EGR block side effects

[06PAJ]

Talking to bloke today refuses to block/plug-in delete egr due to excessive high temps this may cause in combistion chamber resulting in detonation.
Prefers to catch can reduce oil into inlet only

Anyone tested this.... not sure you scan tool will give combustion temp, only engine temp.

[littleriver]

Talking to bloke today refuses to block/plug-in delete egr due to excessive high temps this may cause in combistion chamber resulting in detonation.
Prefers to catch can reduce oil into inlet only

Anyone tested this.... not sure you scan tool will give combustion temp, only engine temp.

would one say engine temp will increase as combustion temp rises ?

...

[06PAJ]

Yes & no

[MatthewP]

Talking to bloke today refuses to block/plug-in delete egr due to excessive high temps this may cause in combistion chamber resulting in detonation.
Prefers to catch can reduce oil into inlet only

Anyone tested this.... not sure you scan tool will give combustion temp, only engine temp.

The guy is misinformed.

Diesels run better without the egr.

They are only there for anti pollution reasons.

Egr isnt active when at full throttle, which is when excessive temps are a concern.

There are plenty of other threads where people have gone into more explanation about how it all works.

Matt

Edit.
Diesels dont 'detonate' in the 'pre ignition' sense of the word.
The diesel ignites as it is injected into the combustion chamber.

[06PAJ]

Does combustion chamber need to increase 100degrees to see a 4 degree change in engine temp ?

[NTBenny]

Something worth reading.

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

I haven't heard of anyone's engine failing due to excessive combustion temps after blocking the EGR. Also combustion temps would be reflected in the exhaust gas temps of which I've never heard of excessive temps being seen after the EGR is blocked. In my opinion the benefits far out way the negatives when blocking the EGR.

Benny.

[Pickles77]

Adding a catch can without deleting EGR can do more harm than no catch can with EGR.
If a catch can is taking all of the oil vapor out, the EGR will be returning harsh particles formed during combustion into the cylinders. This is what is normally caught by the oil vapour (forming the black gunk), a catch can with the EGR active will be like slowly sand blasting the engine.

EGR literally harms the performance of the engine in efficiency and therefore power.
Less 02 in the combustion, which yes produces less heat, which means less N0x gases, at the cost of incompletely burnt fuel.
Deleting the re-circulation will theoretically increase combustion temps, but the effect of removing the exhaust gas temp and repalcing it 100% fresh air almost eliminates this. Realistically there will be no noticeable change. There are cases where the EGR improves fuel economy and such, however on a mechanical engine like the 4m40 the control is not accurate enough to portray this (in my belief).

The worst case scenario is that he actually has increased combustion temps, in which the fuel will need to be cut back slightly, or more boost introduced (what a shame).

[Dicko1]

Adding a catch can without deleting EGR can do more harm than no catch can with EGR.
If a catch can is taking all of the oil vapor out, the EGR will be returning harsh particles formed during combustion into the cylinders. This is what is normally caught by the oil vapour (forming the black gunk), a catch can with the EGR active will be like slowly sand blasting the engine.

EGR literally harms the performance of the engine in efficiency and therefore power.
Less 02 in the combustion, which yes produces less heat, which means less N0x gases, at the cost of incompletely burnt fuel.
Deleting the re-circulation will theoretically increase combustion temps, but the effect of removing the exhaust gas temp and repalcing it 100% fresh air almost eliminates this. Realistically there will be no noticeable change. There are cases where the EGR improves fuel economy and such, however on a mechanical engine like the 4m40 the control is not accurate enough to portray this (in my belief).

The worst case scenario is that he actually has increased combustion temps, in which the fuel will need to be cut back slightly, or more boost introduced (what a shame).

Good explanation....

[Hill]

06PAJ

Perhaps the simplest explanation is that diesel engines ran perfectly well before EGR's were added.

They will run marginally hotter and fuel economy improves by around 3% when deleted.

Hill

[Apollo]

06PAJ

...

They will run marginally hotter and fuel economy improves by around 3% when deleted.

Hill

That has been my experience.

[Kumabear]

Personally on my car it does have its negative.

Car drives overall nicer since she is all clean in the intake.

Cruising fuel economy is great and improved since I turned the EGR off

Now the negative side effect
In Stop start traffic (lets face it not a strong point of a big heavy 4x4) the EGR being blocked has had a pretty bad impact on my fuel economy.

Below is my understanding of the issue I could be totally wrong who knows haha

EGR does serve a purpose other than purely emissions, because it is letting the engine breath a mix of normal air and oxygen depleted air (egr gasses have already been through combustion once) it effectively reduces the engine displacement when its active.

Think about it, per combustion cycle under no boost the engine must suck in X amount of air then it needs to inject Y amount of fuel in order to get a correct air to fuel mix.

