Emissions Fail

[bobthecabbage]

Originally Posted by dingov70

The only accurate way to determine coolant temp is by fitting a thermocouple into a coolant line & reading the display on the meter . I have a cheap digital multimeter with this facility , about £30 . You do loose a little coolant BUT remember your cars display is only an approximate reading of temp , fuel level or speed not certified acurate .

You can also use a snap on type scanner to perform live data reads BUT again , these rely on the sender being accurate in their output

Granted on the accuracy of measuring the coolant temp.

On the engine management side though, the ECU only needs to see the correct temp signal in order decide that the engine has reached operating temp. Otherwise it's going to run in warm up mode permanently, reducing fuel efficiency and harming the cat etc.

So your thermostat needs to open at the correct temp and you coolant temp sensor needs to read the correct temp in order for the ECU to achieve normal operating mode.

I think the thermostat in my diesel is opening a bit early as my fuel economy is poor and on hot days its much better. However there are countless other things it could be!

[Haizum74]

Originally Posted by bobthecabbage

Granted on the accuracy of measuring the coolant temp.

On the engine management side though, the ECU only needs to see the correct temp signal in order decide that the engine has reached operating temp. Otherwise it's going to run in warm up mode permanently, reducing fuel efficiency and harming the cat etc.

So your thermostat needs to open at the correct temp and you coolant temp sensor needs to read the correct temp in order for the ECU to achieve normal operating mode.

I think the thermostat in my diesel is opening a bit early as my fuel economy is poor and on hot days its much better. However there are countless other things it could be!

Originally Posted by bobthecabbage

In the manual there is an indication of the correct thermostat temp. At least in the phase 2 manual anyway.

Can't remember what page but towards the back. Maybe in specifications or something like that.

From memory i think its 90c. Even taking into account a + or - of being out by 3c it is still showing below recommended temp range and as it's a cheaper option it isn't going to hurt changing it even if that doesn't correct the issue.