Patrol 3.0Di EGR Valves
Submitted: Saturday, Aug 12, 2006 at 10:24
ThreadID:
36710
Views:
4608
Replies:
4
FollowUps:
12
This Thread has been Archived
Chaz
Following up on Post No.36378, I decided to block off my EGR port to the inlet manifold in the way that “hl & Phil12345” suggested and I thought that some of you may be interested in my results. Although it’s only been done for a couple of days now, I have tried to vary my driving style to cover as many situations that one may come across, although I haven’t yet had the opportunity to do any towing or high speed driving.
My 3.0Di Patrol has a Dtronic fitted with boost and EGT gauges and also sports a manual converter lock.
My findings to date are quite remarkable to say the least. On hills that normally bought my turbo up to 350DegC are now at 250C. When pulling up at traffic lights, the turbo would cool down to 200C in about a minute. Normal flat driving, around 250C and accelerating away it would go to 300C. Now, with the EGR blocked off, it generally runs around 100DegC cooler. Idling at traffic lights it now goes down to 100C and driving away to 200C. Driving on a flat road, it runs anywhere in between.
There is also a noticeable increase in torque in the lower rev range and from as far down as 1500rpm it pulls hard without any protest where previously 1700 would have been my lower limit.
I’m not sure of the long term consequences of doing this, but if it doesn’t affect fuel economy and helps improve engine life, it must be worth looking into. I’m certainly not suggesting that everyone should do it, but for those that have you may be assured that it hasn’t increased your EGT’s.
Chaz
Reply By: Member - Andrew W (SA) - Saturday, Aug 12, 2006 at 10:28
Saturday, Aug 12, 2006 at 10:28
and if you run Biodiesel you can even feel happy that you are not polluting the air we breathe as much ;-)
AnswerID:
188648
Follow Up By: Member - Jeff M (WA) - Saturday, Aug 12, 2006 at 11:04
Saturday, Aug 12, 2006 at 11:04
Amen!
I had to put my first 15L of Dino Diesel in after over 10,000km's of driving on B100 yesterday (very upsetting!). I used too much BD this month and my delivery is not due till Wed so I had to put $20 bucks in at the servo. Amazing, after 3 starts it was back to blowing a big puff of BLACK smoke on startup, and I'm only running 50/50 mix at the mo!
But back on track, those results are fantastic news for ZD30 owners IMHO. I don't have an EGT guage, but I was certainly sure that the surf was running cooler up long hills on my mechanical
water guage after I blocked the EGR. I guess it does't have to work as hard... Personally I was expecting the temp to go up as the combustion temp would have been higher, but I guess all the other benefits like a cooler running turbo and less exaust heat in the block outway that problem. I actually feel better after reading your results even though I've had
mine blocked off for over 18 months.
With those kinds of drops in EGT's, anyone towing reguarly should deffinatly block it off IMO.
FollowupID:
445922
Follow Up By: Chaz - Saturday, Aug 12, 2006 at 17:08
Saturday, Aug 12, 2006 at 17:08
Hi Andrew and Jeff,
I would imagine that the ZD30 is a very clean burning engine, and so far I haven’t noticed any changes in exhaust discharge although having said that, I wouldn’t know if there was any significant change to the composition. To my knowledge the majority of diesel exhaust is soot and carbon dust that falls to the ground and the toxins are minimal compared to petrol exhaust emissions. Certainly something to look out for, but in the short term my engine life is more of a concern to me.
Cheers,
Chaz
FollowupID:
445956
Follow Up By: Member - Jeff M (WA) - Saturday, Aug 12, 2006 at 17:19
Saturday, Aug 12, 2006 at 17:19
The EGR's sole purpose is to lower combustion temp's in order to produce less CO2, nothing to do with soot or any of the other nasties. You can't see the CO2 so it would be impossible without the right test gear to tell if it was producing more now, one would assume so however. Biodiesel if you look at the whole life cycle produces 75% less CO2 than regular DinoDiesel so by disabling your EGR and running BD you'd still be producing less CO2 than if you had your EGR fired up and DinoDiesel in the
tank.
