Lacozcorby
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did you just blank it without telling anything to ECU ???
EGR Valve Removal + Clean
- Thread starter 2taol
- Start date
Jan Accord
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I went to an local tuner to turn off the EGRLacozcorby said:
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accord1108
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Im asking this purely for information, why were egrs fitted to begin with, what was the thought behind them, is it purely emmision reduction?F6HAD said:
freddofrog
won 16.4k on Euro lottery :)
I think I've seen you say that before Fahad, but in the interests of pedantism, the aim is to reduce combustion temperature under specific load conditions (in the official emission test driving cycle). By reducing combustion temperature, the amount of NOx is reduced.F6HAD said:
All diesel engines run at varying levels of lean (i.e. oxygen rich) and lean-burn causes combustion temperature to rise, which causes increased production of NOx (this is true for any combustion of any fuel). It seems counter-intuitive to suggest that bringing exhaust gas back into the combustion chamber will reduce combustion temperature, but it achieves this by reducing the amount of oxygen in the combustion, thereby reducing combustion temperature, thereby reducing the amount of NOx during the burn.
Yes mate I know how a Diesel engine works, and whichever way you explain it and the logic behind it, the aim is reduce emissions.
And it works, when you have a perfectly clean inlet and perfectly operating EGR valve. However once they get coked up, the fuel air mix is not maintained and they actually have the opposite effect.
Bottom line is they're a bad idea. Most car owners just want reliable engines. They don't want to get their hands dirty and have to remove EGR valves and intake manifolds to clean them out every few months.
Most EGR valves start leaking after a few years anyway as the valve operation loses its efficiency.
And it works, when you have a perfectly clean inlet and perfectly operating EGR valve. However once they get coked up, the fuel air mix is not maintained and they actually have the opposite effect.
Bottom line is they're a bad idea. Most car owners just want reliable engines. They don't want to get their hands dirty and have to remove EGR valves and intake manifolds to clean them out every few months.
Most EGR valves start leaking after a few years anyway as the valve operation loses its efficiency.
freddofrog
won 16.4k on Euro lottery :)
Don't worry, I'm not considering whether EGR removal/delete is good or bad, I'm just interested in being pedantically correct about why EGR is there (on any IC engine). EGR is definitely not an attempt to "recycle unburnt gases", it's an attempt to reduce O2 in the combustion, thereby reducing combustion temperature, thereby reducing NOx (on a diesel engine), and reducing the danger of knock (on a petrol engine). The fact that EGR draws soot back into the inlet system is its actual downside, not its intention.
edit: btw, this thread is still is very good DIY for those that want to keep the EGR on the engine
edit: btw, this thread is still is very good DIY for those that want to keep the EGR on the engine
You're mixing a lot of things up there mate. EGR on a petrol and diesel serve different purposes and implementation of EGR varies between manufacturers and models.
In any case yes the ultimate aim is to reduce emissions, and how it does that is by recirculating dirty exhaust gasses to cool inlet temps and thereby reducing nox.
Newer cars like my audi actually have specific nox sensors in the exhaust and use a urea additive to reduce them further.
They're all flawed designs however. EGR's, DPF's and all these add-on's are simply trying to reduce emissions to play the European car regs compliance game.
They can't make a Diesel engine 'clean' so they have to try and reduce the volume of harmful gasses and particulates that are emitted.
I wish they would spend time and money checking cars that are 24+ months old and ***ess them for their real world emissions. It would be clear how real world conditions are completely different from a brand new car in a lab.
I accept your point however, an EGR's function may be to recycle exhaust gasses but it's purpose is to reduce emissions.
In any case yes the ultimate aim is to reduce emissions, and how it does that is by recirculating dirty exhaust gasses to cool inlet temps and thereby reducing nox.
Newer cars like my audi actually have specific nox sensors in the exhaust and use a urea additive to reduce them further.
They're all flawed designs however. EGR's, DPF's and all these add-on's are simply trying to reduce emissions to play the European car regs compliance game.
They can't make a Diesel engine 'clean' so they have to try and reduce the volume of harmful gasses and particulates that are emitted.
I wish they would spend time and money checking cars that are 24+ months old and ***ess them for their real world emissions. It would be clear how real world conditions are completely different from a brand new car in a lab.
I accept your point however, an EGR's function may be to recycle exhaust gasses but it's purpose is to reduce emissions.
freddofrog
won 16.4k on Euro lottery :)
well I do say in #37 "thereby reducing NOx (on a diesel engine), and reducing the danger of knock (on a petrol engine)"F6HAD said:
But this thread is primarily about EGR on the Honda diesel engine
I'm not sure why you say "recirculating dirty exhaust gasses to cool inlet temps and thereby reducing nox" , it doesn't matter whether the exhuast is "dirty" or not, and it's not to cool inlet temps, it's to reduce the amount of O2 in the combustion chamber when the burn takes place, which reduces the production of NOx. There is basically less O2 in the exhaust gas which is why it is recirculated, thereby reducing the amount of O2 in the combustion chamber.F6HAD said:
There is no doubt that when a car leaves the factory it meets the emission specs that it is designed for (unless it was using the infamous "cheat" code) but yes, after then, it's downhill all the way as far as emissions are concerned and EGR on a diesel can actually accelerate the deterioration of other factors that will cause an increase in emissions and decrease in power and mpg.F6HAD said:
edit: the damned "post editor" is weird when quoting more than two times
Yes mate you're right, slightly bad choice of words on my part. I can see that when reading it back. I should have been clear to say that they reduce the level of o2 as a lot of it is already burnt in the first cycle.
