New car not running quite right at the minute...

[whiskychaser]

Glad to hear you got it sorted! The big bonus is it didnt cost anything. Now all you have to think about is what would you do if it wasnt as simple as that Big of you to come clean about it Result

[e34.535i.sport]

Haha thanks Colin - I'm too honest to be a proper scouser I think

Looks like I spoke too soon however because I got 9.9mpg on the way to work this morning! If I was hammering it I wouldn't mind but i was driving 'normally' ... Seems to have gone back to using silly amounts of fuel almost overnight, which seems strange. I'm only basing this off the OBC but I know it's relatively accurate by how many miles I'm getting for 1/2 or 1/4 tank etc I have been getting. I wonder if the o2 sensor is working inconsistently rather than not at all? I've been searching around and found that coolant temp sensors can also cause fuelling issues?! I can get one of these for less than £10 so I might just do that, but not quite as easy with the o2 sensoras I'm looking at around £80 for that If I didn't think I was in danger of killing the cat by running rich I wouldn't be so worried but as they cost a small fortune I need to see if I can trace the source the problem!

[whiskychaser]

I thought you might have 'borrowed' one of the big 'scopes from a lab at work and checked the O2 sensor(s). Just imagine you driving around with one on the passenger seat and a belt round it. Imagine you explaining it to the bizzies (they still call them that?) - 'Yeah its my sat nav' Its hard to say if the temp sensor is duff or not without reference to spec. Clearly if its not working then the ECU thinks the engine is still cold and you are effectively running on 'choke'. If thats the case the exhaust will probably stink of fuel and it will run lumpy. Maybe check the resistance of the sensor when cold, at 1/4, 1/2, 3/4 and hot on the gauge? You should see some logical change but it may not be linear.

[BMW4LIFE]

my bets still on the O2

Think of it this way...if you plan on keeping the car for a while that O2 will need to be replaced so whats another 10000 miles....

IDK if I were you I would bite the bullet and go for the O2

then if the problem remains unresolved then I would sell it and buy a Honda Accord!

jk

I hope it works out for you bud!

[e34.535i.sport]

Haha ye the 'bizzies' (we also call them other things that I won't go into! haha) would not be impressed with that!

So do I check the resistance with a multimeter then yes?! I'm useless with electric stuff give me suspension anyday my primitive mind can just about handle nuts n bolts!

Cheers JK i'm tempted to just change both sensors and hopefully be done with it... If I don't procrastinate for too much long the decreased fuel consumption will offset the price of the sensors anyway I suppose! (Normally I'd just do it but got a mortgage on the horizon now and Christmas is looming!). Better get over to ebay I think...

[whiskychaser]

Yeah a multimeter is fine. You are only checking the change in resistance:
http://www.jaguarfuelinjectorservice...e%20Sensor.htm
Dont know if this is bang on for the XJR but gives you a clue

[Grantus]

If there is a coolant sensor that reads temperature and is faulty, that can cause excessive fuel consumption because it tells the computer that the engine has not reached operating temperature and the mixture then becomes enriched.

[e34.535i.sport]

I 'bited' the bullet and bought both sensors. The o2 sensor is a PITA to get at (well at the connector end anyway!) but will be able to change them over myself which is a plus. Ended up searching around and getting both for <£80 from 'Britishparts' which I was quite pleased with

If that doesn't help it will give me an excuse to come over and visit anyway ay Colin?!

[whiskychaser]

There isnt anything in the 'service bay' at the moment John

[e34.535i.sport]

There isnt anything in the 'service bay' at the moment John

Ha ha ha I like!