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Discussion Starter · #1 ·
havn't seen anything here on EGR mods.

i've just plated my ZD30, the same way as the patrol guys do. just fit a plate on the inlet manifold side of the egr pipe. dispite only 50 tho on the clock it has quite a bit of build up in the inlet manifold :(.
so far its been a good improvement. no bogging on takeoff and blowing huge clouds of black smoke, much more responcive low down and hopefully a lower EGT. also a lot less engine rattle.
 
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Is this the same engine we get? the 174 brakeHP renault engine?

Do you have emissions tests like us? (yearly on all over 3yr old cars)?

oh - and welcome to the forum ;)
 

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Guy,
With Land Rover vehicles, the EGR (Exhaust Gas Recirculator) is fitted for the US market I believe. There emmision requirements are different to the UK. The EGR only works at tickover rpm.

In the UK, our MOT emmisions are done on diesels at high revs when the EGR is closed therefore it makes no difference to the test results if its working or blanked.

Not sure about the Nissan but guess its probably similar. In which case, I'm going to consider blanking mine off too to avoid filling the inlet with soot.
 

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Discussion Starter · #5 ·
thats on the 110kw ZD30 non-intercooled, not surewhat that is in HP.

fortunatly we have no emmisions testing just yet (we will soon no doubt). however we do have a requirement that vechiles cannot produce smoke and seeing as EGR contributes to soot creation..... ;) we are well used to 2nd hand jap imports which often have faulty EGR systems, the cheap fix is to block them off. jap deisels have had EGR systems for the last 15+ years.

all the newish 2.5 and 3 litre nissian turbo deisels all have EGR.

the EGR works at low throttle but i think it tends to dump way to much egr in to quickly hence how bogging off the line problem. also its seems to be a contributing factor in all the ZD30 engine failures.
 

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The main factor with the ZD30DDTI's blowing up is over boosting. The multi vane turbo in the patrol's, is the turbo isn't controlled properly by the ECM and ends up over boosting and melts no 2 cylinder.

Mine D22 has 25 000km's, I wanna block the EGR valve but I have alot of warrenty left to go.
 

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Discussion Starter · #7 ·
the patrol is a bit different due to their variable turbo. with the patrols the EGR valve sticking can also cause the turbo to overboost as well as the more comman MAF sensor failure.

the navaras blowning up is not caused by overboosting. more to do with oil problems which i think are increased by the soot made from the EGR and problems caused by the clogged up inlet manifold.

the good thing about blocking the EGR valve is if the motor dos die you can simply take the blocking plate out very easly.
 

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its a bit long but here goes:

The EGR valve recirculates exhaust into the intake stream. Exhaust gases have already combusted, so they do not burn again when they are recirculated. These gases displace some of the normal intake charge. This chemically slows and cools the combustion process by several hundred degrees, thus reducing NOx formation.

The EGR system must precisely control the flow of recirculated exhaust. Too much flow will retard engine performance and cause a hesitation on acceleration. Too little flow will increase NOx and cause engine ping. A well-designed system will actually increase engine performance and economy. Why? As the combustion chamber temperature is reduced, engine detonation potential is also reduced. This factor enabled the software engineers to write a more aggressive timing advance curve into the spark timing program. If the EGR valve is not flowing, onboard diagnostics (OBD) systems will set a code and the power control module (PCM) will use a backup timing curve that has less advance to prevent engine ping. Less timing advance means less performance and economy.

Most importantly the increase in the cylinder temprature can cause other problems like the old petrol engine faults caused when running to lean.

The Landrover 300tdi as fitted to all the military defender variants has an EGR fitted to it and when it fails it causes pinking, its a simple system so doesnt retard the timing. Noticable fault finding for us simple mechanics. But with advance engine tuning as in the D40 and the OBD system, which in turn waits for the EGR signal(one of 8 ) I cant see it being that good too remove it. A slight increase in the short term doesnt seem to offset the possible long term detrement to the engine. and as dunc said they dont pass the Emissions test we have in the uk with it non operational.

Hope that helps a bit, I not experienced with your engine but if its similar to most its not just fitted for the tree hugging liberals, its fitted for a good reason. I would look at making the engine flow a bit better first.
 

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Discussion Starter · #9 ·
sorry daletur328 i don't agree with a lot of your post. your egr explanation is fine for a petrol but not a diesel.

and cause engine ping......engine detonation potential
that all sounds like its referring to petrol engine.
aggressive timing advance curve into the spark timing program.
now thats definitely for a petrol engine! !

in a diesel ANY egr retards performance, there is certainly none that increase performance or economy. ever test and lab testing published on the net that i have seen so far has found that. so does everyone who has disabled an egr system.

the BIG problem with egr on a diesel is it increases soot and it increases it exponentially.
 

