We have recently purchased a 56 plate focus tdci. The dealer has just been fobbing us off so have taken the car to an independent garage for them to try to figure out what is happening... The car itself starts and drives perfect until you reach 181 miles of driving (during the week) then it will jump and keep jumping until you lock the car and sit it out for 5 minutes (sometimes this won't work and it will be like it the rest the day but then fine the following day) now once in this mode it will lose power-but won't stall - will suddenly regain power. We have so far changed the fuel filter. It's been hooked to diagnostics while driving and was reading temperature of -56 ' c. ... any recommendations??

 

Assuming this isn't a dealer's problem (which it usually would be if you bought it from the trade)...

When you say '-56C' what do you mean; Oil temp water temp or air temp? In any case that's probably a sign that a sensor is not being read. The sensor itself has failed the wiring has failed or the module reading it has failed.

The wiring including connectors is probably the easiest so start there.

Also I'd guess that you might get a reset by disconnect the battery for a while but ensure that you have any radio code first.
 

I'm afraid to say we did buy from trade but as we can now see a very dodgy one... They claim nothing is wrong when it clearly is they fitted a new fuel filter then don't know what else to do or try hence now taking it to a mechanic we know who thought could have been the maf filter but after disconnecting it still done it. Air temperature is the minus figure. 

Thank you for your reply ill give it a try! 

 

All checked an all wiring fine, still doing it every 181 miles driven... any thing else to try?

I would replace the sensor it self, after that do an oil change for peace of mind likely the dealer didn't bother with that either. 

See how it goes from there, if it's still being a bit dodgy go to a different garage don't tell them anything about you've only just bought it explain what's wrong and they might be able to help you. 

Thank you for your advise. Will give it a go with the oil change and new sensor. We've gone to another garage and they are the ones who found out the temperature problem. They've had it in diagnostics whilst the car is in its jumping mode and loss of power and nothing is coming up and all pressures are normal - it's got us all a bit stumped. 

Oil changed and sensor and still the same!! We've phoned ford and they don't have any idea why it's doing it either! 

so the air temp sensor is still showing -56? and when you say air temp do you mean intake air temp?

and what engine, 1.6,1.8 or 2.0?

2.0. I'm not sure he said it was reading that temperature which it shouldn't be....

It's a new sensor on now so haven't had  retake on temperature.

did you change the sensor or a garage ? 

after replacing sensor it should have been checked that it was reading correctly. thats what needs doing first before doing anything else.

 

 

Garage done it, nothing was said just that it wasn't the problem 

thats not very usefull then, i would have thought they had said temp now reading ok and still you have problem, or still reading -56 and you still have a problem

and i hope they changed the right sensor, 2 sensors very close to each other, one is iat sensor , and other is map sensor. or have they changed the maf sensor next to air filter?

Maf sensor was changed. Spent a lot of money trying to fix it that's why came on here as got a baby on the way in august so need it sorted and no one seems to know what todo at either garages... It started to jump as I was gojng to stall but now it jumps few times then looses power (foot on accelerator nothing happens) then will kick in but still jumps. Sometimes if you take keys out and lock the car it will stop until next 180 miles driven but sometimes it will keep doing it for the rest of the day but then following  day will drive fine

*as if It was going to stall*

Have you tried plugging in a ELM cable and checking for codes?

Yes absolutely no codes show up at all not even when in the jumping mode

so the mass air flow sensor was changed due to -56 intake air temp? that could why it hasnt fixed it, perhaps the intake air temp sensor should have been changed instead.

as ryan said , think you need a  bluetooth or usb adapter and torque pro or forscan etc to diagnose yourself.

 

 

Think I will and also have a look at the intake air sensor too. too . Thanks for all your help and quick responses 

what code reader do you have? if you can read live data, bring up the iat sensor and see what temp it is

I haven't got any readers but rely on my mate who has his own garage and all the readers who has been helping me