EGR Question

[chaseincats]

Hi,

I tested my EGR by connecting the BPT valve and later the EGR valve directly to intake vacuum (my thermal vacuum valve isn't working) and the engine almost immediately died and the EGR valve made this strange whistling noise.  Any idea why this happens?  The engine was at operating temp in the video: https://www.youtube.com/watch?v=hTZni7rL87k

[Captain Obvious]

Under certain circumstances, exhaust gas is intended to be ported into the intake stream to reduce some exhaust emissions (compounds of nitrogen). Now about those "certain circumstances"...

Those certain circumstances never include "at idle". At idle, the EGR system is disabled because it tends to make the idle unstable. And when you're not at idle, amount of vacuum applied to the EGR valve is modulated by the BPT valve so that the higher the engine load, the more exhaust will be recirculated.

I'm thinking that what you have done is applied 100% full open exhaust recirc under conditions where there should be zero. And the engine doesn't like that.

Here's a bunch of EGR and BPT theory in this thread:
https://www.classiczcars.com/forums/topic/47123-egr-system-theory-behing-bpt-valve/?