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mmc205

Crank case pressure sensor atmospheric reading (19 TPI 300)

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2 minutes ago, Doc Brown said:

Do you have any info where the second one is located and why it needs two of them?

I'm not sure where it's located. Somewhere around the oil tank, I think.

The reason for the 2nd one is to eliminate the need to stop and restart the bike every 3K' of gained or lost altitude like you have to do with the 18/19's, since the CCP sensor has to do double duty in those bikes. Now they have separate sensors for the crank case pressure and for baro pressure. Same exact sensor.

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Thank you jeb, yes that sounds plausible, so one of them isn't a crank case sensor literally, it is an ambient pressure sensor.

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On 11/16/2020 at 5:45 AM, mmc205 said:

Hey all, wondering if anyone has hooked up to their bike with a ECU reader and checked the pressure sensor reading on either the atmospheric sensor (20+ bikes) or disconnected the crank case pressure sensor (CPS) tube that runs to the crank case and let it read atmospheric.  If so what reading do you get?  Close to atmospheric (14.7)?

With the bike at idle, the CPS reads 13.3-13.78 psi, which seems roughly correct compared to some other folks readings.

But when I disconnect the CPS tube and its vented to atmosphere, I get 13.78, which is almost 1 psi different than atmospheric pressure of about 14.7 +/- 0.2 depending on conditions that day.  I'm having some running issues and think the CPS may be to blame.

 

Thanks in advance.

I think some folks on ktmtalk tried this - the output you see on a obdii tool is a calculated value from the ECU, not a direct reading from the CCPS. It doesn't seem to be a good way to diagnose CCPS issues. Not to mention, on your '19, there's only one CCPS, so when the engine is running, it cannot detect ambient air pressure at all - the ECU is using a stored value from the last time the engine was shut down.

Also worth mentioning - the CCPS has to measure a transient pressure that is changing many times per second, and outputs a voltage of 0v-5v to the ECU, which then interprets this signal. We're not sure yet what the exact failure mode is, when the CCPS does go bad. They may still read/measure ambient pressure just fine, but maybe a failed sensor cannot keep up w/ the transient nature of crankcase pressures, hence the failure. 

If you suspect the sensor is the culprit at all, it's probably worth just ordering a new one and swapping it in. If nothing changes, then at least you have a spare sensor. 

Edited by jrodicus100

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I'm using the free Torque lite app...looks like I'm getting data.

I see something called Barometric Pressure and Intake Manifold Pressure?

I'm idling at about 2500ft altitude and they say:

Baro=13.1 psi and steady Intake=12.6 psi and varying

Edited by SlowDinoDog

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On 11/18/2020 at 9:36 PM, jrodicus100 said:

Also worth mentioning - the CCPS has to measure a transient pressure that is changing many times per second, and outputs a voltage of 0v-5v to the ECU, which then interprets this signal. We're not sure yet what the exact failure mode is, when the CCPS does go bad. They may still read/measure ambient pressure just fine, but maybe a failed sensor cannot keep up w/ the transient nature of crankcase pressures, hence the failure. 

If you suspect the sensor is the culprit at all, it's probably worth just ordering a new one and swapping it in. If nothing changes, then at least you have a spare sensor. 

I have to agree here. My bike ran mint for the first 10hrs or so. After that the dreaded 1/4 throttle stutter joined the party. I found a video online that you could swop your ambient and ccps sensor as an initial test. Which I did and the stutter was resolved for about 5hrs. Before ordering a new sensor I wanted to gather as much data as I could. So I bought the LonElec cable from the UK and had the bluetooth OBD2 adapter. Using the Torque app from the andriod play store I could see the intake manifold pressure jump between 13.7psi - 14.4 psi @idle - which I believe is fine as pressures in a 2t vary. Next step is to datalog the bike and posting the data to datazap.me for graphical representation.

 

Then I moved onto testing the sensors with a multimeter by following the below procedure(plain MAP sensor testing procedure).

 

I tested my CCPS with a multimeter while the bike was running.

Bike: KTM 300 XC-W 2020 TPI (less than 25hrs).

@Sea level and 25C ambient temp.

CCPS readings with the bike warmed up were:

  • Reference voltage: 4.99V at the sensor
  • Ground was fine
  • Signal voltage: 2.20V at idle 

Ambient sensor readings with the bike warmed up were:

  • Reference voltage: 4.99V at the sensor
  • Ground was fine
  • Signal voltage: 2.35V at idle 

 

image.png.1cdaa7c6583243a9dc78b573090d4363.png 

image.png.89a270516aa5680b10d79e3f13d7c065.png

As @jrodicus100 stated, the sensor output reading could be there, but the sensor for some reason are still faulty. Having sensor outputs doesn't mean its in working order. I also read online that a pressure washer could be damaging the sensors in some way - not sure how true that is.

Edited by shablamy

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3 hours ago, shablamy said:

I have to agree here. My bike ran mint for the first 10hrs or so. After that the dreaded 1/4 throttle stutter joined the party. I found a video online that you could swop your ambient and ccps sensor as an initial test. Which I did and the stutter was resolved for about 5hrs. Before ordering a new sensor I wanted to gather as much data as I could. So I bought the LonElec cable from the UK and had the bluetooth OBD2 adapter. Using the Torque app from the andriod play store I could see the intake manifold pressure jump between 13.7psi - 14.4 psi @idle - which I believe is fine as pressures in a 2t vary. Next step is to datalog the bike and posting the data to datazap.me for graphical representation.

 

Then I moved onto testing the sensors with a multimeter by following the below procedure(plain MAP sensor testing procedure).

 

I tested my CCPS with a multimeter while the bike was running.

Bike: KTM 300 XC-W 2020 TPI (less than 25hrs).

@Sea level and 25C ambient temp.

CCPS readings with the bike warmed up were:

  • Reference voltage: 4.99V at the sensor
  • Ground was fine
  • Signal voltage: 2.20V at idle 

Ambient sensor readings with the bike warmed up were:

  • Reference voltage: 4.99V at the sensor
  • Ground was fine
  • Signal voltage: 2.35V at idle 

 

image.png.1cdaa7c6583243a9dc78b573090d4363.png 

image.png.89a270516aa5680b10d79e3f13d7c065.png

As @jrodicus100 stated, the sensor output reading could be there, but the sensor for some reason are still faulty. Having sensor outputs doesn't mean its in working order. I also read online that a pressure washer could be damaging the sensors in some way - not sure how true that is.

Excellent info! Working order of sensors can be checked by hooking up both the CCP and Baro. sensors to a common pressure source. Sensors can be hooked together with plastic tee and tubing and pressure can be introduced with a small hand pump or by mouth. Two multimeters would be ideal. Voltages should track each other throughout entire sensor pressure range  Tygon tubing and tees readily available at any medical supply store. These appear to be absolute pressure sensors so will read approx. 2.5 v at normal atmospheric pressure of 100kpa and I expect will read 0v when -100kpa applied and 5v when 100kpa pressure applied.

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I still wonder if starting the bike with the exhaust plug in the silencer after washing takes out the sensor.  Any chance you washed it and forgot to remove the plug?

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