alex-z28

also how hard is to replace it if its bad?

whopper

start car,push in on diaphram inside of valve,car should almost die.if rpm doesnt seriously drop,valve is bad,if it sounds like you are choking the **** out of youre car thats because,well you are,but then valve is good.but just because valve is good doesnt mean another component isnt failing.what kinda problems you having?

alex-z28

my engine light is coming on only in 6th gear, also where is the diaphram located.

shoebox

That will prove it is not sticking or possiblly stuck open, but does not prove that it will open with vacuum. The diaphragm could have a hole in it and it would act the same as you describe when you pushed on it. If you use a vacuum tester on it, it should hold vacuum.

JSK333

Where is this diaphragm? Truly on the valve or on the solenoid?

Because I can't feel anything that will "push in" on the valve on the rear of the manifold.

I'm wondering if my EGR setup is bad too, cause of a stumble. Can't tell if it's tuning so I want to rule out EGR first.

LS1_03

Nevermind.

shoebox

EGR

You can see and push the diaphragm in from the front side. There is just enough room to get a finger or two in there. Be careful if your engine is hot.

JSK333

Rob, by front side, you mean the side of the valve closest to the front of the car?

If so, then I think I know what you mean... like little indentations in the valve where you can fit a finger or two?

If that's the diaphragm, and it won't move at ALL when I push on it, does this mean the valve is dead? I mean, it feels as hard as the outer part of the valve. I am checking it when the engine is off. Would it be differently with the engine running, or is it still a sign of a bad valve?

Thanks, and sorry for butting into your thread, Alex.

shoebox

Yes, I mean toward the front of the car. The back is solid. It can be difficult to push in because there is a spring in there. The closer you can get to the center of it, the better.

Possibly even better/easier is to use a vacuum tester to put vacuum on the valve and then you can watch if it moves when the vacuum is applied. Then you will know if it holds vacuum and also that it is not sticking.

Wild1

Great illustration!!! So, when vacuum is applied to the EGR while the engine is running, it should stall. Right? Is this because of the rush of excessive air?

TobyZ28

I think its lack of air, the engine would spin faster the more air enters the manifolds...

(Someone correct me if im wrong

I'm also interrested in checking my EGR...

I just did my PCV valve, the old one looked sorta ok, but was pretty gunked up. Getting a pair of needle nose pliers helpd with that a LOT.

Wonder if my EGR Is ok, i'm troubleshooting a spurratic stumble at low rpm as well and have heard a bad egr could lead to it

chasmanz28

if it is the egr valve didnt gm have a recall on it

shoebox

At idle if you open the EGR, you will notice a rough idle or it will die. That is because you are adding exhaust gas and not air.

Wild1

Didn't mean to throw a curve... thanks for clearing that up Shoebox. So, by applying vacuum to the EGR... we are increasing the amount of exhaust gas entering the intake. That will add "spent" exhaust gases into the intake reducing the amount of burnable air causing the car to stuble or die.

TobyZ28

Ah yes clarity So i guess i kinda was right, just that i probably meant air as in burnable air