Vetteatlast

what kind of symptoms could expect if I had a malfunctioning EGR valve - would it cause a ruff idle problem??, there are no codes

jimg's'93

Mine had a rough idle and no codes. But I did find my EGR was not holding vacuum, most likely a dry-rotted diaphragm.

MotorCity_87_C4

My EGR was rotted also and wouldn't hold a vacuum. It would throw an intermittent code 32

BobRR3

the EGR does not energize unless the you are in a cruise mode. It does not activate when idleing or, when accelerating. the reason for a bad idle (if you have a defective bladder ) the result is a vacuum leak. The vacuum leak would then be causing the rough idle. If you have this problem, Replacing the EGR would solve it. You can test this by pintching, or disconnecting the vacuum source to the EGR. If the problem goes away, That's your problem. If not, you need to look elseware

94z07fx3

An EGR valve that won't open when it is supposed to will cause high NOx emissions. An EGR valve that won't close when it is supposed to will cause rough idle and/or engine dies. The most common failures would be carbon buildup keeping it from closing or a leak in the vacuum line or diaphram keeping it from opening.

BobRR3

If the EGR valve that is stuck open, The car won't idle at all. It didn't sound like this was the problem with this specific post.

WW7

To check for a cracked diaphram just spray some carb or TB cleaner under the EGR valve, if the idle picks up you have a cracked or leaking diaphram.Also as far as a stuck egr, it depends how far open the egr is stuck,if its stuck wide open the car will surge and stall,if its stuck slightly open it will idle ruff and likely surge at steady cruise speed, if its stuck closed you will have higher temps in the combustion chamber which will very likely cause pinging..If you have a (factory service manual) it tells you how to test the EGR....WW

HughG

Just wondering... If you were to disconnect the EGR all together would this cause any problems? Is the EGR necessary for proper running?

Tommy T-Bone

Yes and yes.

engle1147

Notice the lack of a hole where the vacuum line goes this puppy was stuck in the "open" position also.

flcarrell

How do i know if the EGR valve sensor is bad. I installed a new EGR and still have a rough Idle and hard starting. It even has a dead spot now and missing under a load. Any ideas out there?