Hello, I'm a new member here, and can't seem to find any threads concerning my problem. I have a '95 Z28 and my service engine light came on. My local dealer checked the codes and said it was an EGR problem, and my neighbor confirmed that the valve was indeed "sticky." He then told me to just purchase a new one, and the price for an original GM part is around $120. When I checked at Auto Zone and Advance Auto, they offered a BWD brand EGR valve, but the price is about half of what the factory valve is, $65.

I was just wondering if it was necessary to buy the factory valve, or if the aftermarket valve will perform just as well. It just seems like there is a reason for the huge price difference.

Thanks in advance-
Nick

 

I have it at Napa for $67, its made by Standard. If your worried about quality but dont want to get the GM, Standard makes a good product. I have a very low rate of failure on our egr's.

When you replace it, make sure you clean any carbon out of the tube and manifold passages. It will make sure everything will work as best it can.

 

Welcome to CamaroZ28.com!!

First, let's make sure it's the valve.

Which EXACT trouble code did you get? There are two codes for the 95 EGR system - DTC 27 for the electrical circuit to the EGR vacuum valve, and DTC 32 for lack of EGR flow. If you got DTC 27, it has nothing to do with the EGR valve. It's for the wiring or the coil in the EGR solenoid.

If you got DTC 32, could be a problem with the EGR valve, but it could also be due to 1) plugged EGR passages in the intake manifold, 2) a sooted up pintle on the EGR valve (can be cleaned) or 3) the vacuum supply to the EGR valve, involving the vacuum hoses from the intake manifold to the EGR vacuum solenoid, and then to the EGR valve. Could even be 4) a cracked corrugated tube from the passenger side exhaust manifold, or 5) a problem with the MAP sensor, which is what the PCM looks at when testing for flow through the EGR valve into the intake plenum - these two causes are unlikely but possible. Then there's the possbility that you are running an exhaust system with very low back-pressure, which is reducing EGR flow.

And, if the EGR valve is "sticky" it might respond to cleaning with brake cleaner.

Check first. Don't spend money unless you have to.

http://shbox.com/1/egr1.jpg

 

Maybe I'll have to run in to my local NAPA store today and check it out! Thanks for the cleaning info too. It is a difficult area to access though.

 

Not sure the exact code they got, but my neighbor is the service manager at the dealer and he pushed on the diaphragm when my service engine light was on, and he said that it wasn't easy to push and that it's probably worn out. My car has 48,000 miles on, and i'd imagine that would be the original valve.

Sorry about that double post!

 

The fact that the SES light is on has nothing to do with how hard it is to move the valve. It's not that easy to move the diaphragm. That's why the surface of the diaphragm requires the large housing.

The SES light is on based on a diagnostic routine that was run last time the engine was operated under the specific conditions that allow the test to function, and flow was not detected via changes in MAP reading, not because of valve position.

The more effective way to test the valve would be to apply full intake manifold vacuum to the hose the goes from the EGR solenoid to the EGR valve (in effect bypassing the solenoid). Since EGR is not used at idle, applying a vacuum to the valve should cause the engine to stumble. If it didn't stumble it would be pointing to the valve.

Since you've already decided to replace the valve, hopefully your service manager can can you a break on the factory part. If not, gmpartsdirect.com sells it for $79.

 

Yeah, I pushed on the diaphragm, and when I push it in at idle, the car almost shuts off. It's hard for me to actually work on the car myself because I have limited space and limited tools to work with! Guess I better get with the program if I'm gonna own a 90's American made car haha. Have a problem with the driver's mirror too. One cable snapped out of the plastic behind the mirror, and it looks like the only fix is to buy a new mirror/cable system. Mine is the manually adjustable mirror that uses the "remote" stick or whatever it's called.

 

Forgot to post an update when I got this fixed. The EGR was indeed worn out and off center. After replacement, my SES light was still on, so I also had the solenoid replaced. Turns out that about a month or two later, I finally checked the fuses for some reason, and discovered that the air pump fuse was bad. It wasn't blown or anything, just had a slight break in the metal. As soon as I replaced it, the SES light went away, and the car ran fine ever since. I guess it goes to show that it's important to check the simple things sometimes.

