I failed an emissions test. The first time I took it in, I forgot that the vacuum hose to the EGR valve was off and I failed the NOx with 3.8xxx out of 3.000. I took it again today with the EGR hooked up and got 4.8572 out of 3.000. It's actually higher than the first time:banghead:

What's going on?

HC: .6692 out of 2.000
CO: 2.1944 out of 30.000
NOx 4.8572 out of 3.000

I failed an emissions test. The first time I took it in, I forgot that the vacuum hose to the EGR valve was off and I failed the NOx with 3.8xxx out of 3.000. I took it again today with the EGR hooked up and got 4.8572 out of 3.000. It's actually higher than the first time:banghead:

What's going on?

HC: .6692 out of 2.000
CO: 2.1944 out of 30.000
NOx 4.8572 out of 3.000
Clean the EGR tubes inside the throttle body with a stiff wire.

Clean the EGR tubes inside the throttle body with a stiff wire.

I should mention that the car is an 86 deville 4100.

I attempted to do that once but on my car it looks like you have to take the throttle body off.

I should mention that the car is an 86 deville 4100.

I attempted to do that once but on my car it looks like you have to take the throttle body off.)

If the tubes are clean (they should be on 4100) the problem may be the EGR valve and/or EGR solenoid. Make also sur eall other vacuum lines are intact.

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If the tubes are clean (they should be on 4100) the problem may be the EGR valve and/or EGR solenoid. Make also sur eall other vacuum lines are intact.

I replaced the egr solenoid 2 years ago when I couldn't pass but it didn't help. What if I just bypass the solenoid and connect the vacuum tube directly to the egr?

I replaced the egr solenoid 2 years ago when I couldn't pass but it didn't help. What if I just bypass the solenoid and connect the vacuum tube directly to the egr?
You can try it. It may open the lazy EGR valve since the solenoid reduces the vacuum supply to the EGR valve, but you will get very rough idle and even stall. You can pass emission test though that way and when bring it back.

Also... try to "exercise" the EGR valve by pressing with your fingertip the diafragm in the bottom of it.

It isn't as easy as hooking vacuum directly.

The EGR works in strange ways. And even if the constant vacuum kept it fully open, then the car woudl stall while idling (too much exhaust woudl be getting onto the fuel mixture). So, you have to really fix it properly.

Helm Factory Service Manual has nice troubleshooting instructions which walk you through all the steps needed to determine what is wrong.

Peteski

It isn't as easy as hooking vacuum directly.

The EGR works in strange ways. And even if the constant vacuum kept it fully open, then the car woudl stall while idling (too much exhaust woudl be getting onto the fuel mixture). So, you have to really fix it properly.

Helm Factory Service Manual has nice troubleshooting instructions which walk you through all the steps needed to determine what is wrong.

Peteski

I had it hooked up directly and it idled rough but didn't stall. I didn't drive it though.

You might also try retarding the timing to get it to idle well. It'll also make it run cleaner.