I have a BJ 2 litre turbo diesel. Through most of the year the engine pulls like a train without missing a beat, however as soon as the outside air tempurature drops below 10 degrees the engine seems to have no power and struggles to pull until the engine gets to a very warm tempurature. It always starts first time and never misses a beat. I am guessing there must be a faulty temperature sensor somewhere, any thoughts anyone?

I don't know engines that well and haven't got a clue what the diesel engine is like, but maybe the temperature gauge near the MAF?

*Waits for a real expert*

hmmm stick a hairdryer in front of the air intake on a morning like that and see if it makes a difference. It might be too cold in the engine to get the diesel to burn decently. No spark plugs remember - just glows. Not sure how a diesel engine compensates for the cold air in winter though....

*Also waits for a real expert*

A mate had a diesel for a while, used to just turn the electrics in the car on for a few minutes to let everything sort itself out before driving.

The glow plug's heat up the combustion chamber to get the car going, After that the diesel engine will keep running by it's self,

I would say you probably have a faulty temp sensor of some kind ( well done matty ),

Best bet is to get it onto a diagnostic reader and that will tell you all you need to know.

Stu

could it not also be faulty glow plugs then?

Yep could be, if its not heating up the cambers to cuase proper combustion then it wont run right, I would have also though it would have been evident by a load of black smoke when you rev it (More than normal anyway)

Nope because it won't start with faulty glow plugs.

if they are on their way out it will take longer than usual to start the engine.

Yep, I'd agree with Stuz there - if it's still starting on the button the glow plugs are probably fine - it does sound like a temp sensor somewhere

Thank's for all your thoughts. No problem starting so don't think the glow glugs are a problem, but lots of soot when reved to the limit. I had the EGR valve off tonight and cleaned and tested it, just in case, but that works fine too. Keep the ideas coming please.

Not unusual for a Diesel mate, they all do it unfortunately.

Like I said a Diagnostic check would be the best thing for the car, Sensor's are not easy to find otherwise.

Stu

Glow plugs will help the engine start, but some will stay on until running temp is reached, dunno if the BJ does this or not.......

Diesel fuel can freeze, so its likely to be affected by any temperature drop much more so than petrol. The vans at my work run like bags of shit on cold mornings, and they're all brand new!

Just to update you all. Took the car to the local Mazda dealer, mechanic there said the turbo was worn out as it wasn't boosting. I wasn't sure that was right as these IHI turbo's go for ever, so took it to a local diesel expert. He confirmed there was nothing wrong with the turbo and, after doing some vacuum tests, discovered there was several vacuum leaks causing one of the vacuum solenoids to fault. So after replacing a couple of pieces of pipe, the BJ is now back to it's old self. It actually feels like a new car again! ........ all I have to do now is go back to my local Mazda dealer and try to get my money back for the miss diagnosis.

good to hear it's all sorted mate

can you tell me what pipes are the vacum ones and which ones to replace as i have the exact same problem cheers

I replaced some of the small pipes, about 10mm dia, that go down to the vacuum solenoids that are under the air filter. Also check the small lengths that go to the sensors and vacuum pump on the top right of the engine. The large diameter pipe going to the brake servo was also showing signs of cracking. My motor has done 220,000 miles, so the perished pipes were quite obvious, yours may not be so obvious. You may need to take them off one at a time and give them a thorough visual check. Good luck

Cheers much appreciated i will take them all off and have a look i'll post the outcome . I wonder if this is a common fault as mine has done 140 thou