How would I check if the thermostat is stuck open ?.

 

Temperature. If the car does not come up to normal operating temperature ( gauge needle at 12 o clock) then it is likely stuck open. The other way is to feel the top radiator hose as the car is warming up. It should stay cold until the thermostat opens and then will become too hot to hold. It might get slightly warm, as there is a bleed and some minor circulator through the radiator, but it shouldn't be as warm as the housing on the engine.

If you have a laser thermometer, just measure the temperatures on either side of the thermostat as the car is warming up. There should be a difference. If there isn't, the the thermostat is open.

 

Remove it and put it in a pan of water if it isn't open. Heat the water and note the temp. when it begins to open and when fully open.

Or just replace since it's not expensive.

 

I'd just replace. What do they cost? Maybe a tenner? If that?

And they aren't hard to replace... Thermostats should be replaced regularly anyway...

 

I have changed MAF sensor today. I'm yet to check the car to see if its any better than before. If the problem is not resolved. Any suggestions on what to try next ?. Also I have uploaded a image of my car engine bay can anyone please explain what 1 and 2 sensors are for ?.

 

The car does not seem to smell of petrol anymore. I just need to take it for a drive to see if its better on fuel. I also noticed one difference but not sure if its relevant. But the average mpg on the trip computer is taking longer to work it out. Before it was instant.

 

Great. Glad to hear a new maf improved it. I remember cleaning my old maf did not give any improvements. Changing it was like night and day though. .

 

i noticed that mine x300 xj6 on idle it drinks like 1 litre pretty quick... and i have smell from exhaust with a lot of smoke when cold weather even if the car is on for 30minutes or more... when i start rolling all the smike disappears... thermostat? Should i check catalytic concerters? I recently replaced half way from the rear the exhaust since it was broken completely... 264.000 km

 

 

I did change the Thermostat. The temperature runs in the middle now. I am still getting on average 12.1 mpg. I have filled it up with fuel to check it is accurate and only just get over 200 miles to a full tank of gas. On my handheld OBD II it says the following error code in the attached picture. It is only a cheap tool to be honest though. It seems strange have had two Jaguar XJ6 4.0 cars same age and same problem both cars. The first car I never sorted the problem out and sold it in the end. Any recommendations on a fair price good tool with data stream on it as well would be appreciated ?.

 

ELM327 , about $ 12 US on Ebay before Trump tariff . There is a learning curve but will look at all ECU data and record a log as you drive around . Look for the unit that includes software and you may opt for better software later . Have you looked at the 2 wire engine coolant temp sensor and inlet air temp sensor that effects fuel trim ? See page 78 and 86 as you dip it in ice water to verify in the file below:

http://www.jagrepair.com/images/Trai...20-%202000.pdf

 

I have changed both the engine coolant temp sensor and inlet air temp sensor for used sensors. I do not have a pc laptop so I am looking for a OBD II handheld device that has a Android App so can use wireless ?. Any ideas on where I can get a good android app that will support data streaming as my current tool does not ?.

 

here we go again - code P1179 came up again and looks like i need t replace another 02 sensor How do i know which one this time>? replaced right downstream over a week ago - was fine - today - light back on - code back. help 1996 XJR SC 6cyl..

 

On 1996 XJR 6 cyl sc shop print out says : Long Term Fuel Trim Too Rich-Banks 1 and 2 ( AMFR) i thnk for BMW?

 

what does error code P1179 mean in a 1996 XJR SC ??

 

1. Check MAF
2. Check exhaust for leaks
3. Check fuel pressure

There is a TSB 18-53 on this code.