Squirley Coolant temp

[Nitro Nick]

Check the actual sensor. There are 2 coolant temp sensors. You want to check the one with 2 wires as your single wire is working right. Check the resistance between the two pins right on the sensor when the car is cold and again when its hot. Post the values here...should be similar to the values posted before. If they come out right we can unplug the megasquirt ecu and plug the sensor back in and probe the ecu harness pins to make sure the same values are reaching the ecu. Lmk what you find or if you need me to explain any of the steps further.

I'm not too familiar with how to go about testing this. Im guessing you would use a multimeter and post the numbers. assuming the sensor is good do you know which pins on the harness are for this sensor on the ecu to test? This is really messing with the car because it assumes the car is only at 70 degrees F and in a warmup loop...

[kyleconstantine]

Check the actual sensor. There are 2 coolant temp sensors. You want to check the one with 2 wires as your single wire is working right. Check the resistance between the two pins right on the sensor when the car is cold and again when its hot. Post the values here...should be similar to the values posted before. If they come out right we can unplug the megasquirt ecu and plug the sensor back in and probe the ecu harness pins to make sure the same values are reaching the ecu. Lmk what you find or if you need me to explain any of the steps further.

[nando]

Sensor could be bad, or it could be the wrong sensor, or the bias resistor could be wrong. I've been using the settings in the drop down for years without issue.

[Nitro Nick]

there's been a drop down in the menu of Tuner Studio for the E30 sensor for almost 10 years now. You don't need to manually enter them in. ;)

also the IAT settings will depend on what IAT you are using. Since you can literally use anything, don't just take random settings off the internet. Find the sensor you have, and use the settings specific to it. Many people have used the GM sensor and it's already got a calibration in the Tuner Studio menu. Use that.

I'm having a bit of trouble with this...any ideas?

[Nitro Nick]

there's been a drop down in the menu of Tuner Studio for the E30 sensor for almost 10 years now. You don't need to manually enter them in. ;)

also the IAT settings will depend on what IAT you are using. Since you can literally use anything, don't just take random settings off the internet. Find the sensor you have, and use the settings specific to it. Many people have used the GM sensor and it's already got a calibration in the Tuner Studio menu. Use that.

So the other day I took the e30 out for a ride. It had been out once during the winter when it was nice but yesterday was the first real time I took it out to mess around with the idle. I had replaced the Coolant temp sensor in hopes that it was the culprit. However even with a new CLT sensor the readings were still off. The gauge that I pull up in tuner studio says it only reaches about 60 degrees when warmed up. And I feel like this has to do with my idle issues as well. Basically I think its telling the PNP that my car isn't warming up when the gauge in the cluster is pegged right in the middle where its supposed to be. I tried re writing to the controller using the calibration drop down menu and selecting the e30 325i CLT and it didn't help.

I tried emailing whodwho but I know he is a hard guy to get a hold of.

Anyone have any ideas?

[varg]

kyleconstantine is right, there are two sensors. Your sensor is probably bad. With the engine warmed up unplug the sensor and probe the sensor's pins with a multimeter, if the resistance is over 400Ω the sensor is bad.

[kyleconstantine]

I believe there are 2 seperate cts. One is a 1 wire that goes to the cluster. The other is a 2 wire that goes to the ecu/megasquirt.

[Nitro Nick]

Lifted from the DIYautotune site... I use these values with no problems.

It's been a couple years, but IIRC, there's a common sensors dropdown where you can select BMW 325 or something like that and it will prepopulate the curve with these same values.

For the CLT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’.

Now you’ll do the same for the IAT. Select ‘Intake Temperature Sensor’ at the top in the drop down box. (NOTE – If you are removing your MAF/AFM as a part of the DIYPNP installation process, do not recalibrate your IAT Sensor now)

For the IAT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’. Now click Close to Exit.

Still did not qork. Any other ideas? Faulty cts? I don't think it's Faulty because my stock gauge works fine...

