RRC 3.9 Temperature sensor problem

Looking for a bit of direction here.

My RRC 3.9 is giving me a little bit of hot starting grief. If it doesn't catch first time when starting hot you could be sitting there for half an hour with it feeling like its flooded. It also seems to run better cold than hot.

Now I hooked it up to Rovacom for the 14cux and noticed that the coolant temp was not showing the correct temp or even changing at all, stuck at 34 deg. Ahhh I said, that makes sense, I've heard of that before, it still on the cold fuel map. Right I'll replace the temp sender and problem sorted
Went to britishv8.org and yeah theres the sensor, I'll replace that, great. Changed sensor and guess what no change

Back on to RAVE, looked up MFi and fook me its showing me a different sensor on the diagram the one on the coolant elbow.
But then I went to the ETM section and its pointing me to X126, Connector C152 as the Coolant temp sensor which is the one I replaced:doh:

So the question is anyone know for sure which is which?

BTW the dash temp gauge is working fine.

Is the ecu sensor not located on the inlet manifold with a square type moulded plug similar to the injector plugs?

Yeah, thats the one I replaced.
The other one has 2 spades coming out of it, its just that the RAVE diagram under MFI section illustrates the spade one as being the sensor, not the moulded one as indicated in the ETM.

I am pretty sure you are right Spud. Pull the plug off the one on the elbow and see if the temp. gauge stops working. Maybe you have a dodgy wire/ connection on the lead for the ecu plug.

Sounds like you got the right sensor, have you run continuity tests on the wires?

If you can get the engine to at least run, try measuring the resistance of the thermistor and see if it changes. Resistance values against temperature are shown in Haynes book of lies.

Another thing you might be able to do is to swap the coolant temp. sensor with the fuel temp sensor ( I believe they are the same). If that doesn't sort it, I'm afraid you might need to think about looking at the ECU itself.

the sensor on the elbow is for the air con.

1992lse said:

the sensor on the elbow is for the air con.

Click to expand...

Thought that one was just a thermo switch for the fans?

More fun!

Neither sensor we've been discussing is the temp guage! I disconnected both and the guage worked merrily away, looked a bit closer and there is another sensor with a single wire beside the one with the black plastic top.

The sensor on the elbow with the two spades is the thermo switch for the aircon. I should've known as I've replaced it before

This means that the black plastic one must be the one feeding the ECU. Since I've replaced it there must be a fault somewhere else in the loom. Mind you I've not done the resistance checks.

As Kev says theres a fuel temp sender which is fitted to the fuel rail as well as the coolent temp sensor.according to my diagram the coolent temp sensor input is pin 17 at the ecu and the fuel temp input is pin 18.I wonder if the fuel temp sensor is at fault?