D4 VEA 'check engine' light / EGR fault thread

[Harvey1512]

No limp mode for me and the light has been on for three weeks now. Not a worry, just an inconvenience to go to the dealers to get it sorted.

[Gilesme]

Originally Posted by Rooster

I have seen a couple of these for there 18k services now with no issues and apart from the EGR issues ive not really seen any other problems with these VEA engines,

i suppose the higher mileage vehicles are perhaps less prone to the issue, as probably spend extended periods of time at higher speeds ?

would better quality fuel help ? it's one of the reasons i try to use power diesel whenever possible (apart from using BP equivalent at the moment, as for ever £50 i put it, AMEX gives me a fiver back !).

[craigv60]

Originally Posted by Gilesme

i suppose the higher mileage vehicles are perhaps less prone to the issue, as probably spend extended periods of time at higher speeds ?

Possibly so. If it is the case that cars used for more long journeys at speed are LESS likely to get EGR problems, that could imply the problem is caused by soot / deposit build up rather than an actual component failure.

[Arianne]

Originally Posted by craigv60

Possibly so. If it is the case that cars used for more long journeys at speed are LESS likely to get EGR problems, that could imply the problem is caused by soot / deposit build up rather than an actual component failure.

I make no claim to be a techno-piston-head. But I have just read this and thought I would post it here, apologies for the length but I think it's worth it for the forum members who are interested:

Because the EGR’s recycled exhaust gas displaces some of the air within the combustion chamber, the engine’s efficiency is reduced. For this reason, the EGR system doesn’t operate during times of heavy acceleration. It also doesn’t operate during idle, because the presence of exhaust gases at idle tends to cause uncontrollable rough running.

EGR systems operate primarily when the vehicle is cruising under light load. Because there is less demand on the engine when the vehicle is cruising under light load, the engine can afford to temporarily lose some capacity. Also, because of the cooling effect of the EGR system, the engine can run cooler when the vehicle is cruising under light load. Because the engine is cooler, the engine’s lubricating oil is cooler as well. Cool oil lasts longer and works better than oil that has been continuously overheated. Therefore, the EGR system is important for the cool running of the engine and also in the protection of the engine oil from continuous heat.

In the real world, EGR valves often don’t work very well.

What goes wrong is this: the exhaust gases from the vehicle’s engine contain much more than just carbon dioxide: they also contain dozens of chemical by-products, left behind after the fuel was burnt inside the engine. One of these by-products is a fine dust, known as particulates. This dust is mostly unburnt carbon fuel. The more efficiently the diesel engine burns its fuel, the less carbon dust is produced. However, no diesel engine works with anything like complete efficiency and, over time, the carbon dust inside the exhaust gases begins to clog up the EGR system, reducing the movement of the EGR valve. This clogged EGR valve causes the engine to run badly due to an imbalance in the fuel/air mixture. Because the engine is running badly, the fuel is not being consumed efficiently. Because the fuel is not being consumed efficiently, more carbon dust is produced. Some of this carbon dust within the exhaust gets recycled by the EGR system, clogging the EGR valve still further. The more the EGR gets clogged, the more carbon dust is produced. The more carbon dust is produced, the more the EGR valve clogs. This viscious circle continues until the EGR valve jams completely open or closed.

If the jammed EGR valve is not repaired or replaced quickly, all sorts of problems may occur.

Four of the most common are rough running, high fuel consumption, turbocharger failure and, sometimes, total engine failure. Here’s how it works:
When the engine is cruising, the EGR valve is supposed to open to allow the carbon dioxide in the exhaust to cool the combustion chamber. However, if the EGR valve jams open, exhaust fumes are being fed into the engine at all times. This can mean poor acceleration and rough running, because the excess exhaust fumes are depriving the engine of oxygen. Because there is insufficient oxygen, there’s too much fuel, so the unburnt fuel starts spewing out of the exhaust as black smoke, especially when the engine is at idle. Fuel consumption is likely to rise substantially. Also, due to a lack of oxygen (which is needed to complete the combustion process), the engine sometimes starts to misfire, sometimes seriously (this misfiring may produce an unusual metallic rattle or knocking when the engine is under load). If the engine is left in this condition for too long, the engine life will be shortened considerably. In the worst case this problem may cause melted pistons and therefore engine failure. The valves in the cylinder head may also begin to stick due to being heavily coated with carbon.

However, other really nasty problems occur when the EGR valve jams closed: without the cooling effect of the exhaust gases, the engine starts to overheat. Over time, this overheating causes the engine oil that feeds the turbocharger to break down. When the engine oil starts to break down, the bearings in the turbocharger fail. When the bearings fail, the turbocharger will fail, and replacement won’t be cheap. If the turbocharger is replaced without solving the EGR problem, the next turbocharger will also fail before too long.

