What triggers EGR??

[MMamdouh]

i know whats an EGR and what does it do... i am asking about the trigger for its work

it is supposed to kick in when exhaust gases are hot enough to produce NO gases and as far as i have seen daewoos got no EGT sensors or so and that makes the ECU's decision based on something else other than exhaust temp and i wanna know what isit?

i thought it might be a combo of coolant temp, TB position, RPMs and maybe car speed but i am not sure... got any idea??

MMamdouh

[exist3nce]

I don't know the exact triggers, but I believe it would usually kick in during light load and moderate RPMs, say your cruising speed for highway.

[Turtle_Wax]

It's operated by ecu, so must take the readings from the various sensors. The amount of egr is controlled by variations in vacuum and exhaust back pressure. The valve opens when engine has warmed up and above idle, although I think it shuts at wot.

[Damic]

Engine on my Lanos is with simple EGR triggered by vacuum hose. The other more sophisticiated EGR's are electronicly triggered maybe with some RPM sensor.

[Turtle_Wax]

The vacuum pipe that connects the basic type EGR goes to a black plastic valve thingy (not sure what it's called) and then to the TB. There is an electrical multiplug connected to this plastic valve, which is controled by the ecu to allow vacuum to reach the egr when it's needed. Well I think that's how it works.

[PrecisionBoost]

Yes.... it's usually taking coolant temperature into consideration and it can tell if the car is under load via the vacuum port ( so basicly it only opens up when the car is warm and driving under load )

If the EGR opens up at idle it would instantly stall the engine.

Some of the newer cars do it through an electronic valve.... which means the ECU decides exactly when to open the EGR.