 

How did you determine "The EGR was indeed worn out and off center."? What part was off center? Did the old valve open when a vacuum was applied? Did you even try that? And, since replacing the valve didn't eliminate the code and turn out the SES light, it is highly unlikely that was the problem.

Then you replaced the vacuum solenoid. Did the SES light go out then? If so, that was the problem. A simple recheck of the specific trouble code would have answered that question. Did you recheck the code as suggested?

The next event was unclear. Had the SES light gone out with the replavement of the solenoid, or were you still looking for the reason it was still on? Or did the light suddenly reappear?

" It wasn't blown or anything, just had a slight break in the metal.". If the SES light was on, and the code was for the AIR pump circuit, the fuse was bad. Again, did you actually check for codes, or did you just keep driving around with the SES light, hoping it would suddenly go out, or you would accidentally find the problem.

It really seems that if you had followed the suggestions that were offered, rather than playing "parts replacement roulette", you would have found the actual problem, and saved a lot of time and money.

 

The code was first checked at a dealer, and they told me it was an egr code. When we (neighbor mechanic) took the EGR off, the actual valve wouldn't close because the diaphragm was worn out and causing the little rod inside not to close fully, so it was always stuck partially open. After that, the light was still on, so we assumed that the solenoid needed to be replaced, since the valve replacement didn't solve it. We were stumped after that, and figured that the code was still the same since the symptoms were the same as before the replacement (SES light and both fans run high speed.) I don't have a code checking software (which I should probably get) and I didn't go back to the dealer again. It is possible that the fuse and EGR problems were like a chain reaction?

I did look at the advice, although at the time I didn't really know how to tell my neighbor what you suggested. I appreciate it though, and I'm sure it will help me in the future. As I said, I'm no mechanic, just a high school kid with limited knowledge and a very busy life! I'll be sure to use advice from this forum more often, as everyone is very knowledgeable. Lately I haven't had any problems with my car *knock on wood* but when I do, I'll be sure to double check codes!

 

You put way too much faith in the "dealer". I'd say with certainty the the problem from the beginning was the faulty AIR pump fuse. If the EGR valve wasn't closing all the way the engine would have run poorly and it would have been stalling at idle.

What I don't understand is why you even asked for help, when you appear to have had no intention of paying any attention to it. Really inconsiderate of the people trying to help you.

Live and learn.

 

Yeah I guess I did. Didn't really think about it. Seeing as how my neighbor has always offered to help me in the past, I kind of thought after I posted that he might be offended that I was getting anonymous help and not fully trusting his advice. I didn't want to tell someone who has over 30 years of experience (including dirt track/high performance mechanic) in servicing vehicles that I was looking for another source of advice rather than his. I know everyone here has a lot too, but I'm personally close to him, and not just behind a screen. Didn't really think about that until after I posted.

You're absolutely correct though. Let this be a lesson to me! I'm truly sorry, and I'll definitely take the advice given on here the next time also. Some things said are like a foreign language to me, but I'm really here to look over things and get as much experience and knowledge as I can.

In the end, the car is fixed and running strong and hasn't thrown a code for about half of a year!

 

I appreciate your honesty. And I understand that you have no way to know how good the advice you are getting here may be. It's not all good. One way to aid your judgement might be as simple as looking at the number of posts, and the join date for the people who respond. I have lived with my 94 Formula since I bought it new in 1994. I've made a lot of changes over the years, most of the work done myself. And I have learned from my mistakes, and I really want to prevent anyone from making the same mistakes.

Good luck!

 

Thanks, and yes, your post count and knowledge and mostly passion for your car leads me to believe that you're a very good source to trust! At first when I got the car, I thought, "If anything fails, buy new, don't just fix the old part," because I wanted to keep it as nice as possible. Of course thinking about it, not everything needs to be brand new, and a simple inexpensive fix could have worked just as well. It was my first problem, and I figured to replace stuff would be best. In a way, it saves me from worrying about the replaced parts for a while, but being on a budget, some things only need a simple fix until new parts can really be afforded down the road. I really hope to keep my car for as long as possible, and anything I can do to keep it in the best shape possible, I will do.