It gets worse: when the engine overheats, more lubricating oil can enter the combustion chamber and the engine can start running on lubricating oil even if the diesel fuel supply is cut off. The engine may then begin to run on its own engine oil instead of diesel fuel. The driver may be unable to switch off the engine except by stalling it. Eventually, the engine sucks away all the lubricating oil and the engine disintegrates.

Arianne

[wimorrison]

I bought a kit for £25 to remove the EGR on my TD5 Landrover because of rough idling, it took 10mins to fit and the Landrover has passed its MOT every year since the EGR was removed, plus the engine is much more responsive.

The EGR on the Landrover is known to cause issues as it sticks causing the engine to always get the exhaust recirculated - what it is designed for - but issues have meant that alternatives have been developed, I wonder if the same will happen here once the cars are out of warranty?

[Gilesme]

So, picking up Arianne's excellent article - VPower is supposed to contain more detergents and lubricants, which make make the valve less prone to fine dust build up/EGR sticking ?

[Flux]

Yikes but thanks Arianne.

Starting to get that paranoia you get when you feel something is going to happen!

Not yet had any issues with mine (at 10,800 miles) but seems like you could seriously damage your engine if it does fail!

I think all these bolt-on solutions that are designed to meet emissions will slowly strangle diesel engines. All sound hugely technical and therefore prone to breakage and guess the prognosis of it happening seems to be dependent on your type of journey - or maybe just bad luck.

I don't use my local dealer any more due to some issues with them and my allotted one is about 40 miles from where I live. So guess if I did have a problem near home I'd have to drive for about an hour to get help.

I wonder if they will replace the EGR anyway for modified one at 18,000 miles service regardless if no issues experienced as it does seen like a matter of time before it sticks or gets gunked up?

[Arianne]

Let's put it this way, even though I had my EGR replaced at about 6k, I will be discussing this with my local dealer when the car goes in for its first annual service in March. If there's a replacement which has been upgraded then I want this version fitted before either my Swiss summer holiday or my next Austrian ski holiday. Engine warning lights, limp running and a dollop of anxiety is not what I paid a shedload of money to experience!

Unsure about the fuel issue - I would like to believe that Shell v-power nitro diesel might help (just filled up with £79 of it today, as it happens) but our first EGR valve still failed at about 6k - and almost all of the fuel for our XC60 is the premium Shell stuff, she's never drunk supermarket fuel.

Personally, I also am beginning to wonder if petrol might be worth considering at some point downstream. So much simpler, more reliable, cheaper to maintain and I prefer the performance of a petrol engine car. Of course, it depends upon your annual mileage, pump prices and depreciation. And petrol engines are seriously out of favour for SUVs when, like many of us, we're buying brand new and selling the cars on to the used market / dealers.

But my annual mileage is due to fall further in September 2015 when, thanks to the Scottish Government, they open the Borders Railway. Instead of driving to work we will be able to use the train (steam trains too!). This will be one of the most scenic 35 mile stretches of railway in the UK, although I remain unsure about the economic business model upon which its supposed to make a profit!

That JLR F-Pace is due to be released with a V8 petrol, according to AutoExpress Will I buy that one? In my dreams!

Arianne

[RoyMacDonald]

That's not the main purpose of the EGR valve. It's to reduce NOx. From Wiki.

In a diesel engine, the exhaust gas replaces some of the excess oxygen in the pre-combustion mixture.[1] Because NOx forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, the lower combustion chamber temperatures caused by EGR reduces the amount of NOx the combustion generates (though at some loss of engine efficiency).[2] Gasses re-introduced from EGR systems will also contain near equilibrium concentrations of NOx and CO; the small fraction initially within the combustion chamber inhibits the total net production of these and other pollutants when sampled on a time average. Most modern engines now require exhaust gas recirculation to meet emissions standards

Petrol engines have EGR valves as well.

From Autospeed...

UK researchers working for the engine component manufacturer Mahle conducted testing on a 2-litre, 4-valves-per-cylinder, direct injected, turbocharged and intercooled petrol engine. The EGR system was of the external type and used a cooler that reduced exhaust gas temp to just 20 degrees C. The system added the cooled exhaust gas well ahead of the turbo compressor (note: so apparently not after the throttle body).

When running at high power outputs, the engine used a modest amount of fuel enrichment and a large amount of cooled EGR to achieve Specific Fuel Consumption up to 16 per cent better than with fuel enrichment alone. Under the same operating conditions, the reduction in NOx was about 30 per cent, the reduction in CO was 70 per cent, and HC was 80 per cent.

[Arianne]

Roy, TBH I didn't know whether petrol engines had EGRs or not. Thanks for the update. My point about petrol engines was a more general one though - about simplicity compared to diesel.

That said, the eye-watering residuals make petrol on an SUV a non-starter. Unless buying used when a chunk of the value has already been taken out.

Arianne