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sorry mate my mistake, i`ll learn to read after i wrote it!!!!!!!! :? but on the diesels Pinging still occurs when the timing is out, (admitedly diesel knock is a more prominant fault with that people are aware of with diesels). And the part about timing should read FUEL INJECTION.
my muck up :roll:
But the improvement on modern diesel engine is a fact, older engines and EGR sytems used to be true about killing power, but not so on the newer versions OBD1+OBD11( it shows as a fault and alters mapping) but link is a bit better than I at explaining it, as i said dont know the engine but persume its fairly modern.

http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

as i mentioned IMHO is unnessasary risk to engine life, but each to their own. I dont have to pay for repair and have to pass emission tests. but any comments fair.
 

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also found a link from an australian magazine about your engine @
http://www.4wdworld.com.au/releases/navara.htm.
this is a very informative blog on your engine. and mentions in details the role of the EGR in your system. 8)

if this is a common review with your mags then good on them, wish our vehicle reviews had this much detail, other than, seats comfy and engine noisy at speed. :x
 

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Discussion Starter · #12 ·
i know they change the injection timing to try to recover some of the lost power in some motors.

my theory- they have little means in which to tell that the EGR is working correctly so they can't run it to advanced without risking problems in normal running. from what i read some time ago some system can tell the EGR works by the throttle input increaseing when egr is opened. however it has to be at constant cruise at certain rpm, temp etc.
EGR sytems are so unreliable and with minimal feedback they can't push the motor to hard otherwise it would simply fail every time the egr failed which is fairly comman.
blocking it off saves a lot of hasle and cost later on.
 

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As i said not sure what system you have but if you look at the EGR and it has an electronic connection with three wires it tends to be self sensoring, batt voltage/earth and variable. i know a lot of sytems have an electrical plug and a vacuum tube connected. when the ecu gets all the right signals a simple valve opens, allowing the vacum tube to activate the EGR diaphram allowing it to operate and that the electrical socket simply notifies the ecu the valve is open. some can tell with the degree but most it is a simple open/closed signal. having looked on various sites about it the subject most are unspecific with reference to diesels. some think good others think bad. but in the whole it seems to be a good thing on older systems but some of the newer OBDII systems it does have a bad side effect.
with landies the ecu does get a sensor feed. a common way of disabling the 300tdi EEGR valve is by putting a ball bearing in the tube or just pull the pipe off and simply put back on for MOT. but after rallying rovers (every bit of BHP helps) it make no difference to lap times, and the rovers engine normally blows up too soon to find out the long term repocussions.
but IMHO if it was for the D40 not a chance, not in warranty anyway, but if your egr fails often and your out of warranty just keep an eye on it. and if you know a mechanic with diagnostic kit ask him to check the fault codes. If it registers one, falsify a reading and see what happens to the mapping.

dale
 

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Discussion Starter · #14 ·
the old toyotas i'm used to have the old vaccum diaphram system.

the ZD30 has elecrial mulitable wires so i'm assuming it has feedback on valve position.

with common rail injection they have the ability to shape the fuel and also adjust the timing greatly. so its a bit of a concern about what they do to regain lost power while EGR is on. on the other hand because EGR is only on low throttle and low power situtuions the motor should be able to handle any timing advanceement even if the EGR is off. als the cooler air going in instead of the hot EGR also helps in that respect.

its a bit of a curly problem as EGR causes so many problems and is well known to be problematic expecially if the motor is making large amounts of soot due to the EGR.
 

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I know this is an old post but found some important info on the egr. Some people might experience driveability problems when they block the egr but it might be related to the throttle chamber.
look at this drawings. this will help to understand our egr system.

it shows clearly that we also need to modify the throttle chamber to keep it open since we are not using the egr anymore.
Maybe removing the plate from the butterfly might do the trick or cheating the solenoids.
this next diagram shows when they are open or closed.

post your ideas
 

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Discussion Starter · #16 ·
that drawing shows the typical older low EGR systems comman for 90's vechiles. the current navarra ones are electronic variable ones, finner control for the large amount of EGR they use.

yes disabling the butterfly is generally a good idea. it generally only closes at idle (ie coasting downhill) to increases EGR, which when coasting downhill is not a bad idea at all. all other times it is open.
however the butterfly does seem to close partly dueing gear changes, no doubt due to taking foot off throttle. so disabling it makes gear changes a lot better.
 

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everything i've heard about blocking the egr is bad! Namely overheating due to the increased combustion temperature that results from stopping the mixing of exhaust gas (which lowers this combustion temp). Plus the guys who I know have done it to patrols have done it to older models ( I'm assuming don't have sensors to regulate valve position).

Aside from all this, no offence mate, it seems to be an "old school" type of mod. Like knocking the baffles out of your exhaust with a srewdriver! and a mechanicalk approach to an electrical situation (with respect to injection timing and so forth).
 

