Hey Steve.
The fiesta diesel has long had problems of this nature .. in the later year 03/04 models it got worse .. and even fords have still, to this date not rectified the fault on those models .. on models post 2006 A new ECU was fitted with updated settings and this seams to have rectified the fault .. but there has been numerous attempts by fords to rectify this issue on earlier models ...along the way changieing parts here, there and everywhere ? ... I'm going to advise you to change the the EGR valve, this seems to rectify the fault sometimes from the outset on earlier models ..but it may return ... also remove and clean the MAF sensor ..
Hope this helps .. keep me posted !!
Monday, March 23rd, 2009 AT 9:45 AM