EGR Valves

[Tandum]

Modern engines feed exhaust gas though an EGR valve back to the Intake Manifold via an air cooler. That soot mixed with crankcase breather oils forms a sort of concrete though the whole intake system. Anyone with a modern diesel knows all about this.

Has anyone just blanked off the ERG inlet pipe from the exhaust to the ERG valve. How would or does this this generate an engine alarm.

[RyanJones]

Hi Robin,

The concrete you are talking about is one of many byproducts in modern systems that seem great in theory but sadly in the long term don’t work.

As far a blocking it off, it’s all going to depend on the car. Basically the air that is going into the engine is measured by an air mass meter. When the EGR is open the computer is expecting a proportionally reduced flow of air through the air mass meter ( as some is now being supplied by the EGR ). By blocking it off the flow through the air mass meter doesn’t change . Generally the computer will repot this as either a air mass meter fault or insufficient EGR flow. This is where the car is going to depend for the consequences. Some simply throw an engine light and let you get on your merry way. Others ( most modern stuff ) will shut down the turbo charger or introduce some other form of power reduction to protect the engine because there is a fault. In reality it’s because it’s an environmental issue.

Hope this helps

Ryan

[Tandum]

Only 10 bucks delivered from Poland for a blank.
But me thinks getting the egr valve range set to zero is the best option, it'll never open and the rest of the math calculates itself,

Should work for any car

[Tandum]

I just bought an old BMW x3 2.0 Diesel
Ergo the interest,

[RyanJones]

Ok. So how old is going to be the question there. If you have a DPF in your exhaust system then it may cause problems with self regeneration. BMWs use the EGR to increase combustion temperature to carry out the regeneration cycle so it may not work. As far as “ setting “ the EGR range to zero I’m not sure how you’d go about that without being able to change the software. In the normal diagnostic software the EGR range is set by upper and lower limits being reached. If the EGR reaches a limit too soon ie when the valve is blocked or jammed then it reports it as a fault.

[glend]

Robin, yes I have shut off EGR on my 2007 Jeep Cherokee CRD, (which runs a 2.8L VM Motori engine). I did this back in 2009, and it has run perfectly ever since. I want to point out that in my opinion, this significantly prolongs the life of a diesel engine, and you only have to look at the oil to appreciate how clean it keeps the internal surfaces and thus wear reduction caused by combustion product ingestion.
Blanking off the EGR can cause a number of problems, but there are ways to disable EGR operation without a blanking device; software changes are probably the best. Software changes that delete EGR operation are available, and while technically not legal, there are no emission system inspections in Australia, and therefore likely no one will ever know.
The reason I do not recommend simply blanking off EGR ( which is usually done at the exhaust manifold), is that some manufacturer software uses the same pipe pathway to dump turbo over boost into the exhaust manifold (this is a very effective technique to extend the life of variable vane turbos and negates the need for pop off valves in the turbo intake). The software simply opens the EGR in over boost throttle lift off situations and thus diverts over boost into the exhaust system. If you block off EGR then that over boost cannot be dumped and you have a situation where over time the turbo can be damaged, and turbos are expensive to replace.

Finally, shuting off EGR on old diesels is usually a waste of time, money, effort etc, simply because the damage that will have already been done to internal bearings, rings, etc has already been significant.
If the vehicle is fairly young, and you intend keeping it for a long time, then yes there are life span extension benefits. The exception might be for vehicles under going a full rebuild, with replacement of old internals with new parts, sadly most Euro diesel designs cannot be rebuilt anymore (Mercedes are terrible in this regard).
So that is my 2 cents worth.

[The_bluester]

Plenty of people do it

Caveat #1, blanking the EGR is unquestionably illegal.
Caveat #2, most modern engines will throw a code if you simply blank it off. I am not really sure how they monitor it, I think what Ryan wrote is probably right in that the ECU will be looking for a dip in MAF reading as the valve opens. A lot of people pay for a tune and get the EGR disabled in software.

EGR should not impact DPF regeneration, it is actually used to reduce combustion temperatures, not increase them. The drop in combustion temperature reduces output of oxides of nitrogen, something that diesels are generally fairly nasty at. The high compression ratio lends itself to conditions that produce those emissions.

DPF regens are done by injecting additional fuel, either using the normal injectors after the normal combustion part of the cycle or some have an additional injector in the exhaust system which injects fuel directly to the exhaust. The goal being to ramp exhaust temperatures up high enough to burn the accumulated soot out of the DPF (Somewhere in the region of 700 degrees Celsius) I can certainly see the advantage to the supplementary injector, it means not subjecting the exhaust manifold and turbo and some sensors to the heat of a regen. Regens are pretty hot, if you have ever gotten out of a modern oiler and it smells like someone has been cutting steel with an angle grinder, that is probably a regen in action. I had one take the hair off my shin as I walked behind the car once.

Glen, I am not sure about EGR being a bypass path for boost on a diesel. Firstly, the only time I know of that the engines I am aware of close the throttle body is on shutdown (To make them stop more smoothly instead of the thud that the high compression ratio can cause) and actually during EGR operation to create a larger pressure difference and draw more exhaust in, given that diesels run without throttling. The other advantage is it can help stop a runway engine, google vids for runaway deisel if you want to see scary stuff. I am not at all sure they would provide much blowoff valve action as it is often the case that the exhaust manifold pressure on a turbo engine is almost the same as the inlet manifold pressure.

[Wilso]

What about installing an oil catch can, they separate the oil out of the vapours before it enters the inlet manifold. Common in the 4WD community.

[Tandum]

Cheers Glen. It's an old and busted BMW, which what I normally buy. 2008 E83 164k Klm and my BMW specific ODB reader tells me glow plug 1 is stuffed and the DPF is at a mileage where it needs replacing. I've read that DPF fault can be cleared using the appropriate software which I'm trying to find. A catch can may be the quick solution. The breather pipe is very easy to get to.

