Okay, I'm new to this thread, I have an 88 firebird, 2.8 v6, auto. I have been getting horrible gas milage for the past few months, 220 miles to the 16 gallon tank, comes out to be about 13 or something...I'm not a lead foot, nor do I idle in traffic all day long. After a while, I was getting sick of the milage, and had a friend look at it. He discovered that the one of the vacuum tubes to the EGR valve was cut, the ones that goes to the vacuum I think it is. I'm just wondering, where is the vacuum located? It's not the tubes on the back of the Intake is it? Because if I hook it up to that, the EGR valve triggers the EGR and opens the selonoid up...killing the engine with exhaust...If anyone could help and/or provide a picture of what I"m looking for, that would be great! Thanks in advance!

EDIT: Car also dies at stops, and will randomly stall while idling...

 

Most likely the diaphgram in your EGR is deteriorated and collapsed, or the check valve is stuck. Someone cut it because it kept killing the motor instead of fixing it. Replace those, and you should be able to re-apply vacuum to your EGR, you'll probably pick up mileage.

That is probably not the only problem though, 13 is pretty bad for these sixers. I get about 19 in gridlock traffic. Somewhere around 25-26 overall.

 

It attaches to the vacuum port on the throttle body. See pic. Make sure you attach it to the port in the pic, and not the other one next to it. If you attach it to the other one it will not operate the valve correctly, due to a difference in vacuum characteristics.

 

Okay, I've checked all three connections...one goes to the EGR selonoid, and one goes to the throttle body...then the other one is cut...so the picture you sent me is one that's already connected...right now I have it disconnected, and I have a peice of metal blocking the exhaust going into the EGR...while accelerating, my car would sputter, and if I accelerate too fast, the car would die..the diaphram works properly on the EGR, I tested it with a tube and sucking and blowing, and it functioned propery...I still need to know where that last tube goes

 

EGR shouldnt stall the car out. it sounds like youve got something else going on there. even if your EGR valve is stuck open(mine was at one point) it shouldnt stall out. there isnt enough recirculated exhaust to cause that. maybe a stumble or something, but not a stall condition. are you throwing codes ever? if so, what codes?

 

I forget which number it is, but I referenced my book and it was the EGR one, poor vacuum, poor electrical, defective ECM.

 

Thats a code 32.

The EGR WILL stall the car out, believe that. You need to apply vacuum to that EGR valve and get the car to run like that.

"Sucking and blowing" is not an adequate test for the EGR valve. Bust out the Haynes or Chiltons and go through all the steps (theres quite a few different ways to test all circumstance of function for the EGR). Those kind of EGR's are usually so cheap I just buy the damn things and toss them on anyways, there is a spring in there that wears with time. The diaphgram does the same. And sometimes they don't hold vacuum well.

This is not a simple vacuum leak either, that would make you idle a little high, but I doubt anything beyond that.

Change the EGR, if it has no change, report back. You can always take the thing back if the few bucks comes at a bad time.

 

Man, all I want to know is where that last tube goes...I know it's the EGR valve because one of the hoses is cut! I have the tube that goes to the throttle body, and the one that goes to the EGR...the last one says it goes to the vacuum, which I can not locate.

 

Calm down, this is basic stuff.

The "hoses and stuff" attached to the rear of your intake IS vacuum. vacuum is NOT a location or a component, it is the natural suction your motor creates. These problems are NOT due to a vacuum leak. Not having vacuum to your EGR at all could also produce the same symptoms, but you already said when you apply vacuum to the EGR it stalls. That indicates a failing EGR valve. Unless you misinformed us in the first place, this is more than likely the case.

Can I be any clearer?

Hook it up to any vacuum at the rear of your intake. If the hose is cut, simply re-attach it with a new piece of hose. Make sure all other vacuum lines are hooked up properly or at least have the hose plugged off with a screw or something.

It doesn't matter which vacuum source you hook it up to, it all pulls the same vacuum, varying with engine load and RPM.

 

Applying vacuum to the EGR will cause it to stall if the engine is at idle. This is normal and does not indicate a failing EGR. Also, the EGR is designed to run off the vacuum source shown in the picture above. By hooking it to the correct vacuum port on the throttle body it will receive vacuum at the proper intervals. For example, that port does not produce vacuum at idle (so that EGR does not open and stall engine), but instead produces various levels of vacuum dependent on engine speed.

 

Wow, long time since I've been in here... don't let your frame rot out, that's all I can say... [man I miss my car]

Anyway, for the EGR, yes it can stall out your motor- but only if the EGR gunks up so bad with carbon and/or rust so it sticks open.

EGR only works when you're at low-throttle, high-road-speed, engine-warmed-up conditions. If you're just driving to work and back, then the EGR probably isn't the cause of your mileage troubles. You could leave it blocked off. I used to get about 13-15 mpg on my '86 Firebird 2.8, but then again, I have a lead foot ... EGR mainly just keeps your emissions low as far as the NOx requirement- NOx's increase as cylinder pressure and cylinder temperature go up. EGR lowers NOx because exhaust gasses can't burn (less of an explosion, so less temp for combustion = less pressure).

But that should be fixed, so:

EGR has three components, the EGR valve, EGR solenoid, and EGR vacuum switch. EGR valve itself should go directly to the EGR solenoid (looks like a canister near the EGR valve, on the same mounting plate as the EGR valve and ignition coil). The computer controls the EGR solenoid. The EGR solenoid Tee-s off to divide it's "output" between both the vaccum switch and valve.

So the valve and vacuum switch see the same vaccum pulse from the EGR solenoid. The computer checks the vacuum switch, and if it sees vacuum, it assumes the EGR valve also saw vaccum.

So a break between the solenoid T-connection and vac switch/EGR valve will cause a 32.

First make sure your EGR solenoid is connected somewhere- is it?

 

See the images I've attached. The first one is the routing for your car. The top nipple on the EGR solenoid is the one that goes to the EGR valve and the EGR Vacuum Sensor. The bottom one is the vacuum feed from a ported vacuum sorce at the Throttle Body.

The second picture is how you can "re-route" the lines to bypass the EGR and not get a code.

Now, this does not apply if the solenoid is busted, that's a whole nother story and I can tell you exactly how to test it if you wish.

 

Thank you!
I had tried a search before but this combo finally got me the answer I needed on where th egr hose to selonoid hose went!

Hopefully, the idea follows on a v8