Hi,

I was wondering is it legal to disable the E.G.R system of a car? Particularly in Ireland?

E.G.R is a system that takes exhaust gases into the engine, to cool down the combustion (or something like that) which reduces NOx gases.

Disabling the system stops crap coming into the engine, and increases HP (if car is old, and E.G.R system is clogged up (usual for old diesel cars))

Thanks.

Reference of a clogged up E.G.R pipe, yuck all that crap coming into an engine

It is not likely legal. And your car will run poorly without the EGR valve, because the spark timing will be wrong when it thinks it's opening the EGR valve that isn't there.

Quote from wheel4hummer :

It is not likely legal. And your car will run poorly without the EGR valve, because the spark timing will be wrong when it thinks it's opening the EGR valve that isn't there.

EGR valve is there, but it's blocked to the engine.

And it doesn't run poorly. It runs extremely well, car feels so fast, although, if it's not legal, better change it back

Quote from wheel4hummer :

And your car will run poorly without the EGR valve, because the spark timing will be wrong when it thinks it's opening the EGR valve that isn't there.

Not on all cars... Several run better with it removed / disabled / blanked.

I'm not sure on the legalities (i'd imagine that modifying a car with the intent of increasing emissions breaks something or other...), but you'll have no problem passing a UK MOT with it bypassed, and i've not heard of any issues in Ireland either.

(The EGR bypass is a common 75 / ZT / e46/ Freelander mod)

It is not legal, I've removed in the car with my wife. I modified the throttle body where it was the EGR and now the car works much better.

Thanks Jakg. Well I know many do it on the Citroen Xsara HDi engines, probably because they are more electronic than other diesels.

I guess I will have to try pass the MOT then. Don't want to buy a new E.G.R kit for 120 euro plus

Quote from Jakg :

(The EGR bypass is a common 75 / ZT / e46/ Freelander mod)

It is a common mod on a lot of cars. There are also many for and against arguments. The upshot is, you do not break the law by blanking it. But if the extra pollution fails the MoT Test you'll have to put it back, but I am yet to know of anyone who has had this problem.

Quote from wheel4hummer :

It is not likely legal. And your car will run poorly without the EGR valve, because the spark timing will be wrong when it thinks it's opening the EGR valve that isn't there.

The ECU is a smart bit of kit, it'll know the EGR isn't there and adjust timing to suit. If your car ran a distributor, then for sure it'd knock the timing out so you'd need it altered.

I can feel the ECU working harder, by the turbo working louder.

Rev it to the limiter, and the turbo starts squeaking (it's old, so probably it spinning fast is not a good idea)

Nevertheless it feels like a new car again

Quote from P5YcHoM4N :

The ECU is a smart bit of kit, it'll know the EGR isn't there and adjust timing to suit. If your car ran a distributor, then for sure it'd knock the timing out so you'd need it altered.

I was just going by how it works on my car. The advance is just programmed in. It looks up the value in the ignition table, and then if the EGR valve is open it advances whatever that value is. And if you disconnect the connector so that it knows the valve isn't opening, then it'll throw a code and you won't pass emissions where I live. Obviously it takes experimentation/research to figure out if your vehicle's timing will be corrected when you disable/block-off the EGR!

It's better to do research now than to assume your engine will compensate spark timing wise and suffer detonation and damage your engine. Unless it's a diesel. Then you don't have to worry about spark timing, obviously

Like I said it's a HDi engine, so it's a Diesel

Removing EGR won't increase power, whether it's new or clogged.

Quote from tristancliffe :

Removing EGR won't increase power, whether it's new or clogged.

It does.

When it's clogged up:

1) The turbo stops working usually on Diesels (+HP)
2) The engine might not even want to rev up with it clogged (+HP)



Obviously you don't get more HP than it originally was, when you bought it, but it increases it

Quote from tristancliffe :

Removing EGR won't increase power, whether it's new or clogged.

Unless you get one of the new Vauxhall diesels cars (well made in the last 5 or so years), which enter limp home mode every time the EGR gets clogged. But then around 30 minutes of hard driving down the motorway will unclog it and you will get full power back.

Quote from tristancliffe :

Removing EGR won't increase power, whether it's new or clogged.

It might make a tiny bit power as the engine is not having to burn exhaust gasses as intake air, Tho the difference will be tiny.

In Vauxhall and Ford petrol cars ive removed it on it only really makes the throttle a tiny bit more responsive, Doesnt change anything going flat out in top gear tho...

It did for us

The car would even rev past 2000 RPM.

After blocking it drives well. (Actually it was clogged when we bought it so now it feels like a rocket)

With the EGR blocked, you get no exhaust gas in the intake charge. This will increase power at that throttle/RPM.

However, EGR is not activated at WOT. Thus, if it's working or not, to get more power you simply open the throttle a tiny bit more. It doesn't matter if you have 1hp less than you could have at 50% throttle, because you can just go to 51% throttle (unless, of course, the throttle response becomes particularly bad, but that's unlikely unless you're mapping your own car and ECU).

The operation of the turbo won't be affected by the EGR ports being blocked, as the turbo operated on the exhaust and the intake tracts only.

Then how come my Turbo is working harder? (I hear it squeek)

Also, on the Xsara Owners Club everyone says, if you block the EGR, the turbo does work harder

Quote from PoVo :

Then how come my Turbo is working harder? (I hear it squeek)

Also, on the Xsara Owners Club everyone says, if you block the EGR, the turbo does work harder

Although I could not argue to the opposite, a lot of miss information is spouted as the gospel truth because enough people say it.

Quote from PoVo :

Then how come my Turbo is working harder? (I hear it squeek)

Also, on the Xsara Owners Club everyone says, if you block the EGR, the turbo does work harder

It think it's fair to say that any information gleamed from an Owners Club Forum is likely to be the exact opposite of the truth.

They'll probably tell you their cars are faster on higher octane fuel because 'it burns better' and that lowering a car 'increases grip'.

Your turbo isn't working better (at WOT) after blanking off/cleaning the EGR ports. You just think it is because you've done some work to it and want it to be better, and are listening/feeling for performance more than usual. The same reason people put V-Power in their car and think it's more powerful immediately.

V-Power isnt really bad. I once got a full tank of V-Power Raving for Regular money due to some advertising thing, and I did 80km more on that tank than on regular (450 normally, 530 with V-Power) And that was in my 1.0 Eurobox, driving the same commuting routes.

For the EGR thing, shouldn't fuel consumption go up? I mean the recirculated gases work a bit like the nitrogen in nitrous oxide, filling the cylinder with none burnable volume. If you block it off, all that space can be filled with O² rich air, that in turn needs fuel to not lean out the engine (when burning petrol).

I agree. V-Power can improve economy and range. It does on my car to the point that it's cheaper per mile to use V-Power over standard unleadeds.

EGR is quite a complex process really, as it changes the specific heat of the charge,( charge cooling) replaces 'fresh' air with oxygen from the exhaust, and gives a second chance at burning some of the remnants from the first burn. Only a fraction of the exhaust gas is recirculated. EGR reduces power (for a given throttle opening, but as I said, if you want more power you just open the throttle a bit more). EGR never works at wide open throttle.

Blanking it off will slightly increase emissions, and slightly decrease economy. The former might be enough to fail an MoT (or whatever your annual inspection is called), the latter is probably immeasurable.