Sent from my SM-G935V using Tapatalk

[Nitro Nick]

Lifted from the DIYautotune site... I use these values with no problems.

It's been a couple years, but IIRC, there's a common sensors dropdown where you can select BMW 325 or something like that and it will prepopulate the curve with these same values.

For the CLT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’.

Now you’ll do the same for the IAT. Select ‘Intake Temperature Sensor’ at the top in the drop down box. (NOTE – If you are removing your MAF/AFM as a part of the DIYPNP installation process, do not recalibrate your IAT Sensor now)

For the IAT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’. Now click Close to Exit.

I tried doing this yesterday and it did not correct the problem...any other ideas of troubleshooting?

Anyone?

Sent from my SM-G935V using Tapatalk

[nando]

there's been a drop down in the menu of Tuner Studio for the E30 sensor for almost 10 years now. You don't need to manually enter them in. ;)

also the IAT settings will depend on what IAT you are using. Since you can literally use anything, don't just take random settings off the internet. Find the sensor you have, and use the settings specific to it. Many people have used the GM sensor and it's already got a calibration in the Tuner Studio menu. Use that.

[Nitro Nick]

Lifted from the DIYautotune site... I use these values with no problems.

It's been a couple years, but IIRC, there's a common sensors dropdown where you can select BMW 325 or something like that and it will prepopulate the curve with these same values.

For the CLT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’.

Now you’ll do the same for the IAT. Select ‘Intake Temperature Sensor’ at the top in the drop down box. (NOTE – If you are removing your MAF/AFM as a part of the DIYPNP installation process, do not recalibrate your IAT Sensor now)

For the IAT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’. Now click Close to Exit.

Ok i found the other day the drop down for the bmw 325. and hopefully that works. I haven't had a chance to check how accurate it really is since the gauge cluster is just a needle with no number readings.

Also, as far as the IAT sensor goes. I wired in a GM sensor to the existing wires from the MAF sensor which was removed. Do I go along with this calibration process you listed. It is the standard gm IAT sensor that is recommended for megasquirt and I welded a bung in my intercooler piping about 8 inches from my throttle body. Let me know because i saw your note about the IAT sensor and it was slightly confusing.

Thanks for the help.

[keyland]

Lifted from the DIYautotune site... I use these values with no problems.

It's been a couple years, but IIRC, there's a common sensors dropdown where you can select BMW 325 or something like that and it will prepopulate the curve with these same values.

For the CLT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’.

Now you’ll do the same for the IAT. Select ‘Intake Temperature Sensor’ at the top in the drop down box. (NOTE – If you are removing your MAF/AFM as a part of the DIYPNP installation process, do not recalibrate your IAT Sensor now)

For the IAT, use the following table with a bias resistor setting of 2490 ohms:

Temperature F / C     Resistance In Ohms
14 / -10                  9500
68 / 20                   2500
176 / 80                  330

Enter these values, and click ‘Write to Controller’. Now click Close to Exit.

[Nitro Nick]

Did you tell the MS which coolant temp sensor you are using? There should specifically be a Bosch E30 option, or something very similar. There is a calibration curve for every sensor and if it's not set properly it can mess with your readings. If it's working in the dash, it's definitely an MS config problem.

In Tuner Studio, top left corner:

"Tools" > "Calibrate Thermistor Tables"

Could you screen shot me your calibration curve? I cant seem to figure it out.

[Nitro Nick]

Did you tell the MS which coolant temp sensor you are using? There should specifically be a Bosch E30 option, or something very similar. There is a calibration curve for every sensor and if it's not set properly it can mess with your readings. If it's working in the dash, it's definitely an MS config problem.

In Tuner Studio, top left corner:

"Tools" > "Calibrate Thermistor Tables"

Been MIA for a bit. I will check this out. I definitely did not know about that setting and will try it out later. Thanks!

[CorvallisBMW]

^yup, what he said