Car question

[glatt]

Originally Posted by tw

For example, an EGR valve must open and adjust position during normal mode. Same EGR valve must be completely closed during idle. Same EGR valve acts completely different in the two operation modes. EGR valve could be leaking (defect during idle mode). But performs as a completely different device (100% functional during normal mode). IOW the same part has two completely different operation modes.

Your EGR tests said the EGR valve in both operation modes was OK.

When I checked the EGR valve, I could open and close it by sucking on the hose that goes to the diaphragm, but I couldn't see inside the valve to see if it was sealing properly when it slapped shut. Maybe there's a little grit keeping it from closing. I sprayed A LOT of carb cleaner in there so I think it's clean, but I can't know for sure. I suppose I could have tried somehow blowing through the exhaust channel to see if it was blocked. Even after cleaning, there's no way I'd want to press my lips against that surface.