This is a bit long, but highlights everything I think I've I've learnt in the last 14 months before deciding what I'm going to do.
If the EGRs are mechanically blanked off while working OK, I don't think any of the 3.6TDV8s will generate fault codes just for being blanked off (my 2007MY car certainly doesn't & I've not heard of any MY that does, yet).
On the 3.6 TDV8s and probably the 4.4s, there is an electrical cross-check in the engine ECU software that checks actual movement of the valve head vs movement demanded, it might also check the current required. THe EGRs are fed a signal by the engine ECU to actuate them 10 times when either the engine starts or stops (I can't remember which). If the valve doesn't move as designed or the current is incorrect - eg due to partially sticking or fully stuck valve - the engine identifies a fault & lights up the Engine Management Light (EML).
This 10 times operation may also help to remove some carbon build up on the valve stem.
If the EGR is blanked off the cross-check still happens if its not been mapped out by a software tuner.
While the EGRs remain OK, no problems are reported & no fault lights will operate.
However, because the valve is still operating, it can still still fail electrically or mechanically - it's just highly unlikely to fail due to carbon build -up.
On my 3.6TDV8, on of the valves failed nearly a year after being blanked off - causing the EML to illuminate.
If you've got a diagnostic tester, you can identify the cause of the warning light & choose to ignore it as you know it's not an actual problem. However, at MOT time, it will cause an MOT failure, so does need dealing with.
To eliminate the EML warning you've now got 2 choices :
1 -changing the EGR for eg a known good s/h unit (its not important what the quality of the replacement is as its not doing anything functional for the engine - it just needs to "pass" the electrical test in the ECU OR
2 - getting a software tuner to delete it out of the engine ECU so it can't generate a fault code / EML illumination.
BTW I've seen nothing yet that clarifies what the software tuners actually do. They could "just" remove the output to the EML or they could prevent the EGRs from actuating & prevent any related fault codes.
If all they are doing is preventing the warning light operation, BEWARE, because if you don't mechanically blank the EGR off, it could still be operating & could still fail mechanically.
By now, most people should know that the worst case EGR failure is the valve head breaking up & being sucked into the engine & then going through the turbo(s), causing catastrophic engine damage (Incidents reported in this forum)
Removing the EGR fault codes via the engine software seems quite expensive with some of the reputable "mappers" - maybe because they are doing it safely & comprehensively & to me replacing the EGR ro remove the fault sems a much cheaper option, together with mechanical blanking.
I worry what the "cheap" mappers are doing to "delete the EGRs" - are they just removing the warning light operation OR are they doing it properly to stop the EGR operating ? If the former, don't waste your money - you could still have a future engine failure !!
THe only way to know what the tuner is actually doing is to couple up a "loose" egr to the relevant connector on the engine wiring loom & watch what happens when the engine is started & stopped (I've done this on mine, which is why I know about the 10 times operation check). If the EGR still moves, you've got a dangerous set-up that definitely needs the EGR blanking off !
PS If I've got any of this wrong, I'll happily update this, but it's all of the info I've gotten from various forums so far Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk
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