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[24_Valve]

I'm going to be sealing off my egr valve, some time soon... tin can etc.. question is whether this will increase CO, HC etc. Already trying to get my CO down for 2nd MOT retest and don't want to make it worse.  Should I wait til after MOT?

[24_Valve]

anyone know 

[geoffr70]

I know nothing about this other than what i read in Haynes. It says egr is to reduce emissions, so if you block it off I'd have thought your emissions would go up.

[24_Valve]

thanks geoffr70 that what I'm guessing too Was hoping that other OOF members who have already blanked their EGR might know what difference if any, that it's made to their CO reading? and curious as to whether they leave it blanked off for MOT or not?

[aaronjb]

EGR is there to reduce HC and NOx emissions during cruise states - it should be (assuming it's not broken in some way) closed during idle and high load (rapid acceleration) states.

I don't believe it would affect your MOT test emissions results; at idle the valve is closed so the natural idle test would certainly be unchanged, and I believe the fast idle test is most likely beneath the EGR opening threshold also and would also remain unchanged.

If, of course, the valve is sticking open or leaking exhaust gasses into the inlet manifold when it shouldn't be, then it most certainly could positively affect your emissions.

[24_Valve]

Posted by aaronjb Today at 00:22

If, of course, the valve is sticking open or leaking exhaust gasses into the inlet manifold when it shouldn't be, then it most certainly could positively affect your emissions. 

Hmmm that could be a clue, I wouldn't be at all surprised if it were sticking open because it's about the only thing I've never cleaned or serviced  :-/ do you mean "positively" in the mathematical sense  i.e. raised CO ?? 

[Kneepad]

I suggest you wait until after the MOT. You'll just kick yourself silly if it fails on emmision.   

[aaronjb]

Hmmm that could be a clue, I wouldn't be at all surprised if it were sticking open because it's about the only thing I've never cleaned or serviced  :-/ do you mean "positively" in the mathematical sense  i.e. raised CO ?? 

No I meant positively as in 'in a good way' .. so.. negatively in a mathematical sense  (less CO )

[ballcock50]

Hasn't effected my emissions at mot cost me 2p to do literally 2 x 1p pieces unbolted popped coins over holes and rebolted. Job done.

[geoffr70]

Sorry to hijack another post and for being ignorant. What benefit is there in blocking off the EGR? Thanks

[mark.adams]

The benefit for a smaller engine is negated, apart from not feeding exhaust gases back in your inlet, for a bigger engine however, you could have a performance issue if you are burning previously burnt gases, easily blocked off with the metal from a cut open coke can, cut to the shape of the gasket.

[DaveL]

I'm going to be sealing off my egr valve, some time soon... tin can etc.. question is whether this will increase CO, HC etc. Already trying to get my CO down for 2nd MOT retest and don't want to make it worse.  Should I wait til after MOT?

Have you tried one of the addatives into your petrol, to clean the gunk out of engine combustion? I have had good results with Cataclean and also a Forte product. My ECR was playing up and even cleaning did not cure it. Ended up buying a new ECR from Dealers. Still problems with emissions with mine till I went down the 'chemical' route. Also an Italian tune up did no harm.

HTH.
DaveL

[2woody]

you'll not notice if EGR is working or not. It doesn't feed back enough gas to affect the power or emissions.

the phrase "it's there for emissions reasons" refers to the type-approval emissions test, which is for manufacturers to do before the car goes on sale. This is a very tough test and takes four days to do, using machinery costing £10M +

in detail, the feeding back of a small amount of burned exhaust gas reduces the NoX content of the exhaust under certain conditions. NoX isn't even measured for MOT - the equipment is just too expensive.

actually, smaller engines need EGR the most. NoX is generated at higher combustion temperatures, when the engine is working hardest. The EU drive-cycle for the emissions test requires about 50BHP to run, and so a smaller engine wioll be working harder and therefore producting more NoX

[aaronjb]

you'll not notice if EGR is working or not. It doesn't feed back enough gas to affect the power or emissions.

You definitely notice it on the turbo diesel.. but I agree with you in general on a petrol car (it's just that on a turbo car you end up blowing boost down the exhaust pipe if it's stuck open, and you really tend to notice that from the massive lack of power and billowing black smoke .. ask me how I know  )

[2woody]

obviously, if it's stuck open on a turbo car, you'll notice  :-?