I have a couple of questions about the EGR on an L69 engine. Its not idleing very good below 500-600 rpm.

1. How does the EGR effect idle, it only throws a code at higher rpm right?

2. To remove the EGR (just for testing) can I use the block off plate and plug the line? is there anything else to do?

3. This thing in the pic below (EGR solenoid?). Has a wire connector and vaccume lines, what is it, and does the bracket need to be grounded? I just have it loose.



Thanks

 

ttt

 

The EGR solenoid is just a computer controlled vacuum bypass. It runs at a "duty cycle" linda like a fuel injector does. But it only runs at 0%, 25%, 50%, 75% or 100% based on ECM control. The more the duty cycle the more vacuum is sent to the EGR valve to control it's opening. What happens to the vacuum that is NOT sent to the EGR? It gets vented to atmosphere- that's the little vacuum line fitting that there is no vacuum line connected to.

The bracket does not need to be grounded.

There should be NO opening of the EGR at any idle speed. Having it open can cause a vary rough idle.

If there is ANY vacuum going to the EGR valve at idle then that little control valve could be part of the reason.

 

Alan,

The EGR is only supposed to operate at part throttle, light load cruise. So the "higher RPM question is somewhat correct, in that the EGR will only operate at an RPM higher than idle, but not a LOT higher than idle.

And for the error codes, there are several conditions that will set the error code.

The ECM will set a code for the EGR if the solenoid is not connected on some later cars.

The ECM must sense a change in MAP when the EGR is commanded open by the ECM. If not, you'll generate the error code as well.

If I can find the test/diagnosis procedure, I'll post it. The EGR solenoid will actually duty-cycle (on most cars) at all times when the ECM is in Field Service Mode, making testing easier.

And to clarify Damon's statement, the EGR side of the solenoid is vented to atmoshere when the solenoid is de-energized. In reading his statement the first time, it sounded like it might imply that the manifold vacuum side of the solenoid valve was vented to atmosphere, which would create a constant vacuum leak.