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blocking EGR valve/pipe on TD5's
Moderator: Micka
This is a new religion here in the UK! Not defending any of the commercial parties involved. But amazed how many people over here seem to need a meaning in their lives.tony cordell wrote:Scrapiron are to be avoided at all costs
the copy other products and rip them off as their own
Wonder if they all wear T-shirts and make stickers to defend their local butcher against the big supermarkets?
They need to get out more.
Tim
Life's too short for a full time job
Hi Popeye, close but no cigar...popeye wrote:I always thought EGR was a good thing. But only know about its use on petrol not oil burners. With petrol the exhaust gas contains a certain amount of nitrus oxide.....
The idea of recirculating exhaust is to cut down the nitrides formed at
high combustion temperatures. The EGR should ONLY open and let
the exhaust into the inlet manifold when the engine is hot and the revs
are mid range or higher. When the engine ingests this lower oxygen
charge the exhaust gas temperature falls to a level where nitrides are
not formed.
If the EGR is stuck open when the engine is cold or at low revs
then low oxygen content in the inlet charge will result in unburnt
fuel and lotsa smoke
If you are going to "neutralise" the EGR you are far better off
putting in a blanking plate in the fitting on the exhaust manifold,
just pulling the plugs on the control valve can still result in the
EGR stuck open - and potentially life threatening fuel consumption
on the CSR.
If you use biodiesel then you can probably put your hand on
your heart and neutralise the EGR as biodiesel burns at a lower
temperature and is a much more effective way to avoid producing
nitrides
ttfn
Matthew
bogged from wikipedia...
EGR in Spark-Ignited (SI) Engines
In a typical automotive SI engine, 5 to 15 percent of the exhaust gas is routed back to the intake as EGR (thus comprising 5 to 15 percent of the mixture entering the cylinders). The maximum quantity is limited by the requirement of the mixture to sustain a contiguous flame front during the combustion event; excessive EGR in an SI engine can cause misfires and partial burns. Although EGR does measurably slow combustion, this can largely by compensated for by advancing spark timing. Contrary to popular belief, EGR actually increases the efficiency of gasoline engines via several mechanisms:
Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses. fqf
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC, rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is relatively minor compared to the first two.
EGR is typically not employed at high loads because it would reduce peak power output, and it is not employed at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle.
[edit]
EGR in Diesel Engines
In modern diesel engines, the EGR gas is cooled through a heat exchanger to allow the introduction of a greater mass of recirculated gas. Unlike SI engines, diesels are not limited by the need for a contiguous flamefront; furthermore, since diesels always operate with excess air, they benefit from EGR rates as high as 50% (at idle, where there is otherwise a very large amount of excess air).
Since diesel engines are unthrottled, EGR does not lower throttling losses in the way that it does for SI engines (see above). However, exhaust gas (largely carbon dioxide and water vapor) has a higher specific heat than air, and so it still serves to lower peak combustion temperatures; the diesel engine's efficiency is still improved by reduced heat rejection and dissociation.
[edit]
Implementation of EGR
Recirculation is usually achieved by piping a route from the exhaust manifold to the inlet manifold, which is called external EGR. A control valve (EGR Valve) within the circuit regulates and times the gas flow. Some engine designs perform EGR by trapping exhaust gas within the cylinder by not fully expelling it during the exhaust stroke, which is called internal EGR.
EGR can also be used by using a variable geometry turbocharger (VGT) which uses variable inlet guide vanes to build sufficient back pressure in the exhaust manifold. For EGR to flow, a pressure difference is required across the intake and exhaust manifold and this is created by the VGT.
Other methods that have been experimented with are using a throttle in a turbocharged diesel engine to decrease the intake pressure to flow EGR.
Early EGR systems were unsophisticated affairs utilizing manifold vacuum as the only input to an on/off EGR valve; reduced performance and/or drivability were common side-effects. However, modern systems utilizing electronic engine control computers, multiple control inputs, and servo-driven EGR valves typically improve performance/efficiency with no impact on drivability. In the past, a meaningful fraction of car owners disconnected their EGR systems. Some still do either because they believe EGR reduces power output or because they feel the environmental intentions of EGR are misguided. Disconnecting an EGR system is usually as simple as unplugging an electrically-operated valve or inserting a ball bearing into the vacuum line in a vacuum-operated EGR valve. In all cases, the EGR system will need to be operating normally in order to pass emissions tests.
EGR in Spark-Ignited (SI) Engines
In a typical automotive SI engine, 5 to 15 percent of the exhaust gas is routed back to the intake as EGR (thus comprising 5 to 15 percent of the mixture entering the cylinders). The maximum quantity is limited by the requirement of the mixture to sustain a contiguous flame front during the combustion event; excessive EGR in an SI engine can cause misfires and partial burns. Although EGR does measurably slow combustion, this can largely by compensated for by advancing spark timing. Contrary to popular belief, EGR actually increases the efficiency of gasoline engines via several mechanisms:
Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses. fqf
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC, rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is relatively minor compared to the first two.
EGR is typically not employed at high loads because it would reduce peak power output, and it is not employed at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle.
