Pro & Cons of EGR Blocking

[batosai]

It depends on the car's tuning. Without EGR, the temps at low-load cruising might increase as the engine "leans out". Some engines can take this, as stock tuning is very rich (hence the smoke... too much fuel entering the combustion chambers), but if your car is properly tuned, it will run hotter.

And no, we don't test NOx. Local emissions centers test hydrocarbon emissions HCO and particulate emissions, both of which will be decreased by blocking off the EGR.

Hi sir Niky,

Can you elaborate what you have said earlier, I'm not familiar with term you used. "the temps at low-load cruising might increase as the engine "leans out". Some engines can take this, as stock tuning is very rich"


Thanks

[rion]

If I remember it correctly, a comment from a mechanic's blog. EGR is suppose to cool down the engine on idle since EGR is only activated on idle and low rpm. some Exhaust is sent back to the engine's air intake thus making the fuel less combustable on idle making it cooler on idle and low rpm.


EDIT: I just remembered, I don't think all vehicles that has EGR is deactivated on high RPM. because when we disabled the EGR by blocking it's vaccum pipe. then put a blanking plate between the exhuast and intake pipe hole. there are still carbon deposits sticking in the blanking plate's exhaust side when we opened it weeks later despite disabling the EGR control. I think it still mixes little exhaust back to the intake on high rpm. while on low rpm/idle a bit many more.

[niky]

If it's open at high load, then the EGR is sticking open and there's something wrong with the EGR valve.

Regarding temperatures at low-load cruising... EGR is active mostly at low-load, low-throttle situations at low to medium rpms. At high rpms, EGR is closed so the engine can make the most power. At low rpms, having exhaust air, which is low in oxygen, mixed with the air-fuel mixture coming from the intake and injectors, allows the engine to burn less fuel than otherwise. In other words, the computer can set the engine to "lean-burn" (where it injects less fuel per volume of air than it normally does).

A short explanation: Stoichiometric ratio is the ratio at which a volume of fuel burns precisely all the oxygen given to it. For gasoline this is 14 parts air to 1 part fuel. If there is too much fuel, this is running "rich"... Running rich has one advantage... the evaporation of the excess fuel draws heat away from the engine. If there is too little fuel, this is running "lean". This causes engine temperatures to go up. A side effect is that nitrous oxides are formed due to all that excess oxygen floating around. What the EGR valve does is dilute the incoming air with exhaust... which has almost no oxygen in it... so that the percentage of oxygen in the intake air is less... so even if you're running at a 16:1 or 17:1 ratio, due to the lesser percentage of oxygen, it's just like running at a 13:1 or 14:1 ratio.

So what happens when you block off the EGR, the air-fuel ratio becomes leaner. This is not a big problem on most vehicles, which are tuned to run "rich". But some vehicles are already tuned to run "stoich" or close to it, so those engines will run hotter. But if your vehicle doesn't have an O2 sensor, I don't think it's a problem.

[batosai]

Ah ok now I understand the principle of having an EGR so what I must do for now is to check the valve of EGR if it is funtioning well and not block the EGR is that right?

[suysuy]

when I discon my EGR, my check engine will light up. I put it back hehe

[gonzo]

Is EGR already on most modern engine like VVTi, D4D of toyota?

I have no idea that there is such function on air and exhaust system.

Thanks

[rion]

myroon na daw ang innova diesel. but revo and older hi-ace wala pa afaik.

[Dieseldude]

Ah ok now I understand the principle of having an EGR so what I must do for now is to check the valve of EGR if it is funtioning well and not block the EGR is that right?

I would first check/block the vacuum line to the EGR valve, then check the valve and control system.

[Dieseldude]

Ah ok now I understand the principle of having an EGR so what I must do for now is to check the valve of EGR if it is funtioning well and not block the EGR is that right?

Correct tayo jan. Good for the environment pa.

[rion]

when I discon my EGR, my check engine will light up. I put it back hehe

the solution to this is not to block the egr control but use a blanking plate. but I wouldn't do it to my new cars. or Maybe I'll use a blanking plate with small holes in it, so it will least catch some carbons and soots. and clean it up once a year.