Mitsubishi Delica Owners Club UK™

[Rusty]

I've been reading the debate over in the Pocuk Tech forum.
http://www.pocuk.com/forums/viewtopic.php?t=25605&start=105 (Page 8 )
It is a debate about the use of the blanking plate on the EGR valve. Now I'm not a mechanic nor do I want to start a technical debate on this forum, but it has opened my eyes to something I had not thought about.

I think our very own PeteMillis gives the best description of the problem etc on page 8 I think. If I read his post right, this advice says that if a EGR is fitted then it is wise to make sure your fuel pump is turned down slightly. (To put it in simple terms). I'm I right? If so, how much?

I for one am seriously thinking of removing my plate and having a go at cleaning the valve and putting it all back to the way Misubishi intended.

Although to be fair, I don't think I'm in any trouble as from what I gather it is only an issue if the engine is put under constant strain, i.e. hard acceleration and hi speeds etc. I find myself that the Deli does not take to this kind of treatment neither does my wallet . But even so is it worth the risk for the sake of spending some time cleaning the valve. (I appreciate this is easier said than done on a L300 )

I hope someone is able to get a definative answer from Mits HQ
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[Google]

[Ginja Nutz]

Phew... my brain aches !!!

Good reading - It's taken nearly an hour with all the detour threads and articles !

I think I might take the blanking plate out and give it a try again (it's been in there for over 18 mths / 8000 miles).

Now all I gotta do is find the original gasket again

Gary
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Any information in this posting is correct to the best of my knowledge and I accept no resposibilty for any actions or results based upon it.©

[Pajeropah]

Must admit I never saw any conclusive difference when I fitted the blanking plate to my Deli and am now wondering whether or not to remove it. Especially as it didn't smoke when I first had it!! Mine has now done 13500kms since it was fitted, with no ill effects as far as I know, but now after reading this I'm not really sure what to do! Will it store up problems for the future? I also don't know if the fuel pump was turned down for the emissions when it was first MOT'd and I suppose I'll find out when it goes for it's next one in May!?! Anyone else with views?

[chiefie]

i am a big believer in ' if it ain't broke, don't fix it '.
if your car is set up correctly you should have no problems with running / power or smoke. therefore if egr is working as it should and fuel pump is set correctly you should have no problems.

chances are that very few pumps, especially on 4m40's, have not been tinkered with and will still have the anti-tamper covers on the adjusters.
haven't read all the post on pocuk but got the jist of it. some of which i agree, and some i don't, but there you go!! each to there own.

some may have seen my advice on a tweak i carried out on my pump, this was found accidently as i had the pump in bits to repair a leak, when i put it back together i had a job setting it up, until i adjusted the pump to the position it is in now, giving good power and very little smoke

haven't blanked off my egr and as i said above, very little smoke, non of which is black.an engine in good order and well set up will not cause any problems with power or smoke or cylinder heads etc...

just my two penneth,

rik
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delicarik@hotmail.co.uk

[Rusty]

This is exactly why I thought it useful to post it here. In my case the engine was smoking quite badly and the plate certainly made a big difference. But like I said, now I have read how to clean and repair the EGR, I think it may be worth doing. In the meantime, I'm happy to leave the plate in, as I don't cane the engine anyway... (Much )
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[chiefie]

apart from going through deep water

rik
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delicarik@hotmail.co.uk

[Rusty]

Who me
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[Ginja Nutz]

Last time I looked at my blanking plate it had started to corrode through, so it may well be time for another inspection anyway.......

Good thing about an L400 - It only takes minutes to whip it in or whip it out
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Any information in this posting is correct to the best of my knowledge and I accept no resposibilty for any actions or results based upon it.©

[chiefie]

ooo errrr misses,

not like us 300 owners where the drivers seat removal makes it a little easier :?
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delicarik@hotmail.co.uk

[stevi]

Can't find old gasket any idea's where to get a new one, can't make my mind up to change back or not but better get gasket just in case.
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"Take it easy Take it easy Don't let the sound of your A/T wheels drive you crazy"

[mdocuk]

[rikyuu]

I've read similar things on a few websites regarding the EGR valve, that it reduces the amount of Nox emissions at high engine speeds which increase due to the higher combustion temperatures. At high engine speeds, the valve opens and allows the inert gases from the exhaust into the cylinders to cool the combustion temperature and reduce that particular emission.

