'98 EV temp sensor resistor?

[flower_king001]

  Hi,

 Can someone point me in the right direction for instructions on how to wire in a resistor with a switch that tells the ECU the engine is either hot or cold?

thanks

[Kiwi_Roy]

You need a thermistor, I may still have one. send me your address in a PM

[Murray]

Or a thermocouple really depends on what the ECU is setup to look for.

[Kiwi_Roy]

Or a thermocouple really depends on what the ECU is setup to look for.

I have never seen one looking for a thermocouple, that would require cold junction compensation.

The chart is on page 12
https://dpguzzi.com/efiman.pdf

[AZRider]

I get what you're doing. Iron Mike Dauphney did that on one of his bikes (I think the Cal1100i, which uses the Big Box computer which I think yours also has). He determined what the resistance is when the bike is warm, and used a fixed-value resistor to tell the computer that the bike is warm. He told me he did this because when the computer thinks the bike is cold, it DUMPS fuel to compensate, dropping the mileage into the toilet. On the early injected Californias, the temp sensor is in the left valve cover, a huge aluminum heat sink out in the cold breeze. Mike said he often got temp sensor readings of stone-cold despite his added oil temperature gauge being well into the normal range. I know he's at least partially right because I often saw 30 to the gallon commuting in winter on my '98 EV. And in case you didn't know Iron Mike, you should know he earned his nickname because he rode easily 30,000 miles a year, often in below zero New England weather. He rode more than enough to justify the experiment.

Iron Mike created a circuit with a switch that allowed him to choose between the actual temp sensor or the fixed-value resistor. He would switch over to the fixed-value resistor when the oil temperature reached normal, and switch back if the oil temperature gauge dropped. I can look up the resistor value if you want and draw up the circuit for you, but Iron Mike told me he stopped using it by the end of the first winter he had it. When a guy who has 4 Guzzis with over 250,000 on each one and does all his own servicing tells me he thinks something isn't healthy for a motorcycle, I take his advice to heart.

RIP Mike Dauphiney.

[Kiwi_Roy]

  Hi,

 Can someone point me in the right direction for instructions on how to wire in a resistor with a switch that tells the ECU the engine is either hot or cold?

thanks

Oh, now I see what you are trying to do, thanks AZRider for pointing that out.
Yes you can just pick a value from the chart, of course it won't change as the temperature goes up or down.

I tried something similar with my VII Sport, I fitted a wide band O2 sensor and tried tweaking the TPS Voltage up or down to change the fuel ratio.

[oldbike54]

Oh, now I see what you are trying to do, thanks AZRider for pointing that out.
Yes you can just pick a value from the chart, of course it won't change as the temperature goes up or down.

 A reverse spoofer  I had to sort this out also Roy , basically it is a bodge to solve the poor temp sensor issue  on older injected bikes , right ?

 Dusty

[Kiwi_Roy]

  Hi,

 Can someone point me in the right direction for instructions on how to wire in a resistor with a switch that tells the ECU the engine is either hot or cold?

thanks

I assume you have the large P8 ECU, if so look at the back page of the file I sent. otherwise let us know what ECU you have.
It would be sensor No (7) Oil Temperature, No (10) is in the air box measuring ambient.

Pin 11 is +, pin 29 is the sensor
10C = 6,000 Ohms
50C = 1,000 Ohms
100C = 200 Ohms
125C = 100 Ohms

If you started out assuming 50C or 1000 Ohms then you could just switch a low value in parallel to simulate the high temperature, no need to remove the 1,000 ohms since it has little effect at elevated temperature.

[Wayne Orwig]

I worked on an EV that had that switch and resistor added to manually override the thermistor. It was the modification that made the rounds at the time.
The bike had basically ruined that persons vacation, and had to be towed about 1000 miles.
The switch had failed in the rain, and really screwed with the mixture.

I recommend that you not do it, or at least put in a switch that will only very slightly modify the resistance, and not leave you stranded by the side of the road. The original switch 'plan' would leave you stranded if it failed.

If you are running way too rich or lean, fix it, before adding a mod. The original EV mapping is pretty good if set up right.

As far as I know, the only thing that needs done, is that in cool weather, after a long ride, the sensor still thinks the motor is pretty cold. So it is running slightly rich. Since the thermistor is an NTC type, switching in a slight parallel resistor when hot wouldn't harm much. Those big block valve covers stay too cold out there in the wind, so it doesn't get a great reading.

I would start by using GuzziDiag to get a reading of what the thermistor is reporting when cold, and when hot. Then we can tell you what needs to be done. Switching in a parallel 2k ohm when hot is probably about all that is needed.

[jcctx]

My (somewhat suspect) memory says the parallel resistance value to be used is 1200 ohms???