I have a 2006 Mondeo TDCI Ghia (full service history, 47k miles) and have read all of the conversations regarding black smoke and issues with the EGR Valve. Having cleaned the valve and having had the car in with a Ford dealer for a week now, I am pulling my hair out - Ford says it can find no faults with the car. They remapped the ECU and while the (always black) smoke is significantly less than before, it is nevertheless present, particularly on the motorway, with small depressions of the accelerator in 4th and 5th gear.

I cleaned out the existing EGR valve in accordance with all of the blogs (but not the mainfold itself) and have had the fuel filter replaced. I only use Shell V Power fuel, and I have tried the 'italian tune-up' alluded to in a number of conversations.

Recently, I decided to see what happened if I simply unplugged the EGR's electronic connection - and while there is an initial puff of smoke in the initial accelartion thereafter, it basically disappears in its entirety after that - no smoke whatsoever irrespective of how I drive.

Performance has never been an issue - it has remained smooth throughout this episode - and no warning lights on the dash have ever appeared. No wooshing noise and no loss of power or poor fuel economy - reckon I'm getting about 50mpg iaw computer...

So - what do I do now? I want to avoid the engine warning light coming on and am therefore reluctant to leave the egr unplugged permanently. I am also nervous about fitting one of the blanking plates - I appreciate many have written that there is no risk and that the EGR is for EU legal purposes only, but I cannot help but think there might be some second order unintended consequences.

I have ordered a brand new EGR (genuine ford part) off of ebay for just £80 - but will replacingit simply make matters worse. My theory is that the EGR is sticking open - after reconnecting the electronics, there is only limited black smoke for about an hour, but then it comes back.

So my questions are as follows, and would be extremely grateful for any advice.

1. Shall I replace the EGR valve with the one I have just bought, or will thatmake it worse?

2. If after disconnecting the EGR electronically, an engine warning light comes on (blogs suggest this will happen after a few days), will it simply go out again when I reconnect - or do I need to get a ford dealer to reset it.

3. Does fitting a blank also bring about an engine warning light.

4. Does fitting a blank lead to other second order consequences - premature wear of the engine, etc.

The car has only done 47k prior to me buying it 5 weeks ago - and I guess the previous owner only did little trips about town, but when I cleaned the valve out, it didn't seem that bad at all - but I do not have the mitac pump to check whether it is opening and shutting as required. I have tried doing the italian tune-up throughout a subseuqnet 2000 miles, but things are not getting any better.

Thanks

Matt S