But I disabled
mine before I ran BD anyway, so not having a go, just food for thought.... Or should that be food for fuel? LOL
FollowupID:
445960
Follow Up By: pilbaradisco - Sunday, Aug 13, 2006 at 00:29
Sunday, Aug 13, 2006 at 00:29
Not CO2, Nitrogen Oxides!
The purpose of EGR (Exhaust Gas Recirculation) is to reduce the NOx emissions. Air is mainly made of oxygen and nitrogen (O2 and N2). At temperatures above 1300°C (2372°F), these molecules split apart and rejoin with each other to make nitrogen oxides (like NO, NO2, etc...). The nitrogen oxides contribute to smog formation.
EGR puts a portion of the exhaust gas back into the intake manifold, so it mixes with the fuel and air. (Note that the exhaust adds to the fuel and air; it doesn’t replace any of it). The added mass in the cylinder is harder to heat up, so the combustion events have lower peak temperatures. The lower temperatures prevent the O2 and N2 from splitting and combining. Even though the exhaust is hot, about 600°C (or 1112°F), it's much cooler than the 1300°C required to make NOx.
In summary, the exhaust adds mass, increasing the heat capacitance of the mixture (i.e. making it harder to heat up the mixture in the cylinder). Peak temperatures are lower, reducing NOx formation, which ultimately reduces smog in the environment.
Glen.
FollowupID:
446002
Follow Up By: Chaz - Sunday, Aug 13, 2006 at 07:26
Sunday, Aug 13, 2006 at 07:26
Thanks Glen. A very accurate summary of how the EGR system works and why. This is why I’ve always thought that it is merely an emission control system. As you have explained, it keeps peak combustion temps down but I’m supprised how much cooler the exhaust temp is without it.
Cheers
Chaz
FollowupID:
446011
Follow Up By: Member - Hugh (WA) - Sunday, Aug 13, 2006 at 23:21
Sunday, Aug 13, 2006 at 23:21
Hi Glen,
What you've stated is close on the money. NOx reduction is the main reason for EGR, however the EGR does display the air, not add to it. EGR is enert therefore doesn't combust and the reduced amount of air (i.e. less N2 and O2) results in the formation of less NOx. Also other effects such as burn rate, peak temps, etc but reducing NOx as you've highlighted is the end result.
For gasoline engines, addition of EGR not only reduces NOx but also allows the engine to run less throttled, thereby increasing manifold pressure, reducing pumping work which allows for improved fuel economy. I don't have too much diesel cal experience but I expect that in unthrottled applications effect on fuel economy not so pronounced.
Regards,
Hugh
FollowupID:
446130
Reply By: Member - Hugh (WA) - Saturday, Aug 12, 2006 at 11:05
Saturday, Aug 12, 2006 at 11:05
Hi Chaz,
Thanks for the feedback and most importantly for providing some factual data. I'll be interested to know the influence on fuel economy once you've done enough driving to get some meaningful figures.
Regards,
Hugh
PS I haven't done the torque converter mod yet but it's on my to-do list.
AnswerID:
188652
Follow Up By: Chaz - Saturday, Aug 12, 2006 at 17:10
Saturday, Aug 12, 2006 at 17:10
Hi Hugh,
I emphasized my converter lock because I feel that with an auto, it gives me a slightly more consistent base to work with. By eliminating converter flare I can maintain a constant speed at certain revs and maintain the load so that the testing becomes a little more consistent than it would be if the revs and load were to change constantly.
This way it works just like a manual transmission.
Unfortunately it will probably be some weeks before I’ll be able to compare fuel usage, but I will let the
forum know if there are any significant changes.
Let me know if you need any help with the circuit.
Chaz
FollowupID:
445957
Reply By: hl - Saturday, Aug 12, 2006 at 15:12
Saturday, Aug 12, 2006 at 15:12
Hi Chaz,
Very interesting indeed. I my searches about the likely effect I came across an interesting statement by someone who sounded like he knew what he was talking about. He said that the addition of exhaust gas obviously reduces peak combustion temperatures, but that does not mean average cylinder temps and as a consequence, EGT will be lower. Your findings seem to agree.