In my mind when I say recycle dirty gasses that's all I mean, they are attempting to burn them again.
All I would say is that theory is great, but in practise recycling the 'dirty' gasses are what cause the problems. This is why petrol engines don't suffer the same running issues with EGR valves as diesels, their gasses are not filled with sooty oily particles.
I also know from firsthand experience that EGR valves play a different role in certain applications such as relieving excess boost pressure. I'm sure I've pointed this out in a previous post.
In any case thank you for clearing it up and drawing the distinction between an EGR's actual mechanical function and it's intended purpose as part of the emissions cycle.
In my mind when I say recycle dirty gasses that's all I mean, they are attempting to burn them again.
All I would say is that theory is great, but in practise recycling the 'dirty' gasses are what cause the problems. This is why petrol engines don't suffer the same running issues with EGR valves as diesels, their gasses are not filled with sooty oily particles.
I also know from firsthand experience that EGR valves play a different role in certain applications such as relieving excess boost pressure. I'm sure I've pointed this out in a previous post.
In any case thank you for clearing it up and drawing the distinction between an EGR's actual mechanical function and it's intended purpose as part of the emissions cycle.
freddofrog
won 16.4k on Euro lottery :)
One has to "love" pedantism to persevere with it in a discussion, it can sometimes lose one some friends LOL
I suppose if one retained and cleaned the EGR and the inlet manifold every year on the 7th gen diesel, it would help NOx emissions in the world by about 0.1% at traffic lights, maybe there's a research grant in establishing that percentage. I say traffic lights because otherwise, the EGR is likely to be shut in real world driving anyway. If one doesn't clean the EGR and inlet manifold every year, things becomes more and more counter productive for real world driving. The permanent solution is to stop the sooty oily particles getting into the inlet in the first place
I suppose if one retained and cleaned the EGR and the inlet manifold every year on the 7th gen diesel, it would help NOx emissions in the world by about 0.1% at traffic lights, maybe there's a research grant in establishing that percentage. I say traffic lights because otherwise, the EGR is likely to be shut in real world driving anyway. If one doesn't clean the EGR and inlet manifold every year, things becomes more and more counter productive for real world driving. The permanent solution is to stop the sooty oily particles getting into the inlet in the first place
freddofrog
won 16.4k on Euro lottery :)
mind you, if they'd fitted an easily accessible filter that collected the soot and let only the gas into the inlet, that way O2 % reduced and no deterioration ....I should have got a job in Japan at Tochigi and made Honda diesel engines even better LOL
So basically a separate DPF for the inlet side lol
Or they could fit a bypass after the DPF back to the inlet.
There's probably good reason why they do and don't do certain things. I'm not a cynic by nature but a part of me has to question whether it's in their interest to make cars so reliable that they only need a dealer visit for routine servicing
Or they could fit a bypass after the DPF back to the inlet.
There's probably good reason why they do and don't do certain things. I'm not a cynic by nature but a part of me has to question whether it's in their interest to make cars so reliable that they only need a dealer visit for routine servicing
freddofrog
won 16.4k on Euro lottery :)
This is getting interesting, but I'm also a cynic by nature, so sadly I cannot refute what you say LOL
Grayedout
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Just a quick one related to the EGR valve; I have been monitoring my engine through a monitoring app. I have noticed the "EGR commanded" and "EGR error" sensors read 49,41% and 3,91% respectively. Does that mean it`s a good time for a blank off and a remap?
freddofrog
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what year is your car ?DiD said:
freddofrog
won 16.4k on Euro lottery :)
On the pre-facelift diesel models the EGR valve is a simple on/off solenoid i.e. either open or shut. But the flow through the EGR is controlled by employing Pulse-Width-Modulation of a low frequency square-wave on the solenoid. The ECU also uses the drop-off in MAF as the closed-loop target for the EGR. There will obviously be a fair bit of lag and 'hunting' which will represent an error between the demanded and actual figures, and it's these values which you are probably reading from the Bosch EDC16 ECU.
In any closed-loop system like this there will always be some error between commanded and actual targets, and without comparing the values for "EGR commanded" and "EGR error" with a system that has clean inlet manifold (etc), it's difficult to know if 49,41% and 3,91% are reasonable or not. Note that it might also depend on whether those values are averages and how they are averaged.
In any closed-loop system like this there will always be some error between commanded and actual targets, and without comparing the values for "EGR commanded" and "EGR error" with a system that has clean inlet manifold (etc), it's difficult to know if 49,41% and 3,91% are reasonable or not. Note that it might also depend on whether those values are averages and how they are averaged.
Couple of questions on this topic:
1. Can a remap completely deactivate the EGR valve so it stays closed all the time and won't need a banking plate?
2. how much does a remap for this cost in the UK? (I'm trying to get an idea so I can approach a local remapping service with at least a base price)*
*I could of course air mail my ECU to a UK tuner with N22 experience..
1. Can a remap completely deactivate the EGR valve so it stays closed all the time and won't need a banking plate?
2. how much does a remap for this cost in the UK? (I'm trying to get an idea so I can approach a local remapping service with at least a base price)*
*I could of course air mail my ECU to a UK tuner with N22 experience..
Yes we can deactivate software only and initially this is how we were doing them for years. However these cars have a common problem with EGR leak so even when the software is requesting the valve to stay closed, some gasses still get through and the unexpected air registered causes smoking issues.
If you drop me a line with your location I'll give you a price, uk or not.
If you drop me a line with your location I'll give you a price, uk or not.