N14 celect plus erratic idle

[schISM]

(08-28-2022 )Luckyjayb Wrote:  I’m getting the correct ambient air pressure though

I’m not familiar with the N14 but the ambient air pressure is only sourced from the barometric pressure sensor(on an ISX). The ambient temperature is a separate source usually provided by the OEM. So you could have correct ambient air pressure and a malfunctioning ambient air temp. circuit.

[Luckyjayb]

(08-28-2022 )SemiSweet Wrote:  I had one hunt at idle and the ambient pressure sensor was the issue. But didn’t move as much rpm as your stating. It was at a default pressure which didn’t change even when unplugging. Not sure if yours is the updated sensor which is much smaller and just zip ties to the harness instead of mounting on a bracket to the block to the right of the ecm. The wiring on those n14s can be terrible as well. Did you check or replace all the injector pass trough connectors and verify the harness plugs were not stretched out causing intermittent connection.

Checked them, ohm’d them, and even tried a new set. It’s a new harness on there but the old style sensor. The sensor is reading the correct barometric pressure but not ambient air temp. The intake air temp and pressure are fine and the coolant sensor is working like it should and is new oem.

[Luckyjayb]

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  I’m getting the correct ambient air pressure though

I’m not familiar with the N14 but the ambient air pressure is only sourced from the barometric pressure sensor(on an ISX). The ambient temperature is a separate source usually provided by the OEM. So you could have correct ambient air pressure and a malfunctioning ambient air temp. circuit.

Yea I know what you mean on them. This is a 99’ KW W900L. No reading in the cab for ambient air temp. This was live data via insite so it has to be picking it up somewhere.

[schISM]

(08-28-2022 )Luckyjayb Wrote:  

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  I’m getting the correct ambient air pressure though

I’m not familiar with the N14 but the ambient air pressure is only sourced from the barometric pressure sensor(on an ISX). The ambient temperature is a separate source usually provided by the OEM. So you could have correct ambient air pressure and a malfunctioning ambient air temp. circuit.

Yea I know what you mean on them. This is a 99’ KW W900L. No reading in the cab for ambient air temp. This was live data via insite so it has to be picking it up somewhere.

Ok, so no data to the cab temp tells me the sensor or circuit for temp has malfunctioned. Insite is just passing along the default value(40 degrees) that the ECM uses if there’s no data being supplied by the sensor. Again this may not be the issue for the erratic idle but if everything else has been checked this would be next on my list.

[Luckyjayb]

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  I’m getting the correct ambient air pressure though

I’m not familiar with the N14 but the ambient air pressure is only sourced from the barometric pressure sensor(on an ISX). The ambient temperature is a separate source usually provided by the OEM. So you could have correct ambient air pressure and a malfunctioning ambient air temp. circuit.

Yea I know what you mean on them. This is a 99’ KW W900L. No reading in the cab for ambient air temp. This was live data via insite so it has to be picking it up somewhere.

Ok, so no data to the cab temp tells me the sensor or circuit for temp has malfunctioned. Insite is just passing along the default value(40 degrees) that the ECM uses if there’s no data being supplied by the sensor. Again this may not be the issue for the erratic idle but if everything else has been checked this would be next on my list.

That’s what I was thinking but it being a 99’ KW W900L it doesn’t have one in the cab and I can’t find one on the parts side on quickserve if there is one on that engine

[Luckyjayb]

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  

(08-28-2022 )schISM Wrote:  

(08-28-2022 )Luckyjayb Wrote:  I’m getting the correct ambient air pressure though

I’m not familiar with the N14 but the ambient air pressure is only sourced from the barometric pressure sensor(on an ISX). The ambient temperature is a separate source usually provided by the OEM. So you could have correct ambient air pressure and a malfunctioning ambient air temp. circuit.

Yea I know what you mean on them. This is a 99’ KW W900L. No reading in the cab for ambient air temp. This was live data via insite so it has to be picking it up somewhere.

Ok, so no data to the cab temp tells me the sensor or circuit for temp has malfunctioned. Insite is just passing along the default value(40 degrees) that the ECM uses if there’s no data being supplied by the sensor. Again this may not be the issue for the erratic idle but if everything else has been checked this would be next on my list.

My thoughts and per Cummins schematics, it shows the ambient air temp sensor is Cummins responsibility.

[schISM]

Had to go reread what you meant by, “No reading in the cab for ambient air temp.” I thought you were saying there “is” a display in the cab but it wasn’t reading anything. No matter though, at this point you can clearly see the circuit for ambient air temp is isolated solely to one sensor. Now find the sensor and unplug it. If your reading in Insite stays at 40 degrees you know the circuit is faulty. Now make sure the circuit has a 5 volt feed, if so you could replace the sensor to see if that’s the issue or ohm out the signal wire to the proper pin on the ECM engine side.