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Discussion Starter #1
I'm looking to get my car remapped soon. I've been tossing and turning on whether to get the EGR blanked off or to leave it well alone.

I've spent hours researching and searching all the posts on here (and typeaccord). Relics topic was an eye opener as to how much power the EGR wastes. Some people report an improved economy whilst others see no difference. Would be grateful if someone who has had theirs blanked off (or via software) could shed light on this.

Forget a moment about the whole environmental aspect for a second and its much easier to draw up a comparison of pros and cons. My understanding is that the EGR allows the engine to heat up faster, can anyone who's blanked theirs off confirm this is the case as their car takes longer to get to opperating temp?

It would be a very good idea indeed if a remap outfit could create a dynamic state for the EGR. It would remain on until the engine was warm, then off after that as it serves no real purpose.

EGR's fail eventually and my car is approaching 100k so it's a matter of time really, since I'm getting a remap it would make sense to do the EGR now but I am hesitant for some reason.

I know Honda have worked the EGR pretty well into the whole engine design and no doubt people will be of the opinion that Honda know what they're doing etc...but if they had a choice of adding an EGR or not then no doubt they would have foregone its addition, just like all manufacturers did before the legislative crackdown on NOX and emmisions.

Your thoughts?
 

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EGR doesn't help the engine to warm up. It replaces fresh intake air with exhaust gases to reduce the available oxygen, and so reduce the amount of NOx produced.
 

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Discussion Starter #3
If fresh (cold) intake is being replaced with (warm) exhaust gasses then surely that would help to heat it up?
 

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I'm running an EGR off remap, mainly because my valve was on the fritz.

I went from stage 1/EGR on to stage 2/EGR off and noticed improved economy. The first maps was from Celtic and the second from Premier/Elite.

I ran Torque on both maps and couldn't say I noticed the engine warming up any quicker. There are too many variables in life and I'm no lab rat

I also decoked my entire inlet so EGR off made sense to keep it cleaner.

MOT tests easily passed with EGR off, with it on passing was marginal.

Visually my car no longer pumps out visible particulate under high loads. So it's been an all round positive move for me.
 

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But it WILL be pumping out a lot more NOx. And that is becoming taken very seriously... Future MOTs will no doubt monitor for this, especially in light of the related VW scandal.
 

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Discussion Starter #7
Yeah, I've seen the thread on typeaccord regarding cleaning the inlet. Not something I'd be comfortable doing myself, and considering I work 7 days a week I can't soak in Mr muscle/coke overnight as I need my car everyday.

I was going to clean out the EGR but there's no point in I'm getting it blanked off.

What sort of MPG gains have you seen?
 

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Discussion Starter #8
But it WILL be pumping out a lot more NOx. And that is becoming taken very seriously... Future MOTs will no doubt monitor for this, especially in light of the related VW scandal.
I have also heard this, but I feel it's likely they will only bother on the newer cars. Euro 4 cars for example will pump out much more NOX than a Euro 6 so either they have different max NOX output limits for Euro 3/4/5/6 or they make it compulsory on all cars registered after 2015, which will be Euro 6.
 

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True. Does anyone know by how much?

My remapped, EGR off passes the current test with the same test figure as a non mapped, EGR on car.

Remaps adjust the AFR characteristics to work without the EGR valve. So it's not as simple as just bypassing the exhaust valve.

The operation of an EGR valve WILL clog your inlet. This WILL adversely affect the engines ability to breath. This should be factored in on older, poorly maintained engines. They will not be as efficient and pollute more.
 

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If you are keeping your EGR on, then decoke when you like.

A pukka rolling road remap should benefit from a decoke shortly before.

If you plan to blank the EGR, then decoke it afterwards/at the same time. If you decoke before then your inlet will get deposit build up until you get around to blanking.

How coked up your inlet is depends on use/miles. You can get an idea whilst cleaning your EGR valve/at least pop it off.
 

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Discussion Starter #13
If you are keeping your EGR on, then decoke when you like.

A pukka rolling road remap should benefit from a decoke shortly before.

If you plan to blank the EGR, then decoke it afterwards/at the same time. If you decoke before then your inlet will get deposit build up until you get around to blanking.

How coked up your inlet is depends on use/miles. You can get an idea whilst cleaning your EGR valve/at least pop it off.
I cleaned my EGR valve a month or so ago using the guide from this forum. It was pretty bad. I'd say the aperture was 50% clogged
 

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There is no current emissions test on diesels, merely a subjective smoke test.
The current test is not subjective, it is objective. The vehicle test needs to meet a measured standard, not an arbitrary figure.
 

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I cleaned my EGR valve a month or so ago using the guide from this forum. It was pretty bad. I'd say the aperture was 50% clogged
It's scary how the valve gunks up.

For comparison, my valve was less than 50% clogged and my inlet had well over 5mm off goo lining the chambers.

The inlet build up was greater near the valves/cylinder head.

Old school engine tunning focused on air flow, this goo must be terrible for restricting air flow.
 

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The opacity test does have figures, but the application is poorly controlled. Overall, I'd call the test subjective, given the variance that can be introduced by the particular tester. But, crucially, NOx is not monitored.
 

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The MOT smoke test is rather pointless really… mine still passes even though it is very clearly generating more smoke than the stock car… It's worth noting that EGR off won't affect it since the EGR valve only opens at part throttle and the test is done using WOT.

I've also noticed people getting an EGR off map and not blanking/disabling the valve… The valve still works on an EGR off map, the only thing that gets changed in the map is the hysterisis maps - so that the ECU doesn't throw a CEL when the EGR valve doesn't respond as it should. I'm currently of the opinion that the people saying EGR off doesn't make a difference to performance haven't actually disabled/blanked the EGR valve off to stop it working.

And yes, NOx is an issue… it'll be interesting to see how they go about testing it… ;)
 

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The egr off map disables the egr from opening, however by design it will always ben open 4.7%. And that tiny bit of exhaust gas trickling into the intake manifold is plumbed in after the MAF and MAP sensors, so it kind of enters undetected by the ecu, hence the advice by tuners to physically blank off.

I've had it a while now and there is no difference in mpg from before the map and blank. I think a egr off remap will be better for power than a egr on remap.
The engine does take a touch longer to warm up to if the egr is blanked so economy will suffer if your doing short trips
 

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Discussion Starter #20
The egr off map disables the egr from opening, however by design it will always ben open 4.7%. And that tiny bit of exhaust gas trickling into the intake manifold is plumbed in after the MAF and MAP sensors, so it kind of enters undetected by the ecu, hence the advice by tuners to physically blank off.

I've had it a while now and there is no difference in mpg from before the map and blank. I think a egr off remap will be better for power than a egr on remap.
The engine does take a touch longer to warm up to if the egr is blanked so economy will suffer if your doing short trips
I work nearby 4-5 days a week - around 2.5 miles away
The other 2 days a week I work around 30 miles away
Around once a month I pop down to see family - who are 120 miles away

Considering most of the time i'm doing short journeys, I suppose i'm likely to see a slight drop in MPG?
 
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