After various local "experts" failing to diagnose the cause of my daughter's Mondeo "misfiring" i.e. running rough / hesitating / surging at low throttle openings, I posted here a little while ago on the subject. One of the suggestions as to possible cause (for which, thank you) was an air leak, but I couldn't really find anything, so I decided to take the empirical approach by disconnecting things one at a time to see if the symptoms changed. Trying to be slightly logical (!) and still thinking about air leaks I moved my attention to any 'vacuum / air' pipes that looked like they might be possibilities. To make a long story short (oops, too late!) disconnecting the pipe between the exhaust gas recirculation valve and the EGR valve solenoid produced a dramatic improvement in smoothness of running. I verified that it wasn't my imagination be re-connecting the pipe and sure enough, the problem returned. Sealing the openings on the EGR valve and on the vacuum pipe with gaffa tape to prevent ingress of contamination (just 'cos it seemed like the right thing to do!) also brought the problem back again. Of course, I should've sealed 'em one at a time (isn't hindsight a wonderful thing) but anyway, to "cure" the problem, the vacuum pipe leading to the EGR valve solenoid mounted on the bulkhead must be left open to the atmosphere. I have yet to see what happens on a cold engine, but certainly with everything at normal operating temperature, I seem to have found the magic "cure" - which, of course is just a workaround really!
So, the question - ok, two then:
1) will there be any long term adverse effects of not having this pipe connected? 2) will it effect the emission readings on the next MOT and therefore need to be re-connected before the inspection.Thanks, people.