I think I accidentally have narrowed the popping or ticking sound that I get when the engine is cold.

 

I had the EGR off today to check and see if it needed cleaning and tested it by pulling a vacuum on it. When I released the vacuum, I heard the valve make the exact same popping or ticking sound. Now I am waiting for the engine to get cold and check to see if it does it with the vacuum line going to the valve blocked with a ball bearing.

 

Question is, will this cause the puter to throw a code, or cause any loss of performance?

 

Then to figure out, if and why there is vacuum to the EGR when it is cold.

 

Oh yeah, what is a BPT valve? It is connected to the EGR vacuum.

BPT is Back Pressure Transducer. I know what it's called, just exactly what it does I'm not sure. (never bothered to find out) But I'm pretty sure it has something to do with the opening and closing of the EGR under certain conditions.

 

The ECU may open the EGR valve to test for operation after initial start. Though it should not open normally until the engine is at cruising speed at "steady" throttle. Under mid range RPM the mixture tends to go lean under light throttle. Lean mixture leads to high combustion temps, creating higher NOx emissions.