Resistance of Inlet Temperature Sensor?

[Tipover_Bob]

Does anyone know the correct resistance for the inlet air temperature sensor (mounted above the air filter)? I got a reading of 800 K ohms at 50 degrees F.

Tipover Bob

[SoilSampler]

I just checked my 96 GS since I have it apart and the multimeter handy. 3.8K ohms, right or wrong. I didn't see a spec. in my Haynes manual.

[Tipover_Bob]

I just checked my 96 GS since I have it apart and the multimeter handy. 3.8K ohms, right or wrong. I didn't see a spec. in my Haynes manual.

 

SS:

Thanks, I am thinking this may be reason for my bike's hard starting.

Tipover Bob

[RFW]

800 K is WAY too high. These thermistors are usually in the range of 1 to 5 K at 25°C. Note that whatever their normal resistance is at their 25°C rating, it varies STRONGLY (and logarithmically) inversely with temperature. So the only way any comparison of resistance makes any sense at all, is when temperature is taken into account.

 

A high value like 800K will make the motor think it is VERY cold, and a rich mixture will result. You can connect a resistor of around 4.7K in place of the thermistor and see if starting is any easier.

[ShovelStrokeEd]

Hmmmmm. Be careful there multiple Bobs. You might just wind up building your own Techlusion.

[Tipover_Bob]

800 K is WAY too high. These thermistors are usually in the range of 1 to 5 K at 25°C.

 

Thanks Bob, It looks like the bike has been considering the sensor out of range and defaulting to a fixed temperature. That probably accounts for the slow (hard - takes three or more tries) cold start.

Tipover Bob

[Clive Liddell]

Bob, I think your sensor is not WAY out, see below:

===========

From a post back in 1998, some of which Rob Lentini supplied:

 

>O degrees C should be 5.5K ohms (freezing)

>7.2 degree C is 4.5K ohms.. (observed)

>20 degrees C should be 2.5K ohms

>40 degrees C should be 1.25K ohms

>60 degrees C should be 600 ohms

>80 degrees C should be 320 ohms

>100 degrees C should be 190 ohms (boiling)

and I will add a couple more points:

120C approx 112,7 ohms

140C approx 71,2 ohms

======================

 

So 50F is 10C and around 3K ohm. I would suggest to try and raise the temperature a couple of steps taking readings. Also get a second opinion by trying another multimeter.

 

[Boffin]

Bob, I think your sensor is not WAY out, see below:

===========

From a post back in 1998, some of which Rob Lentini supplied:

 

>O degrees C should be 5.5K ohms (freezing)

>7.2 degree C is 4.5K ohms.. (observed)

>20 degrees C should be 2.5K ohms

>40 degrees C should be 1.25K ohms

>60 degrees C should be 600 ohms

>80 degrees C should be 320 ohms

>100 degrees C should be 190 ohms (boiling)

and I will add a couple more points:

120C approx 112,7 ohms

140C approx 71,2 ohms

======================

 

So 50F is 10C and around 3K ohm. I would suggest to try and raise the temperature a couple of steps taking readings. Also get a second opinion by trying another multimeter.

 

SO if freezing is 5.5Kohm, decreasing with a increase in temperatrure, 800Kohm is too damn cold for me... and way out of range.

 

Andy

[Tipover_Bob]

I have ordered a replacement from Beemer Bone Yard and am looking forward to seeing if there is a difference. I understand I can add some resistance to the "new" air temperature sensor by inserting a 1k potentiometer or a 500/1000 ohm resistance which will change either the spark advance or the mixture. But first I want to see if I can cure the hard starting.

Tipover Bob

[RPG]

don't forget the Oil temp sensor when diagnosing the hard starting problem.

 

rpg

[Tipover_Bob]

don't forget the Oil temp sensor when diagnosing the hard starting problem.

 

Rick: I had started out with the oil temperature sensor a week or two ago but I ran into a problem trying to pull the connector. It just wouldn't let go of the sensor. I decided to leave it alone rather than possibly break the sensor or its connector.

However, after checking the air intake sensor, which is easy to get to and its connector is easy to remove, and finding its resistance to be on the order of 800,000 ohms; I believe I have a winner.

Tipover Bob

[RFW]

Hmmmmm. Be careful there multiple Bobs. You might just wind up building your own Techlusion.

Worse yet, there are multiple "Bob Wilsons" as well. I hasten to point out that I am NOT the Bob Wilson who won the Nobel Prize in physics in the early '80s for discovering the microwave background radiation of the universe, nor am I the Bob Wilson who worked with Richard Feynmann on the atomic bomb in the 1940s. Also, contrary to what some of my German friends think, I am not the Bob Wilson who is a Wagnerian stage director in Berlin either (in fact, I barely can even spell "Nibelungenring"!).

 

Worse yet, there are even two of us here at work with the same damned name! Sigh! I think I need to change my name.

[Tipover_Bob]

don't forget the Oil temp sensor when diagnosing the hard starting problem.

 

Rick:

Well dang my doggies, you may be right. I got my replacement air temperature sensor today from Beemer Bone Yard. I checked its resistance and it was right on at 2,000 ohms. So I pulled the old sensor out and checked its resistance one more time, 2,000 ohms. What the? I checked it to start with and it was 800,000 ohms. Anyway, to make a long story short, I had to use two jumper cables with alligator clips to check the resistance of the old air temperature sensor in place on the bike. Amazingly, one of the jumpers with alligator clips had a 600,000 ohm resistor in line on it under the rubber insulator. I guess it was there on purpose, but I'll be danged if I knew it from the years that I had had it. Boy do I feel stupid. But at least the replacement turn signal flasher cured my fast blinking turn signals. So all is not lost. However, the bike is still hard starting. I may go for that oil temperature sensor and measure its resistance without the said jumper if I can figure how to remove the clip from the sensor.

Tipover Bob

[big-t]

I had started out with the oil temperature sensor a week or two ago but I ran into a problem trying to pull the connector. It just wouldn't let go of the sensor. I decided to leave it alone rather than possibly break the sensor or its connector.

 

 

I may go for that oil temperature sensor and measure its resistance without the said jumper if I can figure how to remove the clip from the sensor.

 

 

If I remember correctly the oil temp sensor has a boot on the top of it, but its really made with a pigtale that does not disconnect from the sensor.Got to follow the wires back to the connector and take it apart.

[Tipover_Bob]

If I remember correctly the oil temp sensor has a boot on the top of it, but its really made with a pigtale that does not disconnect from the sensor.Got to follow the wires back to the connector and take it apart.

 

Big-T:

Thanks, I'll try that.

Tipover Bob