Interesting Engine Temp Sensor Behavior
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Intermediate
Joined: Sep 2008
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Interesting Engine Temp Sensor Behavior
The Engine Temp Sensor affects the decisions made by the ECM quite a bit. When collecting Vtune data to tune for a new high flow air filter I got some interesting data. Looking at the data revealed that I had engine temperature readings that would change instantaneously from 270 degrees to 95 degrees instantaneously and stay there for many seconds. It would then instantaneously switch back to the real operating temp.
Some observations:
There were no engine codes.
I had been getting some decel pop intermittently. I now attribute this to the engine temp reading being incorrect.
I had also had several instances of the engine flooding during hot start. Looking back, it was obviously the much higher amount of fuel that the ECM sends during a cold start that was flooding the engine. No reoccurances.
I disconnected the ETS connector and reconnected it. As best I can tell, the problem has not reoccurred but it wasn't plainly obvious the first time. It didn't reoccur during the following vTune sessions.
So, is it possible that the ETS is failing? It seems odd that just disconnecting the wiring and reconnecting would solve a failing sensor.
Maybe it is the wiring? But wouldn't a short in the ETS wiring have thrown a code?
Anyway, it is something I will keep an eye on. If this is a normal failure mode, it would be nice to know so I can fix the problem. But, how many people actually know what their ETS is sending. Maybe this happens all the time and people are unaware. I would never have known that the ETS was sending a wrong signal without having the DataMaster software connected.
Some observations:
There were no engine codes.
I had been getting some decel pop intermittently. I now attribute this to the engine temp reading being incorrect.
I had also had several instances of the engine flooding during hot start. Looking back, it was obviously the much higher amount of fuel that the ECM sends during a cold start that was flooding the engine. No reoccurances.
I disconnected the ETS connector and reconnected it. As best I can tell, the problem has not reoccurred but it wasn't plainly obvious the first time. It didn't reoccur during the following vTune sessions.
So, is it possible that the ETS is failing? It seems odd that just disconnecting the wiring and reconnecting would solve a failing sensor.
Maybe it is the wiring? But wouldn't a short in the ETS wiring have thrown a code?
Anyway, it is something I will keep an eye on. If this is a normal failure mode, it would be nice to know so I can fix the problem. But, how many people actually know what their ETS is sending. Maybe this happens all the time and people are unaware. I would never have known that the ETS was sending a wrong signal without having the DataMaster software connected.
Road Warrior
Joined: Nov 2007
Posts: 1,984
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One thing about the Temp sensor, if you can change a spark plug you can change this sensor.
It just screws into a blind hole.
Which kicked my brain into gear. Why don't you unscrew this thing and clean the threads and screw it back in. Might not be a good ground. I use a tiny touch of copper anti-sease.
It just screws into a blind hole.
Which kicked my brain into gear. Why don't you unscrew this thing and clean the threads and screw it back in. Might not be a good ground. I use a tiny touch of copper anti-sease.
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Intermediate
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Thanks for the idea - I'll try that if it acts up again. So far, it hasn't misbehaved since reconnecting it.
It would be interesting to know how the sensor works - I'm guessing it sends a variable voltage signal with the voltage representing a temperature.
It seems odd that it gave a false output. Maybe that is how these fail.
The consequences of a failure could be significant. For example, at 349 Degrees F, my tune takes as much as 8 degrees of timing out of the spark advance. At a false reading of 95 degrees F there is no correction. I've currently got the maximum knock retard set at 8 degrees.
I've not been able to get the TTS folks to show me what the stock map looks like. But, my bike was running in the mid-300 F range before I used MasterTune on it. I was getting significant ping when the engine was hot, and the ETS was most likely working. Big assumption, but assuming that the stock map has a temperature correction factor too, an erroneous ETS similar to what I saw could result in the advance being far too much for the knock retard system to correct. All this with no indiction of an ETS failure on the console.
It would be interesting to know how the sensor works - I'm guessing it sends a variable voltage signal with the voltage representing a temperature.
It seems odd that it gave a false output. Maybe that is how these fail.
The consequences of a failure could be significant. For example, at 349 Degrees F, my tune takes as much as 8 degrees of timing out of the spark advance. At a false reading of 95 degrees F there is no correction. I've currently got the maximum knock retard set at 8 degrees.
I've not been able to get the TTS folks to show me what the stock map looks like. But, my bike was running in the mid-300 F range before I used MasterTune on it. I was getting significant ping when the engine was hot, and the ETS was most likely working. Big assumption, but assuming that the stock map has a temperature correction factor too, an erroneous ETS similar to what I saw could result in the advance being far too much for the knock retard system to correct. All this with no indiction of an ETS failure on the console.
Road Warrior
Joined: Nov 2007
Posts: 1,984
Likes: 7
Speaking of how it works, and this is my understanding.
All the FI sensors, all of them, get a 5 volt signal from the ECM. One way or the other they take this signal and modify it to give a output voltage that the ECM can use to measure what it is looking at.
Generally 0.50-4.5 volts gives cold to hot, or open to close or low to high pressure, whatever.
They are very simple devices. Pretty much just like autos use. Cost about the same.
With most of these things when sorting out a problem, do just like you did at first. Verify connection.
Check the wires.
Then, no help for somebody like me, it will say, "if the sensor is suspect to replace with a known good one" and see.
Works down to the ECM. Which is fairly rare.
All the FI sensors, all of them, get a 5 volt signal from the ECM. One way or the other they take this signal and modify it to give a output voltage that the ECM can use to measure what it is looking at.
Generally 0.50-4.5 volts gives cold to hot, or open to close or low to high pressure, whatever.
They are very simple devices. Pretty much just like autos use. Cost about the same.
With most of these things when sorting out a problem, do just like you did at first. Verify connection.
Check the wires.
Then, no help for somebody like me, it will say, "if the sensor is suspect to replace with a known good one" and see.
Works down to the ECM. Which is fairly rare.
Thread Starter
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Intermediate
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So far, it still seems to be operating properly. So, I'm wondering if the connection may have started to corrode and the light corrosion modified the signal. I'm wondering if it would be appropriate to use some dielectric grease on the connector, or if the grease isn't meant for that level of heat.
Ultimate HDF Member
Joined: Feb 2008
Posts: 7,217
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From: Southern Ohio
Sounds like this sensor may be related to a problem I'm having and it was suggested I check or change the sensor...where is this thing located on a late model softail?
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Grand HDF Member
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Engine temp is essential for proper fuel/air mixing (fuel injector on time) - particularly during cold start when a richer mixture is req'd. Backfiring can be caused by air leaks in the exhaust system allowing a richer mixture to ignite in the pipes.
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Thread Starter
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Intermediate
Joined: Sep 2008
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I'm not sure how you would check the sensor. I wouldn't have had a clue what was going on with mine except for the fact that I had it connected to DataMaster for a tuning session.
Road Warrior
Joined: Nov 2007
Posts: 1,984
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Since it is two wire, doesn't ground thru the engine, you could use a hot plate with a boiling pot on it. (Still make those things???) Boiling water would be 212 at sea level. Whatever where you are at.
Put the end in the water, don't get the whole thing wet. Use Data mode to see the temperature. should be the water temp. could use a thermometer to cross check.
but taking the connection off and puting it back on may be the thing. bad connection.
Put the end in the water, don't get the whole thing wet. Use Data mode to see the temperature. should be the water temp. could use a thermometer to cross check.
but taking the connection off and puting it back on may be the thing. bad connection.