i have a an iveco van 2.8 turbo y978kne engine starts runs fine but when lifting off accelerator a red lite comes on dash and i have to dip the clutch to reduce revs or put in neutral to put engine under load to get power back this only happens on overunn otherwise fine?
Usual cause of this is the high pressure pump. As the pump wears out it actually over-fuels. If the van is fine when under load (accelerating up a long hill for example), but only causes a problem when you back off, then that's the HP pump on it's way out. So far I've not found a specialist who can repair these pumps cheaper than the cost of a new pump (about £350 from the dealers).
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lorries/trucks.