FUEL TEMPERATURE SENSOR
Discussion
Hello again!
In an earlier thread regarding the cold start behaviour of my car, one question raised was about the fuel temperature sensor.
It is definitely fitted and connected on my car but does it do anything? On page 87 of the Steve Heath book it says that they are commonly unused and indeed there is an "unused" one for sale on ebay that was removed from a Chimaera!
Is there a definitive answer to this one and if it is not used in our application what was it supposed to do? The cold running must surely be influenced by this?
Regards Chris.
In an earlier thread regarding the cold start behaviour of my car, one question raised was about the fuel temperature sensor.
It is definitely fitted and connected on my car but does it do anything? On page 87 of the Steve Heath book it says that they are commonly unused and indeed there is an "unused" one for sale on ebay that was removed from a Chimaera!
Is there a definitive answer to this one and if it is not used in our application what was it supposed to do? The cold running must surely be influenced by this?
Regards Chris.
Hi Chris,
Yes, the fuel temp value is definitely used by the 14CUX system. Land Rover said this about the sensor:
Engine Fuel Temperature Sensor (EFTS)
The fuel temperature sensor, mounted on the fuel rail, operates in the same manner as the
ECTS. When the ECM receives a high fuel temperature input, it increases injector pulse during
hot restarts. When fuel is hot, vaporization occurs in the fuel rail and bubbles may be found in
the injectors. This can lead to hard starting. Increasing injector pulse time flushes the bubbles
away and cools the fuel rail with fresh fuel from the tank. Since 1989, the EFTS has also been
used by ECM to trigger operation of the radiator fans when under-hood temperatures become
extreme.
As with the engine coolant temperature sensor, a diagnostic trouble code (15 [14CUX only]) is
stored when the signal is out of range (0.08V to 4.9V) for longer than 160 milliseconds. No
default value is provided by the ECM, however the MIL will illuminate.
It only appears unused in a TVR for two reasons. First, unlike the coolant temp sensor, it is only a minor input to the fuel adjustment (adjusting for fuel density only). Second, the fault code created when it's unplugged does not illuminate the MIL since the MIL is disabled in TVRs. Also, when unplugged, a mid-point default value is used which is, under most conditions, reasonably close to the actual temperature.
When this sensor is unplugged, the secondary hot-starting feature is also lost.
Yes, the fuel temp value is definitely used by the 14CUX system. Land Rover said this about the sensor:
Engine Fuel Temperature Sensor (EFTS)
The fuel temperature sensor, mounted on the fuel rail, operates in the same manner as the
ECTS. When the ECM receives a high fuel temperature input, it increases injector pulse during
hot restarts. When fuel is hot, vaporization occurs in the fuel rail and bubbles may be found in
the injectors. This can lead to hard starting. Increasing injector pulse time flushes the bubbles
away and cools the fuel rail with fresh fuel from the tank. Since 1989, the EFTS has also been
used by ECM to trigger operation of the radiator fans when under-hood temperatures become
extreme.
As with the engine coolant temperature sensor, a diagnostic trouble code (15 [14CUX only]) is
stored when the signal is out of range (0.08V to 4.9V) for longer than 160 milliseconds. No
default value is provided by the ECM, however the MIL will illuminate.
It only appears unused in a TVR for two reasons. First, unlike the coolant temp sensor, it is only a minor input to the fuel adjustment (adjusting for fuel density only). Second, the fault code created when it's unplugged does not illuminate the MIL since the MIL is disabled in TVRs. Also, when unplugged, a mid-point default value is used which is, under most conditions, reasonably close to the actual temperature.
When this sensor is unplugged, the secondary hot-starting feature is also lost.
Thanks for the info.
I think I will need to get the car plugged in and see if there are any fault codes present.
A little research suggests LUCAS SNB803 to be the correct sensor. On ebay they are over £130! surely this can't be right? It looks the same as the CTS but without the probe on it.
Would a dud sensor affect the cold running of the engine or is that a silly question? Sorry!
The mystery deepens.
Regards Chris.
I think I will need to get the car plugged in and see if there are any fault codes present.
A little research suggests LUCAS SNB803 to be the correct sensor. On ebay they are over £130! surely this can't be right? It looks the same as the CTS but without the probe on it.
Would a dud sensor affect the cold running of the engine or is that a silly question? Sorry!
The mystery deepens.
Regards Chris.
danbourassa said:
It only appears unused in a TVR for two reasons. First, unlike the coolant temp sensor, it is only a minor input to the fuel adjustment (adjusting for fuel density only). Second, the fault code created when it's unplugged does not illuminate the MIL since the MIL is disabled in TVRs.
The MIL light certainly worked on mine when it had the 14CUX, both pre and post Mark Adams treatment Gassing Station | Chimaera | Top of Page | What's New | My Stuff