the Mojave in 120°F weather as RH does.

A variable resistor would have more possibilities.

I'd suggest using a Harley TPS with a fixable adjuster knob.

I'd have to check, but I think the TPS is the same resistance range as the engine temperature sensor.

Then you would always have a spare TPS with you, too!!!

Get an onboard wide band O2 meter and you could have manual closed loop.