Disc I ....starting problem

[seamaster]

Hi All..I am the proud owner of 96 Disc I. Love it! I have been trying to trouble shoot why it will start..no problem. But, when I park it and return a short time later it will turn over fine but won't start. If I let it sit for a little while it will start. I ask a friend check the codes from the engine and all I am getting is an overheated engine code. Strange, because the engine temp gauge is not showing any overheating. I'm baffled...anyone have an idea.

[Savannah Buzz]

1. What is the code number?

2. You have a classic complaint that goes with a bad Crank Position Sensor. You can test the theory by pouring cold water on it next time. The sensor is a reluctor style that has a tip inserted to within about 2mm of the flywheel. It produces pulses that tell the ECU when to make sparks happen.

Page attached from RAVE shop manual.

[Spike555]

Bad fuel temp sensor.
Your check the code again, I am betting it is a "fuel temp out of range" code.
Drivers side fuel rail, 5 min to replace.
Land Rover Troubleshooting - Hot Start Problems

[seamaster]

I was talking to a friend and he mentioned a sensor that could be causing te problem....the heat sensor beside the temp sensor near the thermostat...I guess this won't let the engine run when overheated...I didn't write the code # when I had the chance. Thoughts?

[Savannah Buzz]

I believe your friend was talking about the coolant temp sensor. There are two vertical sensors to the side of the thermostat. The one with a single wire drives the heat gauge. The one with a square top and two wires drives the ECU. If it is unplugged, it makes the engine think it is -40F and you need more fuel. These are in the top right pix attached.


Here is pix of where the other one is. It is X128 in the bottom left pix. It measures engine fuel temp, and is normally associated with problems dealing with hot starts. It basically tells the ECU to run a little more fuelto get the vapor lock bubbles out of the injection system. I would suppose if it is wierd this time of year (cold in North America) that it could do other things.


Also attached is color pix of both gauge and coolant temp sensors, coolant on right.

From the RAVE:

Engine coolant temperature sensor (ECT Sensor)
This sensor consists of a temperature dependant
resistive metal strip. The resistance of the strip varies
considerably with coolant temperature, i.e. from 28K

ohms at - 30

°C to 90 ohms at 130°C, and 300 Ohms

at 85

°C. The ECT Sensor signal is vital to engine

running, as the correct fuelling is dependant upon
engine temperature i.e. richer mixture at low
temperatures. If the sensor is disconnected or failure
occurs a default value will be supplied to the system.
The initial default value selected will be based on the
value of the air intake temperature. This will increase
to a nominal warmed up value over an individual time,
programmed for each default value. The fault may not
be evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.

AND

Engine fuel temperature sensor (EFT Sensor)
This is another resistive sensor. Located on the fuel
rail it measures temperature of the rail rather than the
fuel. The resistance varies with changes in
temperature. The signal is used to increase the
injection pulse time when undergoing hot restarts.
When the fuel is hot, vapourisation occurs in the rail
and bubbles can occur in the injectors. Increasing the
pulse time flushes the bubbles away, and cools the
fuel rail with fuel from the tank. The fault may not be
evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.

I know that on my cheap scanner the coolant temp shows up as a reading, but fuel temp does not. This is not the same as the temp gauge, which uses another sensor. If you don't have a scanner, your local parts store could read it for you. A sensible coolant temp sensor reading (like 195 - 208F) in their parking lot may point toward the fuel temp sensor. Unplug the coolant temp sensor and the heat gauge won't change but the scanner will show something like -40F. A bad coolant sensor usually makes other things show up, like running rich, high idle. But the RAVE says hot start problems could also be this.

[Spike555]

Originally Posted by seamaster

I was talking to a friend and he mentioned a sensor that could be causing te problem....the heat sensor beside the temp sensor near the thermostat...I guess this won't let the engine run when overheated...I didn't write the code # when I had the chance. Thoughts?

Yes it is a sensor causing the problem.
No there is no sensor that will shut off the engine if it gets to hot, the engine will just melt itself.
Same thing with the oil pressure, the engine will run until it seizes.

[Savannah Buzz]

Not by design, but the crank position sensor has a nasty habit of doing that, even though it is not designed as a safety system.