dream02transam

I was checking to make sure my EGR valve was work and as I reved the motor it would not move up or down. So I took off the vaccum line while doing this with my finger to it... no vaccum also i couldnt hear the vaccum and the engine didnt act like there was a vaccum leak. I also sucked on the line going to the egr valve and it moved up and down smoothly . So I know the EGR valve is ok. I think its the solienoid. My only question is what the solienoid attaches to. It has one vaccum line going from the solienoid to it and a 4 wire connector. I believe its called the vaccum switch. Could this also cause it or is this just for ECM information purposes only. the reason I ask is I will check again but I didnt get an EGR code. So if the is no vaccum going to the switch when it should is this switch bad too . Will the switch affect enging operation of just tell me when the EGR is bad... in which case I dont care to replace it. Is the solienoid the most likely cause or can the switch also effect EGR valve operation. Thanks... Erik

V6sucker

the EGR is electronicall controlled on 90-up. The vacuum signal is mute.
On 86-89 the EGR is still semi ECM controlled, again vacuum signal is kinda mute.
85- earlier, it is a vacuum switch controlled. The engine has to have certain condidtions before the switch is activated.
Although there also has to be certain condidtions met before the EGR sees vacuum.

Nocturnall

my egr is all kinds of broke and the only time I get a ses light is over 50mph so I dunno if that's when it kicks on or what...might be hard to watch movement on the egr if that's what's needed.

dream02transam

I checked my codes again... there are none for the EGR. So since my egr valve didnt set any codes I should leave it alone? What conditions must be met to open the valve. I tryied reving it cold and when warmed up and didnt move. I wasnt thinking about that it needed certain conditions so I will have to try again. According to the chiltons it says it is closed at idle and WOT and inbetwwen is open to varying degrees. It didnt say anything about any other conditions, but they arent the best manual and have been know to be wrong before. (example it said my MAF sensor was a hot wire type when on the V-8's are and the v-6's are frequency film) I have tested an egr valve to see if it moved but that was on an 85 which you said was not ecm controlled and this 89 is so I guess i cant go by that. So Should I just leave it alone? Will it alway throw a code if the solienoid or switch go bad? I know it might not if the Valve itself does but I know my valve works. What conditions does it need to open or is this too technical? Thanks for the help.... Erik

CaliCamaroRS

If you revved it in Park or Neutral, the EGR will not open. The PCM has to see the vehicle in gear to open the EGR. If you want to know if the EGR solenoid is working, hook up a vacuum gauge to the EGR valve side of the solenoid and then go drive it. If the gauge moves while you drive, then the solenoid is ok.

Keep in mind, if the solenoid isn't working you should get a code 32.

V6sucker

Typically, the EGR will set off a code if is not working. SO no code, it's a safe bet it's working.

It opens under engine load, in cruise type conditions, at temperature. If I am not mistaken, I even think the car has to be doing over 30 MPH as well.
I.E, going down the highway at 65, engine at 180 Ish, that EGR is open.

Nocturnall

I know for a fact that mine doesn't work, go on the highway, do 70. You don't get code 32 the egr is fine.

TomP

Here's the 85-89 setup:

1. EGR valve
2. EGR solenoid
3. EGR vacuum diagnostic switch.

The three are linked together by vacuum lines. There is a "tee" off the output of the EGR solenoid, which sends one line to the EGR valve and one line to the diag switch.

When the computer turns the EGR on, it activates the solenoid. The solenoid allows vacuum to flow to the EGR valve -and- the diag switch. Then, the computer checks the EGR diag switch (rectangular box with 4 wire connector). It should see a completed circuit. This means that a vacuum exists in the plastic lines between the EGR solenoid, EGR valve, and diag switch.

If the computer doesn't get the OK from the diag switch, it throws up code 32. So code 32 can appear if the EGR valve is broken, EGR solenoid is broken, EGR diag switch is broken, OR if any of those plastic vacuum lines are cracked.

Usually when the 85-89 vacuum op'd EGR valve goes bad, it sticks in the open position. That means after the EGR activates, it doesn't shut off- and when you come to a stop, the car stalls. I had this happen once; after the car cooled down, the EGR would un-stick, and the car would operate normally. Like V6sucker said, it would only act up after I met the EGR conditions (high road speed + low engine rpm + engine warmed up). Finally one day it acted up right outside my house; I quickly pulled into the driveway, popped the hood, looked around at the engine- saw the EGR, checked underneath, and it was stuck open. I fired up the air compressor (with the car still barely running, ready to stall), and as soon as I had pressure, I gave the valve 30psi from my air gun- the valve snapped shut and the engine ran normally again. I bought an EGR valve from Pep Boys, got it home, and noticed it was a generic valve screwed into a base plate- I would've had to snap my vac line to hook it up. So I returned it and dropped $50 for a nice new black original GM one from the dealer.