I thought the EGR got tacked onto diesels to lower the temp in the combustion chamber which in turn creates larger exhaust particles which then require the DPF to clean them up. Unfortunately they never released this model X drive in the US as a diesel so I'm forced to gleen most info on the engine from British forums. And to make it worse no one makes an aftermarket manual which covers the diesel X drives.

[RyanJones]

On BMWs the DPF fault will not clear with glow plugs not functioning. Be careful replacing glow plugs in these engines. They are notorious for snapping or stripping threads. Also generic readers sometimes don’t differentiate between glow plug faults and glow plug activation faults which are the glow plug module. Once you have cleared the other faults you can clean the DPF and actually tell the DME that you have replaced it and you’ll get a fresh 160,000 life left.

[glend]

Closing the throttle body plate, is typically a device used to prevent diesel runaway, and completely separate to most EGR valve setups, although the throttle body plate can be used to generate suction into the manifold for EGR gases when the valve itself is opened. The throttle body plate in a diesel, is not a throttle per re as in a petrol car, it is a runaway safety device primarily.

What I was referring to was typical intake over pressure situations, where say during hard acceleration you suddenly have to back off the throttle suddenly. This results in the turbo vanes closing to idle position and the high pressure in the intake pushes back against the vanes, seerking a way out by a the only available path. This sudden reversal has been known to damage the variable vane mechanism and leads to reduced life span of the turbo. Throttle body plate plays no role in this action as it is only used in shutdown to prevent runaway or for EGR suction changes, it does not prevent blow back in the intake.
As far as your claim that exhaust and intake manifold pressures are the same, this is incorrect in the situation I described. The intake is already pressurised when back off occurs, at that point pressure flow at the intake valve face reduces significantly, by nature of less duration of being opened (high rpm suddenly reduced to idle), which means pressure cannot equalise, hence the blowback through the turbo, seeking equilibrium.
The ECM is constantly monitoring the throttle pedal position sensor, when it sees a sudden back off, when the rpm has been above its set trigger point, the ECM commands the EGR valve to open momentarily to bleed off the over boost in the intake (thus protecting the turbo vanes). Because the intake pressure is higher than the exhaust pressure at that time, the over boost flows out the EGR valve to the exhaust manifold.
This has been the operational model of Chysler Jeep, and some GM turbo CRDs for a decade. Of course different manufacturers may take different approaches to this process.

[Tandum]

I've read the plugs often won't come out.
Might stick it into the local indy shop.
They'll have a lot more experience with them that I do.
And it is an activate fault but only plug 1 is listed.

[RyanJones]

Sounds like a good plan. Be prepared that something may go wrong though. I’d say I have trouble with maybe 1 in 5 BMWs but if they’re careful and patient it just takes extra time. I’ve only ever had to remove the cylinder head on one car because of it and that was a Peugeot not a BMW.

Just to clarify what I mean about activation fault rather than active fault. The actual code is glow plug activation cyl 1 rather than glow plug cyl 1 - active. The former is a glow plug module fault, the latter is a faulty glow plug if that makes sense.

[The_bluester]

I always assumed they would be used to help in case of a runwaway (And I know all three oilers I have had had one, and all three closed them on shutdown) but two Nissan manuals (Different cars) stated different purposes, one specified it was used to reduce compression thump on shutdown (An old D22 Navara with the ZD30 hand grenade and when I tried disconnecting the actuator, it really did stop with a car shaking thud) and the other (D40 STX-550 with the V6 TDI) states it is used to increase EGR volume, given it would have no manifold vacuum to help it along otherwise and in some conditions the inlet pressure might be higher than the exhaust, so flow would go the wrong way.

Regards the variable vanes, they are on the hot (Turbine) side anyway. Without whacking a camera in there it is hard to say how they behave on getting off the throttle, but unless the throttle body is snapped shut (And I understand it not to be, but I would need to try some OBD or CANBUS sniffing on the D40 to see if it's position is reported) it won't cause any any boost pressure spike anyway.

Funny enough on my race car I have always run without any form of blow off as they are a bit much of a blunt instrument for my liking and made the car harder to drive fast, on that car I just let the compressor stall and sound like a demented pigeon, and if it died, it died. The turbine housing cracked around the wastegate flap from the heat before the compressor gave any trouble. That might change with my new ECU, the maker of that is fond of using a small electronic throttle body as a blow off valve, controlled by the ECU. A scalpel instead of the traditional BOV meataxe.

[HarryD]

Try as I will, but I can't find any of these things installed in my Tesla!

[The_bluester]

Some of us could be so lucky.

We are just about to buy a new car and I reckon it will be our last fossil fuel only car. Electrics are not quite there yet for our usage but by the time we would be looking to trade again they probably will be.

[Bart]

To simplfy things, the EGR system on a vehicle circulates a small amount of exhaust gas back to the combustion process to reduce oxides of nitrogen in the outgoing exhaust stream.



Oxides of nitrogen are extremely harmful to any living thing and internal combustion engines are a major contributing factor to air pollution, making up for over 50% of the emission that contribute to smog and acid rain.


Do the right thing and have the vehicle fixed properly.

[Tandum]

http://starshed.net/What/Yuk.jpg

Look into it. Someone ****ed up.

[Bart]

That is a crankcase ventilation issue, not an EGR issue.

[RyanJones]

No it isn’t

[Tandum]

I got plates on my X3 today and it returned 5.4L\100Klms under cruise control down the freeway so it's no where near as chocked as I thought.

An oil catch can is in the mail, why aren't these standard?

And a Hitachi glowplug controller is coming from Lithuania.