what are symtoms of a bad egr valve ?

I have a rough idle ( not real bad ) with my 02 blazer with 53000 miles on it. I just replaced the o2 sencors a week ago it runs better over all but still have a rough idle. I was told it could be the EGR valve? what would be the symtoms of it going bad ? and what can cause a rough idle . Thanks

When I had EGR problems it was a really rough idle and it stalled when I slowed down as well. I didn't replace the EGR though...I just had it cleaned and had a filter put in it...only cost about $20 or $30 I think...much cheaper than replacing teh whole EGR.

yzf, on an '02, a bad EGR would most definitely trigger a "Check Engine" light

Good point...I forgot to mention that I had my check engine light on when it happens...

I would agree that a BAD egr would trigger a check engine light, but a dirty one may not. It is possible that some carbon has stuck the valve partially open. The gasket for the egr valve is under $2. If you think that this may be the case, go grab yourself a gasket, take it off, and thoroughly clean the pintle area of the valve.

How is your gas mileage? If it is crappy, then you may have a leak in your fuel injection spider which is located under the upper intake plenum. A leak here would cause a rough idle as well as some other symptoms (that may or may not be noticeable depending on the extent of the leak) while accelerating.

Yeah, I'd check any vacuum hoses going to it, make sure none are cracked or leaking. If they're good, take the valve off and clean the area with carb cleaner. Spray some down in the tube that goes to the manifold, make sure there are no large carbon deposits. When you put it back on, throw a new gasket on there and see how it does.

I agree with Kyle, carbon could be keeping the valve from closing all the way so it's running rough, while at the same time not triggering the Check Engine light.

Another sign of a bad EGR valve is a strong exhaust smell coming from the front of the car (provided you don't have an exhaust leak elsewhere).

Where is the EGR valve located ? I think i see it on the passenger side of the engine but im not sure. Also , When do you need to change the plugs ,cap and rotor ? ( I have 53000 now ) Can these items cause it to idle rough ? My gas milage is around 19 mpg, Thanks for the help guys.

depending on the use in that 53,000 miles, it is possible that the plugs, wires, cap & rotor need changing. A worn cap/rotor could cause a rough idle, but it would also result in misfires under load (more) and possibly worse symptoms when it is wet outside.

If you are getting 19mpg, then I would lean away from a fuel leak. The EGR valve is located directly on the front of the engine between the throttlebody and the water pump. It is about the size of a soda can, has an electrical connection on the top and is held on by 2 bolts.

I see you are from New York , What part ? I am from New York also.

I currently live out in Byron, NY, just west of Rochester. My wife, son, and I will be moving back to our home county (Seneca County in the Finger Lakes) in another month or 2. I just got hired by Goulds Pumps in Auburn, NY.

YZF. had the same thing on my blazer and messed around way too much with all those sensors and stuff. Take Kyles advise and pull the plenum first and take a look at the CPI fuel lines. I say this also because when I pulled mine there was a crap load of carbon in the ERG passage as well that could have broke loose and plugged up the EGR valve again. Don't know much about your particular year Blazer but it only took me about fifteen or twenty minutes to pull the plenum off mine. As soon as I did I saw the pool of gas and I had a small leaking in the CPI feed line, fixed it and it runs like a champ now. Its also, on mine anyway, easier to take off the egr with the plenum off.

Good luck
Geoff

Where about's in NY are you located? If you are close by, I could stop in (or you could stop by my place - even better idea...lol) and I could hook up my fuel pressure gauge and my AutoTap to see what could be the problem. I can diagnose a leaky CPI unit without pulling the plenum.

VMX, the plenum on the newer vortec engines is a bit more difficult than on your motor. It's plastic and has much more crap around and on it.

I am from Utica New York , about 3 hours east of you, So sure you can stop by if you like

I have a 94 S10 Blazer that recently needed a new pressure regulator (obviously gas in oil) and ran great for three months. Suddenly code 32 EGR error(ran extremely rough at idle..like bad vaccum leak)....spent the $175 at AZone, put on and problem fixed.  Easy job...approx 45 mins total.

Ok a dafty online here with major cash put in to my crap running '95(all sensors,plugs,rotor egr replaced) BUT
 
what&exactly where is this plenum you speak of located? is it the piece where the EGR bolts onto?What is this spider thing supposed to look like?i'm so fed up with my still new looking blazer..kicks'n'farts throughout entire driving range..ugg

Wow...  antsnake brought back a thread from the grave!! 

blzR, please run a search for 'CPI' or 'spider' and you should find more than enough pictures...  We even have a HOW-TO on replacing the CPI spider!  Good luck

ExcellENTO Swartlkk!! didn't think of doing search,i betting this may help out a lot!