My 02 plate 1.6 zetec (se) focus estate automatic has developed a very rough idle prob as soon as I release the throttle it drops revs and stalls sometimes it will keep going but very roughly .

As you can imagine with it being an automatic trying to go around a roundabout with the engine stalled trying to put it in nuetral wrestling with steering and starting the car is a nightmare.

I also keep getting the eml coming on with no code checked with my own reader and a local mobile mechanics one.

I have changed so far MAF and O2 sensors ,coil pack and leads/plugs (regapping plugs to 1 as they where 1.3) also done a full filter change air/fuel and oil with change of oil all with no change.

My sister in-law as the same engine as me so I borrowed her iacv as her engine is running fine but the problem still persists so I know its not the iacv.

While having another look today I wiped off all hoses I could get to to double check them and found a split in one with tape around it the idle was 95% better so I think I have found my problem .

All I need now is to find out what the hose is called or its part number I am posting a pic below.

it is situated below the intake manifold near the iacv if anyone could help me with identifying this hose I would be most grateful.

Does it have an Exhaust Gas pressure differnetial valve? the old mondeo Zetecs used to show exactky the same symptoms when that went

If the EML is on there is definately a fault code, get a better reader

I had eml checked by a local mobile mechanic using his reader and that showed no fault aswell.

With the split pipe temp patched with tape (not very well it's hard to get tape around it without dropping the intake manifold) the idling is around 95% better so I am more or less certain it is this pipe thats the problem I just need to know its name or part number.

If you look at the pic you can just about see the split.

After a concise googling it is the pipe that is part of the pcv valve assembly the pcv is located under intake manifold and the pipe with a split is the right hand part so it's off to ford in the morning.

Thanks for looking people.

A Vacuum leak will cause rough idling, and misfiring at crusing speed,

If its holey replace it,

New saying goes, an engine warning light does not have to be on for there to be a fault.

Faults do not always register as a Fault Code

From experiance not heresay

Jamie

That's the pcv valve pipe work in there