I suppose the knock on effect of removing the valve is that the combustion temperature increases at high engine speeds.

I've blanked mine off and noticed no difference in performance, consumption or black smoke. Unfotunately I stripped one of the manifold threads in doing so and had to bodge it, so I can't put the EGR back on now.

Have a seach on the web regarding EGRs, most site seem to say the above. Also, all modern diesels seem to be fitted with EGRs.

eg see http://www.misterfixit.com/egrvalve.htm

[Boozy nights]

Some good posts here. When I first bought my Deli I read about this plate and noticed the beast was throwing out some crap from the exhaust, so I bought one, attempted to fit it and well lost it in the engine somewhere - whoops. Anyway i've bought another but not yet fitted it and I don't think I will. You have to ask yourself "how much smoke am I belching out?" okay first thing in the Morning (but not all mornings) there is a fair amount, but no more than a normal diesel car thats 13 years old, when I floor it pulling away there is some smoke, but again not that much. The idling sometimes is a bit lumpy, but again the car is 13 years old! Like many of you on here are saying "if it aint broke don't fix it", plus all the talk about emissions makes you paranoid!!

Just my view
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[robram552]

What I don't understand regarding the EGR is that it is meant to reduce combustion temperature, but surely the exhaust gases are hot (ever touched an exhaust manifold with motor running or just switched off??!!), whereas normal intake air is cool(er), some hot exhaust gases are entering the intake manifold how can an open EGR reduce the combustion temperature??
Since blanking off my EGR, I don't notice any change in performance, perhaps slightly better mpg, no pinging, only lots less black smoke under acceleration.
So mine's staying blanked off for the time being at least!!
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Delica 2.8 Space Gear Exceed
Audi A4 Avant Quattro 2.5TDi

[PinkPig]

[petemillis]

Robram, yes, the exhaust gases are hot, but nowhere near as high as the temepratures in the cylinders. What the EGR does is to recirculate some of the exhaust gases when the engine is NOT under heavy load (the primitive EGR system on our Delicas can't recirc when under load). What this recirculation does is introduce what is effectively an inert gas into the cylinders therefore reducing the combustion temps.

This reduction of combustion temperatures when not under load will allow quicker cooling of the cylinder head after the engine has been under load. The reason this could potentially be important is that the Jap spec Pajeros are set up with higher fuelling (which is why most smoke and the fuel pumps have to be turned back to get through the SVA test and MOT). Higher fuelling produces much higher combustion temperatures. But the recirculation of exhaust gases allows the cylinder head to cool down quicker when off load.

Now what happens if you turn the fuel pump up again after the SVA and MOT, and then subsequently blank off the EGR? You increase the combustion temperatures by increasing the fuelling, and then you remove the cooling effect of the EGR. So your cylinder head temperature will be increased. What we need to know is whether this increase in cylinder head temperature would put the temperatures higher than specified by the manufacturer.

Right, so now you might ask: "What about UK spec vehicles that don't have the EGR?". Well, these also run lower fuelling to meet UK emissions requirements, and as such the combustion temperatures will be lower anyway.

And you may also ask: "But if my cooling system is up to scratch then surely if will keep the temperatures low enough, won't it?". Well, it will keep the overall engine temperature within spec, but what causes problems in cyclinder heads is the temperature difference between each part of the head, and the temperature difference between head and block. So, by increasing the combustion temperatures you are increasing the difference in temperature between the internal surface of the cyclinder head where combustion occurs, and the other parts of the head where cooling occurs. It's differences in degree and variation in expansion that cause things to warp or crack.

Basically, my take on this is that if the fuelling has been reduced to meet UK emissions requirements, and then the EGR is blanked, there should be no increased risk of damage to the cylinder head. But if the EGR is blanked AND the fuelling increased in the pursuit of extra performance, or if the EGR is blanked and the fuelling kept the same as when it arrived in the country (i.e. it was turned down for MOT purposes then the importer cranked it up again) then there is a risk of damage to the cylinder head, as you ARE INCREASING combustion temperatures. This risk of damage would be the same if someone were to increase fuelling on a UK spec Shogun with the same engine.