If you are pushing a 50% mix of oxygen depleted air which is what EGR is (plus nasty soot) and 50% normal fresh air then you effectively halve the displacement of the engine meaning you can then inject half of the normal amount of fuel and still hit the same air to fuel ratio. This reduces fuel use and also reduces emissions its actually rather clever tbh and I think it works quite well on petrol cars which have far less soot in the exhaust. ^ this assumes that 100% of the oxygen in the exhaust gasses is depleted which is probably not the case but lets not split hairs and make the math hard okay

In short its still worth it to not have a clogged engine and any extra fuel use in traffic will be more than offset in savings in the workshop from having to have the manifold cleaned out as well as a little better economy cruising and a touch more responsiveness.

[Scott84]

I am still reading up on the EGR delete issue, and while it seems like the verdict is almost unanimous on the forum that it is a safe and even necessary mod to do, I am hesitant to alter anything which significantly changes the way the manufacturer intended the engine (or other vital components) to operate for fear of unforeseen issues it may cause.

My understanding is that the SPV module electronically blocks the EGR valve by sending a false low temperature reading to the computer controlling the engine/EGR? My question is around what the side effects of this may be, has anyone considered that potentially temperature readings by the CPU may alter the fuel map used, i.e. the CPU may change the air/fuel mix for colder temps? When the air temps are lower air is more dense, if the CPU is assuming that air is more dense than it is this could potentially impact the air/fuel mix? Perhaps in colder temps the CPU runs the engine leaner to increase the operating temperature, in hot weather this could potentially cause damage to the engine?

Has anyone considered these potential side effects and what they might do in terms of reducing engine longevity? And also, does anyone know why are these issues seemingly far less of a concern for other diesel owners with EGR (i.e. Toyota D4D), it seems to be far less commonly a discussion point on those forums?

[dbdb]

Options:

• Do an EGR mod (resistor fix is the simplest) and reduce the amount of soot that will ultimately block the inlet manifold. I've not read any evidence that it causes any engine problems.

• Do a catch can mod (with or without EGR mod) - eliminating the oil to mix with the soot in the exhaust reduces the build up in the inlet manifold. Again, not read anything that it causes any issues

• Don't do the mod. Have performance degrade over time and eventually pay someone/do it yourself to clean the inlet manifold. Seems pretty clear that if not actually harming the engine, its definitely harming its operation and performance and if not fixed will result in it not working.

As for other vehicles, I believe that soot blocked inlet manifolds is an issue to some extent for most diesels with an EGR. Some may have better designed manifolds that handle it (soot) better.

EGR is a fix for a single element of vehicle pollution (NOX) in certain conditions. The fix is at the expense of vehicle performance and reliability and probably fuel efficiency.

[erad]

Some of the talk above refers to getting the correct air/fuel ratio. With a diesel, there is no such thing. A diesel takes in a gutful if air every stroke, and injects enough fuel to deliver the power asked at the time. Thus you could have am airfuel ratio of over 200:1 at idle, when no useful power is being generated. Diesels handle this variation quite well, unlike petrol engines which must have a specific air/fuel ration (around 14:1 or so) or combustion will not occur.

Turbos confuse things a bit more because depending on how hard you are pedalling, the amount of air being pumped into the engine will vary. With no boost, it would be 1.6Litres of air everyrevolution. When you have full boost, it is more than double this volume being pushed into the engine because you have more than twice the standard atmosphereic pressure being pumped in. Luckily we have a fairly smart computer which takes in the airflow meter readings of temperature and airflow rate, and then it calculates the actual amount of air being drawn into the engine. It then decides how long to open the injectors and what specific opening sequence to use for that stroke. Luckily I don't have to thonk about that because I simply couldn't.

Regarding EGR, it may possibly have some benefit in keeping the exhaust airflow temperatures up a bit higher than they would otherwise be. This could help with spooling the turbo up, thereby reducing teh turbo lag. I know that with the foot flat to the floor and low revs, my engine is as dead as a dodo. It takes a significant time to spool up the turbo and get things moving. (This is where an auto transmission comes into its own because it will try to keep the engine revs up).

Having no EGR is, I think, still a major plus. You will still get soot coming in from the sump gasses being picked up and fed into the air intake, but the volume of soot will be miniscule compared to the factory setup which is designed to limit NOX emissions at higer temperatures. The sump gasses contail oil vapours, and these can be 95% absorbed with a catch can.

EGR would, I imagine, improve the warming up of the engine. I live in a cold climate, and even without EGR block, the engine can take over 20 km before my scangauge shows 85 Deg C Cooling water. It has always been thus. If I had an EGR block it would probably take even longer to warm up because warmed air is not being recirculated through the engine.

As for economy, theoreticaly an improvement could be made because you get a gutful of fresh air every stroke with and EGR block, but this would apply only if you were using full throttle as well. Personally, I rarely have full throttle anywhere, so an EGR block would probably not make much difference to my economy.

[old Jack]

EGR operation does not warm the engine up quicker as it remains closed at temperatures below 9C, and this is what a resistor mod does. It gives the EGR control in the Engine ECU a signal that says the #1 inlet air temp (measured at the airbox) is 9C or lower. The #1 air temperature sensor is only used to control the EGR and no other function.

OJ.