[edit]
EGR in Diesel Engines
In modern diesel engines, the EGR gas is cooled through a heat exchanger to allow the introduction of a greater mass of recirculated gas. Unlike SI engines, diesels are not limited by the need for a contiguous flamefront; furthermore, since diesels always operate with excess air, they benefit from EGR rates as high as 50% (at idle, where there is otherwise a very large amount of excess air).
Since diesel engines are unthrottled, EGR does not lower throttling losses in the way that it does for SI engines (see above). However, exhaust gas (largely carbon dioxide and water vapor) has a higher specific heat than air, and so it still serves to lower peak combustion temperatures; the diesel engine's efficiency is still improved by reduced heat rejection and dissociation.
[edit]
Implementation of EGR
Recirculation is usually achieved by piping a route from the exhaust manifold to the inlet manifold, which is called external EGR. A control valve (EGR Valve) within the circuit regulates and times the gas flow. Some engine designs perform EGR by trapping exhaust gas within the cylinder by not fully expelling it during the exhaust stroke, which is called internal EGR.
EGR can also be used by using a variable geometry turbocharger (VGT) which uses variable inlet guide vanes to build sufficient back pressure in the exhaust manifold. For EGR to flow, a pressure difference is required across the intake and exhaust manifold and this is created by the VGT.
Other methods that have been experimented with are using a throttle in a turbocharged diesel engine to decrease the intake pressure to flow EGR.
Early EGR systems were unsophisticated affairs utilizing manifold vacuum as the only input to an on/off EGR valve; reduced performance and/or drivability were common side-effects. However, modern systems utilizing electronic engine control computers, multiple control inputs, and servo-driven EGR valves typically improve performance/efficiency with no impact on drivability. In the past, a meaningful fraction of car owners disconnected their EGR systems. Some still do either because they believe EGR reduces power output or because they feel the environmental intentions of EGR are misguided. Disconnecting an EGR system is usually as simple as unplugging an electrically-operated valve or inserting a ball bearing into the vacuum line in a vacuum-operated EGR valve. In all cases, the EGR system will need to be operating normally in order to pass emissions tests.
Plugged mine back in this morning before coming to work as I didn't notice any real difference over the last few days......also didn't notice any huge fuel consumption issues either like some others.
Anyway, as there was no noticable difference or advantage from removing the plug, I'll be keeping mine plugged in.
Cheers for the input though....at least I know where the EGR unit is under my bonnet :lol:
Anyway, as there was no noticable difference or advantage from removing the plug, I'll be keeping mine plugged in.
Cheers for the input though....at least I know where the EGR unit is under my bonnet :lol:
snip
Hmm this is interesting. I think my EGR connection fell off, & the back of the car is sooty. I putthe smoking down to the chip, maybe its time for some further investigation...
Regards
Max P
end snipmattD110td5x wrote: If the EGR is stuck open when the engine is cold or at low revs
then low oxygen content in the inlet charge will result in unburnt
fuel and lotsa smoke
Hmm this is interesting. I think my EGR connection fell off, & the back of the car is sooty. I putthe smoking down to the chip, maybe its time for some further investigation...
Regards
Max P
Stereo by Simex!
MaxMaxtd5def wrote:snipend snipmattD110td5x wrote: If the EGR is stuck open when the engine is cold or at low revs
then low oxygen content in the inlet charge will result in unburnt
fuel and lotsa smoke
Hmm this is interesting. I think my EGR connection fell off, & the back of the car is sooty. I putthe smoking down to the chip, maybe its time for some further investigation...
Regards
Max P
I have the chip and this will result in more smoke out the back. I then unplugged the EGR unit - as mentioned above - and even more black smoke appeared - I was expecting this though.
I also removed my resonator recently and added a turndown to the end of the exhaust pipe......this IMO is a great way to avoid soot on the back on your car...if positioned correctly obviously.
Aye, Mick
infact I avoid the supermarkets and buy from the butchers, the joy of living in a decent location I guess.tim wrote:This is a new religion here in the UK! Not defending any of the commercial parties involved. But amazed how many people over here seem to need a meaning in their lives.tony cordell wrote:Scrapiron are to be avoided at all costs
the copy other products and rip them off as their own
Wonder if they all wear T-shirts and make stickers to defend their local butcher against the big supermarkets?
They need to get out more.
Tim
then not buying inferior crap from rip off merchants satisfies myself.
another scrapiron employee per chance?
Defender 90 Modified
Defender 110XS Standard
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Defender 110XS Standard
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start here:
http://forums.lr4x4.com/index.php?showtopic=4300&hl=
Then here:
http://www.devon4x4.com/forum/viewtopic.php?t=1252
That should cover it nicley
http://forums.lr4x4.com/index.php?showtopic=4300&hl=
Then here:
http://www.devon4x4.com/forum/viewtopic.php?t=1252
That should cover it nicley
Defender 90 Modified
Defender 110XS Standard
[url=http://www.lr4x4.com]lr4x4.com[/url]
Defender 110XS Standard
[url=http://www.lr4x4.com]lr4x4.com[/url]
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