The other aspect of course is deposits in the intake. I replaced a gasket on my EGR valve today and had to pull the pipe right off, so it gave me a chance to look (and feel) inside the inlet manifold where the EGR pipe connects. It wasn't a pretty sight, lots of gunk is starting to accumulate in there, and my truck hasn't even done 70,000.
Anyway, I will be interested to hear more.
Cheers
AnswerID:
188674
Follow Up By: ACDC - Saturday, Aug 12, 2006 at 15:27
Saturday, Aug 12, 2006 at 15:27
It's amazing the crap that builds up in the manifold.
FollowupID:
445945
Follow Up By: hl - Saturday, Aug 12, 2006 at 15:43
Saturday, Aug 12, 2006 at 15:43
Hi again, Chaz
You did not mention boost readings. One of the concerns I have is whether the boost at medium revs and load when the EGR valve is open, is higher now. Since the portion of exhaust gas that diverted back to the inlet now drives the turbo a bit harder. I wonder if there is a noticable difference.
Cheers
FollowupID:
445946
Follow Up By: Chaz - Saturday, Aug 12, 2006 at 17:10
Saturday, Aug 12, 2006 at 17:10
Hi hl,
No sure if it’s my imagination or not, but the boost gauge seems to react a bit quicker although the readings haven’t noticeably changed. On one of the hills that I tested it on I always maintained around 10psi doing 60km/h at just under 2000rpm and the temp would always go to 350DegC regardless of outside temp and weather. Now at the same speed, same gear and same boost pressure I’m getting 250DegC and it seems to have a bit more pull up the
hill. I wonder if the extra torque is helping to keep the temp down because it does it with less effort, but that doesn’t explain the lower temps at idle.
I get the feeling that the boost is controlled a little easier with the right foot and doesn’t tend to wander all over the place as much. Anyone that has a boost gauge would know what I mean because the ZD30 has some strange characteristics when it comes to boost unlike any “normal” turbo car where the boost levels are a little more proportional to throttle input and load.
I’ll keep a closer eye on my boost gauge in my travels tonight and let you know if there are any significant changes.
Chaz
FollowupID:
445958
Reply By: Snowy 3.0iTD - Monday, Aug 14, 2006 at 12:00
Monday, Aug 14, 2006 at 12:00
Chaz
Where exactly did you block yours, upstream or downstream of the actual valve, I have worndered whether this would have any effect on the engine management computer?
Other than the manufacturer possibly trying to use it as an excuse to wiggle out of a warranty claim, has anyone heard or had any negatives on doing this, as I am contemplating getting my mechanic to do it next service.
Cheers
Snowy
AnswerID:
188908
Follow Up By: hl - Monday, Aug 14, 2006 at 14:14
Monday, Aug 14, 2006 at 14:14
Hi,
The easist place to do it, especially if you just want to try it, is where the EGR pipe bolts to the inlet manifold. Undo the 2 bolts and pull the pipe back a fraction. The existing gasket will then just fall out and you can use it as a template for the block.
No need to cut the centre hole :).
Cheers
FollowupID:
446223
Follow Up By: Chaz - Monday, Aug 14, 2006 at 19:43
Monday, Aug 14, 2006 at 19:43
Hi Snowy,
I took hl’s advice and made up a plate to replace the stainless gasket on the inlet manifold end of the alloy tube. The only difference is that I made it from 16gauge steel and ran it over a surface grinder before fitting it without any gasket sealer. I couldn’t see how I could get it in without removing the pipe if I used a sealer on it.
As far as the ECU goes, I guess that it would still control the EGR valve, but nothing would come through, and without an oxygen sensor on the exhaust, it shouldn’t make any difference.
So far, on this and the Patrol4x4
forum that I monitor, I haven’t heard of any adverse effects from doing this. I guess only time will tell, but I feel that doing something is better than just sitting around and waiting for it to go (bang) considering the uncertainty in this model.
Chaz
FollowupID:
446287