Guys, please help on this one.

My 2009 Fiesta judders when im idling. It doesn't happen all the time and it has no effect when driving. The revs drop down a bit and then go back up and you can feel the card judder when it does this. Ive taken it to ford and they have said there is nothing wrong with it, im not convinced!

I have kept up regular servicing on it and it is in very good health. If you open the bonnet and feel the engine you can physically see the engine jerk a bit. I was thinking it could be some dogy fuel or something.

Any Ideas on what it could be, and how to fix it?? Its not the aircon on or anything like that!

Diesel or Petrol? (Not that it makes a massive difference in this case), although cheap fuel may exacerbate the issue.

I don't profess to known loads about cars, but from my experience, some degree of shuddering at idle and "dipping" revs is normal due to the auto choke. Basically to save fuel the cars computer tries to get the revs as low as possible at idle without it stalling. Sometimes it can try to hard causing a slight judder before it pulls the revs back up.

Equipment in the car turning on and off can also make a difference, lights for example put more load on the electrics and thus the alternator, same goes for when the air-con engages.

If its doing it badly, there may be something wrong, but if I'm sat at idle, you can see the rev needle drop slightly every now and then and cause a slight judder. Its quite funny to watch an auto choke doing its job sometimes.

Its definitely not equipment turning on or off. As im pretty sure that this has only started since the last service. If its never happend before, why would it just start now.

Choke does sound reasonable I suppose but again wouldn't this have made it happen in the past too? When I took it to Ford, they put a new map on the computer thinking it could be that but that hasn't helped either. Oh, and its a petrol

Might be worth asking what was done at the last service. Seems odd that its only just started since then....

Was the service done by Ford too?

No, the last service was through another company. I will have a look at the servicing sheet and see what they done. Could it be a spark plug fitted incorrectly? Or filter fitted incorrectly?

Could be fuel or air filter.

These both got changed on the last service. Do you think one of them could be fitted incorrectly??

If fuel filters are not fitted properly then air gets in and will cause problems.

It's more of a problem on diesel cars but petrol cars are not immune.

I also noticed in my Haynes manual it said the fuel system in the fiesta is very difficult to bleed and gets air trapped easily when you change the filter

its not a choke issue, there is no such thing on a modern fuel injected engine.

it could be something like a dodgy spark plug, it does sound like you could have a small misfire. removing them for a look could reveal an answer, the should be a nice light brown/grey colour.

its not a choke issue, there is no such thing on a modern fuel injected engine.

it could be something like a dodgy spark plug, it does sound like you could have a small misfire. removing them for a look could reveal an answer, the should be a nice light brown/grey colour.

I know modern cars don't have an actual choke valve, I've just always called it that as the engine's computer does a similar thing by reducing the fuel to as low as possible without stalling at idle.

At the moment it does seem like it could be a number of things, I would take it back to the garage if it has been doing it since the last service. (Or Ford if you no longer trust the garage.)

Thanks so much for all your feedback.

I have taken it to Ford twice now and each time they said there is nothing wrong. Cars shouldn't be doing this. It didnt do it when I brought it brand new in 2009 and there is no reason for it now. I will take a look at the fuel filter and spark plugs when I get a chance and keep you guys updated.

If there are any more ideas, give me a shout.

Cheers