A further question could be "What is the benefit of blanking the EGR?". Perhaps the following will help you answer that for yourself. When the engine is put under load the EGR valve closes so there is no effect on performance with a properly working EGR system. The only time problems occur is if the EGR is stuck open due to excessive build up of deposits in it. This is easily rectified by removing and cleaning the EGR. Some people leave it to soak overnight in cleaner, but all you really need is 10 minutes, a toothbrush and some petrol or parafin. If the EGR is totally fooked (i.e. the return spring or the vac membrane are damaged so it doesn't work) then blanking it off is cheaper than replacing it.

So you have a couple of choices. You can keep the EGR and run slightly higher fuelling (i.e. as it would have been in Japan) to improve performance, or blank the EGR and reduce the fuelling.
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Pete
1995 Delica Space Gear Exceed (PE8W) in LaGuardia silver with chrome tints and BIG round things.

[Ginja Nutz]

My brain still aches a bit but with the logic behind both the design, people's statements, the other quoted sources and the physics, it all seems straightforward.
Looking around at the other sources, I have to agree that EGR technology has come on since our rather agricultural system (now upto 15yrs old if you look at the L300s)

I've found my original EGR gasket, so I've decided I'm gonna remove my blanking plate at the weekend and go back to the EGR valve.

I'm the first owner of this car since coming into the country and I blanked the EGR off shortly after I got it, so my car has only ever been through the MOT blanked (since the SVA - but the fuelling may have been re-adjusted after this by the dealer).

Going on the emission figures that Pete posted after his MOT. I don't think there will be a problem. But the MOT isn't until December, so I'll just have to wait and see......
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Any information in this posting is correct to the best of my knowledge and I accept no resposibilty for any actions or results based upon it.©

[rikyuu]

Well I've re-fitted the old EGR and removed the blanking plate (had to bodge it on with 2 part super steel mix, but seems okay), so I can do some investigation and extend this debate endlessly!! :D

It seems to have some intelligence (Jim ) as it's operated by a vacuum pipe through an electrical solenoid.

Sticking my thumb on the open end of the vacuum pipe, there was no suction when the engine was cold, only when it got up to operating temp. So I guess the black smoke syndrome is caused by faulty EGR's as they shouldn't be open at all when the engine is cold....well, I say that, that's assuming mines working correctly!!

If I slowly pick up the revs, it appears to stop sucking at about 2000rpm, so this ties in with the thought that it may in fact operate at a low speed.

Of course, reving the engine statically is completely different to on the move as there is no load and hence you don't need much throttle to rev it, which ordinarily would mean there isn't so much vacuum in the inlet manifold.

However, I checked where the vacuum pipe come from, it goes into a rail that also feeds the brake vacuum, across the front of the engine to what appears to be a pump next to the PAS pump. Could this mean that it's not manifold pressure driven, but driven by a mechanical pump?

I guess that with turbo charged engines, there isn't a vaccum in the inlet manifold as it is pressurised by the turbo. And I've heard of secondary air pumps/vaccum pumps being fitted.

So...where am I going with this?

I also read 'ere;

http://www.autozine.org/technical_school/engine/petrol2.htm#EGR

that EGRs operate at low speed to reduce fuel consumption as well as emissions (and power output).

Well, as I still can't decide whether they're a good thing or bad thing, I tried mine connected and disconnect.

Connected it completely lacked power at low revs. The power seemed to kick in as the turbo spun up, but then vanished a second later.
This is probably exasperated by the fact that I've adjusted by gear box to keep the revs low.

With it disconnected it was much better, much more constat low down torque- so that's how I've left it. 8)

[chiefie]

[Rusty]

I would like to thank PeteMillis for taking the time and trouble to write out that explanation 8)

Based on this debate I think and I believe a few others agree, that it is best to see if you can get the EGR to work correctly by giving it a good clean and only if that fails is it a good idea to fit the plate as a cheaper alternative to a new EGR from the main dealers

Good job I cleaned all that mud off the engine then! Looks like I'll be spannering at the weekend
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