But where, EGR Valve is new, Solenoid used 1 year only, recently tried changing modulator, the result is the same. I will test EGR Valve first. I tested solenoid 2 days ago, seems good.

 

Where what?

You only need to turn off the EGR valve system so the valve is closed. The engine will run OK with the valve closed. To turn off the vEGR unplug the electrical connection to the VSV valve or remove the vacuum hose from the VSV going to the modulator and plug the hose.

If the EGR valve is new then assume it not plugged up with carbon to stay open.

 

I tried that just now, it was the same bad. But when I block the hole from EGR valve to intake manifold, it become good. Maybe it is just newly bought EGR Valve is bad.

 

I took off the EGR Valve, blow it from import, nothing come out off out port, so it is good. when key is off, I can blow from modulator output to EGR vacuum control input. But when I put key in, turn to "On" position, I cannot blow through. I can't start successfully without put fan on. But when I put fan on and start it, I can't blow through. Then I turn fan off, with engine still turning, though rough, I can't blow through. From here, seems else triggered smog got into engine and disturb it, or the computer was stupid, or idle air control valve performance not good enough.

 

At least, one thing is sure: At least Two factors lead to idle problem and code P0172, 1 is spark plug tube seal, another is EGR system. I bought the modulator, and returned it, because problem was still there. This is because I didn't solve tube seal. Maybe I should order modulator again.

 

I tried to blow modulator smog input, nothing come out from other port. Seems no problem

 

My car is 1996 toyota Camry 2.2L, I got a used EGR Valve and pipe from Junk yard, because 1996 one on my car EGR Valve and pipe I could not separate them. And it did worked for at least half year. Could it be the newly bought EGR Valve performance not as good as discribed?

 

I've already threw away the used one I got from junkyard.

 

EGR Valve to intake manifold, this morning I tried metal sheet to stop smog, significant improve. Then a sheet of paper, yeah, still good, though I expect it will torn the paper, but not. So I used napkin gorse, no, because the air can pass through, even without torn it. Then back to paper again, ****, this time as bad as without it. Then with metal sheet again, ****, as bad as without it. Why? Then I checked battery, it was 12.1*. That's low. I took off battery to recharge it.

 

After I recharge the battery, I only found it was raining. So I have to pack my car up, otherwise tomorrow it would be trouble to get to work, and my car's driver's window was down. I put on the battery quickly. I tried 4 times to close the window. there were still metal sheet in between EGR Valve and intake manifold, but when I start up, it died off. What the hell! Anyway, I found I can drive it to work tomorrow anyway.