Member Since: 02 Mar 2015
Location: Melbourne
Posts: 38
I've been told not to remove the butterfly as it provides torque dampening right just before changing gears to reduce stress on the gearbox, what's your thoughts on that?
Everywhere else I have read the general consensus is to remove the butterfly?
Cheers2007 Disco 3 2.7 TDV6
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Reddahaydn
Basically your vehicle would never see a case of both the Butterfly flap and EGR Valves being closed at the same time.
Simplistically.
Wide open throttle, EGR valves closes and Butterfly fully open.
Partial throttle / light load driving butterfly flap only open a tad and EGR valves open.
If you leave the butterfly flap in place then you could put the engine in a situation it was never designed for, EGR closed (due to being blanked) and butterfly closed (as on overrun) this would create a vacuum/depression within the engine, that could cause damage to engine seals etc.
I guess in the worse case even result in oil pullover.
There you go. clear as mud
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2nd Jul 2015 7:02 am
Reddahaydn
Member Since: 02 Mar 2015
Location: Melbourne
Posts: 38
Thanks mate - Interesting. makes sense to a point - However - does the butterfly flap on the intake every fully close?
If it did close fully and EGRs were fully open (when not blanked off), all you would be getting is exhaust gas which has all oxygen in it, so you wouldn't get much fuel burning. My 'limited' understanding of EGRs is that they only recirculate a little of the exhaust gas to mix with the oxygen from the intake - to lower the combustion chamber temperature which is how they reduce pollution.
Happy to stand corrected if I am wrong. Cheers2007 Disco 3 2.7 TDV6
LLAMS / 265/65/18 BFG ATs / Safari Snorkel / Spare wheel carrier / 100L Long range tank / Traxide SC40 dual battery isolator / Optima Yellow Top / Autologic Remap / Front Runner Slimline II Roof Rack / Cross drilled and slotted rotors and ceramic pads / Front Runner drawers / UHF / Rasta front skid plate / Waeco CF50 / Mitch Hitch / Tint / Parrot MKi9200 Bluetooth Phone & Audio
Going down hill, foot off the throttle, then the butterfly will be closed, however the EGR's will not be closed.
SydIn Spain - 2018 F Pace - Down and out's Velar
In UK - Dare not say on this Forum
Gone - Lots of Lode Lane vehicles.
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3rd Jul 2015 6:51 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Im not so sure about that as when going down hill with foot off the throttle I would guess injectors are not injecting so no combustion is taking place so egr not actually doing nowt?
3rd Jul 2015 7:05 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
With negative torque the engine does go into Diesel Fuel Shut Off (DFSO) mode so the injectors stop squirting in the diesel. Pulse width limits on the injectors is one of the major reasons for this mode as once the pulses get so short they lose their linear response and rich/lean management becomes an issue. There are exceptions to the DFSO strategy to help control cat and DPF temps, but only at the extremes.
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Sorry for asking, but we are talking here about the butterfly valve on the intake path on a diesel engine?
If so, from what I know, the butterfly valve will fully close on engine shutdown in order to reduce engine shudder and partially close when regenerating the DPF in order to help raising the EGT.
Otherwise the butterfly valve will be fully open all the time.
On a gasoline engine this will be a complete different story.
3rd Jul 2015 4:29 pm
geoff.
Member Since: 24 Jan 2010
Location: West kent
Posts: 8531
so what are you saying alex , is it a good thing or bad thing to remove the butter fly
3rd Jul 2015 7:48 pm
alex_pescaru
Member Since: 19 Dec 2010
Location: RO
Posts: 270
I, for one, I will never remove it because that valve has another role.
In the unfortunate event of oil entering the inlet manifold (turbo bearings failure, for example), the engine RPM will rise uncontrolable. The ECU will see this and fully close the butterfly flap in order to stop the engine. So you will not ruin your engine as in the case when you removed the valve.
4th Jul 2015 6:31 am
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20855
But the butterfly is not a perfect seal, and air will still pass the flap, and will do nothing to prevent an engine runaway
FWIW, I have not noticed a difference in engine shut down between those with, and those without the butterfly flap...My D3 Build Thread
If so, from what I know, the butterfly valve will fully close on engine shutdown in order to reduce engine shudder and partially close when regenerating the DPF in order to help raising the EGT.
Alex, only the models without DPFs (all UK spec D3s) can be blanked anyway. Current: Discovery 3 06MY (55 reg) HSE Auto Zambezi Silver Allisport Fast Road Intercooler, V8 Brakes, Silicone IC Hoses, EGRs Blanked, Remapped, De-Cat pipe, FBHIC
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4th Jul 2015 7:42 am
Reddahaydn
Member Since: 02 Mar 2015
Location: Melbourne
Posts: 38
So if the butterfly doesnt seal enough to stop an engine runaway, it also wont seal enough to create a vaccum in the engine that can do any kind of damage.
From someone who has played with holding rags over a snorkel head, the engine starts dying well before the inlet is fully covered. Imo the butterfly closing would be plenty to stop a engine runaway.
As to whether doing that creates a vaccum i dont know.2007 Disco 3 2.7 TDV6
LLAMS / 265/65/18 BFG ATs / Safari Snorkel / Spare wheel carrier / 100L Long range tank / Traxide SC40 dual battery isolator / Optima Yellow Top / Autologic Remap / Front Runner Slimline II Roof Rack / Cross drilled and slotted rotors and ceramic pads / Front Runner drawers / UHF / Rasta front skid plate / Waeco CF50 / Mitch Hitch / Tint / Parrot MKi9200 Bluetooth Phone & Audio
5th Jul 2015 10:22 pm
lukeangus
Member Since: 22 Aug 2016
Location: san jose costa rica
Posts: 5
Holy thread resurrection Range Rover Westminster 4.4 TDV8 what a car
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25th Jan 2019 6:16 pm
lukeangus
Member Since: 22 Aug 2016
Location: san jose costa rica
Posts: 5
Indeed, I am not very techy when it comes to cars, but getting royally where I live on parts and as I am not very techy, I have no idea if this is worth doing or how to do it! Parts here are double what they are in the UK!
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all oxygen in it, so you wouldn't get much fuel burning. My 'limited' understanding of EGRs is that they only recirculate a little of the exhaust gas to mix with the oxygen from the intake - to lower the combustion chamber temperature which is how they reduce pollution.
Allisport Fast Road Intercooler, V8 Brakes, Silicone IC Hoses, EGRs Blanked, Remapped, De-Cat pipe, FBHIC
)
