Posted 21 December 2012 - 06:24 PM
I think everyone has covered this well - here is my tuppence worth
There is a lot of misinformation on the net about this, often you hear "why did Ford/ etc fit EGR valves/ systems in the 1st place" / you need them for the MOT (not on diesels) etc - i think it is ignorance/ fear of the unknown that prevents people from fitting the plates, overall you are better with a blanked/ disabled EGR valve system than a working one, on a diesel.
Taking the dirty waste gasses from the exhaust and feeding it back into the inlet (even in small amounts) is never a good thing - and un-nessesary on a diesel engine IMO, and i think most engineers/ tuners would agree.
Yes, its a good thing to blank the EGR valve, a solid blanking plate can "fix" a faulty EGR valve
A replacement EGR valve can cost 100s, it may have to be replaced several times (4 times, in one case) during the liftime of the vehicle - a blanking plate costs about a fiver
A Euro 3 should be able to be planked with no problem, a Euro 4 may put the engine fault light on (EML) (sometimes after quite a long time/ or soon after the EGR is blanked) but normally does not cause any other problems, the light staying on can be annoying (to some) but this can be ignored or can be reset with a suitable code reader (some drivers do this once a week)
EGR blanking plates have been made with holes in them,(to let the gasses through) in an attempt to stop the EML coming on, these cannot be used if you have a faulty EGR (solid ones can) and defeat the purpose of the blanking plate
So solid (no holes) blanking plates are essential, stainless steel (mild steel can rust, aluminium can melt - its exhaust gasses) and a decent thickness is preffered (3+mm or thicker, )
Once the blanking plate is fitted, apart from "fixing" faulty EGR valves/ systems and preventing problems in the future, it prevents carbon build up in the inlet manifold (best to clean this out) and potentially improves the reliability of other components (eg - the turbo inc. turbine/ variable vane mech/ actuator - by reducing smoke output/ carbon build up )
Fitting a blanking plate can reduce flat spots, turbo lag, and improve throttle recponse, performance and economy (a little bit) - as engines run better on clean, fresh cool air rather than burnt, warm carbon.
Fitting an EGR blanking plate will not cause a UK MOT fail, and often helps (by reducing smoke- only particulates are measured - 2012/2013)
So its a bit of a win- win situation pro solid stainless steel EGR blanking plates