There was a whole thread discussing the role of the butterfly valve, and I think the conclusion was that it worked with the EGRs to reduce the pressure (or increase the vacuum, whatever) in the throttle valve assembly so it caused the exhaust gases to drawn in to the throttle valve via the EGR valves. So with the EGRs blanked (but butterfly still in place) the engine is starved of the flow of air it needs. With both EGR valves and the butterfly valve in place the engine, under certain conditions, would 'consume' a mix of 'air' and inert exhaust gas, whereas with the EGRs blanked and the butterfly removed it just gets pure 'air'. Don't get the butterfly valve confused with the throttle valve - the butterfly would only (partly) close when the EGRs are allowing gas through, which think is when the engine is steady 'cruising'. The EGRs aren't open during acceleration or deceleration as far as I'm aware.
In answer to the original Q, remapped and blanked (with butterfly removed) - the best 2 things I ever did to this engine I can now maintain 90 mph all the way up Haldon Hill on the A38 near Exeter in 6th (manual) carrying 4 adults - the only other car I could do that in was my Boxster S (with just 2 adults of course!)Previously:
2005 D3 2.7 TDV6 S
1984 90 2.25 Petrol CSW
1992 90 200TDi Hard Top
1995 Discovery ES 300TDi
2003 90 TD5 Truck Cab
13th Nov 2008 11:49 pm
Valleyforge
Member Since: 16 Nov 2006
Location: Westmorland actually
Posts: 188
Mine's just failed & is being replaced under warranty (2 year old, 40,000 miles). What would it cost if out of warranty ? I liked my D2, but my D3's better ....(& the RRS better still)
19th Nov 2008 12:31 pm
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
zaphod wrote:
simonsi wrote:
..... rip out the strangulation butterfly valve too - massively reduces the "roundabout hesitation" that the TDV6 is prone to ........
I thought the butterfly was used for the engine braking? Could be mistaken tho.........
Engine braking comes from "pumping losses" ie with no or little combustion you get more engine braking by the engine compressing air and the effort that entails. Closed throttle on a petrol starves the engine of air so little engine braking (other than engine friction), closed throttle on a diesel means (normally) loads of air but no fuel so little/no combustion. This is why diesels provide loads more engine braking than a petrol engine. The butterfly valve starves the TDV6 of air when it is closed, minimising and engine braking (if the EGRs are blanked) and causing the lack of airflow which causes the turbo to spin down, re-applying the throttle then means a delay while the turbo spins back up....Cheers
Simon
19th Nov 2008 4:32 pm
GLYNNE
Member Since: 06 Oct 2006
Location: KENT
Posts: 4656
Mine is chipped and mine has failed
Quote:
Mine just failed & is being replaced under warranty (2 year old, 40,000 miles). What would it cost if out of warranty ?
My dealer managed to try and get £2500 of me Saying that the butterfly mechanism needs replacing,and that the turbo had blown. Well to cut a long story short i got it back of them and blanked the egrs and removed the butterfly all for £25 plus a site donation
19th Nov 2008 9:45 pm
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
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I can now maintain 90 mph all the way up Haldon Hill on the A38 near Exeter in 6th (manual) carrying 4 adults - the only other car I could do that in was my Boxster S (with just 2 adults of course!)
Mine is chipped and mine has failed 