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Discussion Starter · #18 ·
MooseNav said:
everything i've heard about blocking the egr is bad! Namely overheating due to the increased combustion temperature that results from stopping the mixing of exhaust gas (which lowers this combustion temp). Plus the guys who I know have done it to patrols have done it to older models ( I'm assuming don't have sensors to regulate valve position).

Aside from all this, no offence mate, it seems to be an "old school" type of mod. Like knocking the baffles out of your exhaust with a srewdriver! and a mechanicalk approach to an electrical situation (with respect to injection timing and so forth).
would love to know where you heard all this.

everything i've heard about blocking the egr is bad! Namely overheating due to the increased combustion temperature
actually its the other way around. ie blocking EGR LOWERS motor temp.

EGR lowers flame temp BUT it actually increases EGT (exhaust gas temp). this is mainly due to the increase in inlet temp (even with cooled EGR). the motors can handle the higher flame temp without a problem but they can have problems with high EGT's. eg an EGR valve stuck open can cause high enough EGT's to cause piston damage. EGT damage is cumulative and you won't know it till the piston lets go.

one of the reason the patrol (the ZD30 powered) block the EGR is to lower the EGT's as they have been having a lot of piston failure due to high EGT's.

the idea behind EGR is not new, the same old faults are still there. old school tricks still work well.

one of the most common faults is sooting up the intakes. intake restriction causes loss of power and fuel economy and also increases EGT's.
catch with new motors is the more EGR you use the more soot you make which then fouls up the oil and intakes which makes more problems. it also clogs cat converters and really needs soot filters so stop it polluting the air.
 

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Heard it from a couple of fuel injection blokes. Got onto the subject while we were talking about retuning after I fitted an intercooler and chips etc.

I may have the wrong end of the stick, but to my understanding, introducing exhaust gas into the mix is done as exhaust gas has a higher specific heat, therefore lowering the peak combustion temperature. Offset of this however is that A) you increase the temp of the intake (due to hot exhaust gas) and hence the amoun t of oxygen in the mix, and B) Reducing the specific heat ratio means that you gain less power from the stroke (as you're saying).

The problem I see with blocking the egr is that, yes you may lower the intake temp and therefore increase the oxygen in the mix but this in turn (due to more oxygen) will increase the combustion temperature, then you add the effect of the lack of egr (lowering the specific heat capacity) and you have double edge sword contributing to higher engine temp.

Furthermore I don't understand how you can lower the combustion temp and inrease the exhaust temp as a result? (you may need to explain this to me a bit further) and equally vice-versa (if you increase the combustion themp by blocking the egr, how can this in turn lower your exhaust temp?) Seems a bit illogical to me
 

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Discussion Starter · #20 ·
introducing exhaust gas into the mix is done because exhaust gas is inert (its already burnt so it can't be burnt again). this inert gas tends to 'snuff out' the flame during combustion resulting in lower PEAK combustion temps. the lower temp means nitrogen doesn't get burnt to form Nox (pollution).

yes you may lower the intake temp and therefore increase the oxygen in the mix but this in turn (due to more oxygen) will increase the combustion temperature.....and you have double edge sword contributing to higher engine temp
yes and no. disabling EGR increases PEAK temp but lowers the engine temp.

i didn't quote the bit about specific heat capacity as it makes it confusing and long winded ;).

you need to remember that intake air has a big cooling effect on the motor. the main source of heat in a diesel is from the fuel. how hot the motor runs depends on how well its cooled. roughly put the more air you shove in the cooler it runs as the air cools the motor.
when you replace that cool air with 400°C exhaust gas the motor will run hotter simply because you removed what was cooling it.

Furthermore I don't understand how you can lower the combustion temp and increase the exhaust temp as a result?
remember that regardless of EGR the overall amount of heat comes from burning the fuel. burn the same amount of fuel you will get the same heat regardless of EGR or peak temps.
an example... EGR off, inlet air temp is 30°C, add fuel and burn. exhaust temp is 600°C.
now with EGR on, inlet temp is 200°C, ad the same amount of fuel and burn, exhaust temp is 200°C + the heat from the fuel(600°C) + more due to lack of cooling from the intake, - a bit due to peak combustion temp is lower, so you get exhaust temp = 700°C.

basically the EGR drops the PEAK temp but increases the AVERAGE temp. its this average temp which overheats motors and melts pistons.

the higher non-egr peak temp is not a problem as the motors actually turn off EGR at full throttle anyway, which is where you also have the hottest engine temps due to maximum fuel.

turbo's throw a small curve ball into the mix. when you go full throttle off boost you have limited amount of air going into the motor but lots of fuel. this rich mix nad limited cooling means high exhaust temps. if you have EGR on and especially if the inlet manifold is sooted up restricting the air flow (which is needed to keep the exhaust temps down) then you can have dangerously high exhaust temps very easily.

if you run an EGT gauge you will probably notice the EGT's drop when you fitted the intercooler. decreasing the inlet temps decreases exhaust temps.
 
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