EGR valve

[Agent_zed]

Actually, no... the purpose of EGR is to reduce the amount of oxygen in the mixture thereby lowering the combustion temperature and as a result producing less NOx. The soot and other particulates that are re-introduced as a by-product are undesirable as their abrasive nature can shorten engine life.

sorry yeah getting my PCV mixed up. Modern deisels have cats to remove the soot.

Either way if you remove the EGR valve and/or DPF you will most likely be breaking the law Modifying your vehicle’s emissions: the legal, safety and health implications and could be fined £1000. Along with that it would be likely that you would also find you are uninsured as your vehicle has been modified.

Does anyone really believe you will get 20% better fuel economy? The valve only works in very specific conditions so it would have to have an even greater negative effect to reduce overall efficiency by 20%.

 

[MikeJhn]

I live in a Rural district and can never understand why Farmers leave their Diesel tractors and vehicles ticking over all day when not in use?

 

[Owd Jockey]

I have an Avensis D4D engine and have to clean the EGR valve out every now and then. If you do alot of of urban driving stop/start etc. The soot builds up in the valve, leads to poor acceleration/mpg and sometimes a P-Code. Fortunately, for me, the EGR valve is very easy to get at, so no probs in cleaning it. Wynns do an EGR cleaner in spray form which you need to actually remove the valve for. My car always runs better after a EGR clean, always a good idea to follow this up with an Italian tune-up!

 

[MF1000]

Urban driving is the death knell for EGR valves and dpf filters ….both need a good spell of continuous fast (but legal) driving to burn off sooty deposits

 

[Spectric]

But the point of the EGR is to recycle unburnt particulates back into the engine to be fully burnt.

EGR is only active under certain driving conditions and it's purpose is to reduce combustion temperature which reduces the chemical production of NOx . It simply replaces a percentage of incoming oxygen with inert exhaust gas which slows the burn. Now the big question is has it really delivered ?

A clean engine is an efficient engine and we are actually using EGR in petrol engines to help solve a problem we created in the first place, ie unleaded fuel. The lead in petrol slowed the rate of burn during combustion, now we have no lead and lots of problems with EGR valves and associated systems.

Modern deisels have cats to remove the soot.

The particles are removed by the diesel particulate filter which is itself kept clean by the regen process, it burns of the particles !!

On my first diesels with EGR I simply removed the connector from the EGR solenoid and ran them for in excess of 200,000 miles with no problems, now the newer diesels throw a wobbly and bring the management light on and often drop into limp home mode so you have to get the EGR mapped out and the DPF punched through.

A way to look at EGR is that if you are a runner then you really want to breath clean fresh air to produce maximum energy, you would not run a pipe from your rear end to recirculate any digestion gas back into your intake.

 

[clogs]

EGR = another cock for a s/rubbish engine design........
more junk to go wrong....may well have worked in the lab but not in the real world......
anyway it's only to pacify those in power who know nothing.....

 

[Agent_zed]

now the newer diesels throw a wobbly and bring the management light on and often drop into limp home mode so you have to get the EGR mapped out and the DPF punched through.

You don't have to do either of those things as breaking those parts is against the Regulations 61(7) and 61A(3). Unless you happen to be using your vehicle off road.

 

[Dibs-h]

Still see modern D's beltching smoke.....so much for electronics.....

For passenger cars (and vans with the same engines) usually 2 causes:

1. There is a leak in the intake piping from the turbo (if it's turbo charged) to the intake itself, after the air mass meter, so the air is leaking out and the ECU is effectively over fueling the engine. VAG brand diesels have this from time to time and it's one of the rubber pipes in the intake. Replace the cracked\leaking pipe and no more black smoke out the back.

2. The DPF has been "removed" or visibly still there but cored out, the ECU re-programmed and a crappy remap at the same time, so black smoke out the back.

 

[Spectric]

Also the common rail injectors can leak, they are really cheap & nasty compared to the mechanical injectors of old and unlike them cannot be overhauled or new pintles fitted.