Oscar

My saga continues. Failed emission Test # 2 yesterday (nox again). Vacuum is getting to the EGR from the new soleniod. The technician hooked up ported vacuum directly to the EGR valve to see if it would make it stumble, which I believe it should cause some serious stumbling to the point of almost making the car shut off with that much vacumm. Upon doing that, the car showed no signs of even the slightest stumbling. The EGR is new, about 1 year old and has about 150 miles on it. The tech said that the EGR port in the intake could be blocked or the EGR could be defective. He also mention because I have a modified exhaust (1 1/34" SLP - dual cats - Flowmaster) I could have a lack of backpressure. I think the EGR is good but will verify this weekend when I take the Plenum and EGR off. The teck said I should check for blockage, stick a coat hanger, blow high pressure into it, reassemble and check again to see if the car stumbles. Does that sound correct? And what about the back pressure comment, is that a possiblity? I would hate to have to unmodify the exhaust. Is it possible to clean the intake with out having to remove it?

thanks

P.s. I also have new cats as of yesterday morning and new EGR solenoid.

sofakingdom

iTrader: (1)

Amazing sometimes how effective "low-tech" can be... just rod it out until you can blow into the holes and they flow freely.

Oscar

Thanks! Need I say that you are becoming my hero. I will try this Friday night and see what happens.

Is there any truth to the possiblity that my exhaust set up is causing a problem due to backpressure? I'm not really going to sleep well until I know I can keep my exhaust the way it is.

thanks again.

Sonix

iTrader: (1)

You can keep your exhaust, lack of backpressure won't do anything.

Oscar

That's reassuring...Is that a promise? I feel made blood pressure dropping...starting to see some zzzzz's tonight.

Sonix

iTrader: (1)

I guarantee it, or your money back Nah, I can't put my name on that promise, but your EGR is controlled by vacuum, exhaust is just what flows through it. The pressure from your exhaust system will determine how much flows through, but it won't make it work or not work.

Oscar

hmm...so is it possible that the EGR valve is opening and becuase there is not enough backpressure, the exhaust is not flowing throught the valve? And that's why my engine does not stumble at idel when there is ported vacuum directly to the EGR valve? Or does it sound to you like the port may be plugged and that's why the exhaust is not flowing? How big are those ports anyways that they can get plugged? If I don't have enough exhaust flow throught the EGR valve that mean a higher nox #....???

ploegi

No. Exhaust gas takes the easiest route. As the manifold is going to be lower pressure than the atmosphere, and the route to the intake is shorter.... EGR will still function normally. If it needs more, the computer will just extend the pulse width on the solenoid.

There are many many many folks running a free flowing exhaust, that do not have problems. You may just be running a bit rich, for that matter.

Oscar

I removed the plenum, checked the EGR valve. It is good, moved freely, holds vacuum. I took a coat hanger and shoved it as far as I could get it to go which is not very far. Then I blew air from my compressor into the two holes. Reassembled. Started the engine. I took ported vacuum directly to the EGR valve to see if I could get the engine to stumble. The engine continues to run strong with no signs of stumbling. I'm out of ideas as to why I cannot pass the NOX smog test...

From reading more material, could it be a defective Knock sensor? Carbon build up on the pistons and in combustion chamber? I just don't know anymore. Anybody care to take a guess? Why is my car not stumbling when direct vacuum is added to the EGR valve at idle for example???

Any help is appreciated.

NowTheBadNews

iTrader: (3)

TPI tends to plug it egr passages up right behind the throttle body inside the plenum. spray brake cleaner into all passages that will disintegrate any carbon build up where you cant see it.
carb cleaner also does good as well it will liquify the carbon buildup. pull your throttlebody off the plenum and you will see these passages. then spray cleaner in till you see it coming out the egr ports on the side of the plenum. find the small diameter tubes in the middle of the larger runners and spray cleaner in them. the remove egr valve and do the same there ... this will clear the egr passages. probably going to need 3-4 cans

Sonix

iTrader: (1)

Now if FI terminology is vastly different than carb, then what you say makes sense, but in the carb world, "ported" means vacuum only above idle, "full vacuum" is the opposite. Using ported vacuum should do nothing, if you're idling. Hook up your EGR to "manifold" (ie full vacuum), something that has vacuum on it at idle. (If you already are, then we're on the same page)....

Oscar

The vacuum is directly from a nipple at the plenum, hooked up to the EGR valve, so that it opens all the way and let the exhaust flow through at idle. Should'nt that make the car stumble as I keep reading?

Kevin91Z

iTrader: (1)

Tuned port cars have a normally open EGR solenoid, and the computer closes it except when its needed. Exhaust pressure has no affect on it. You're fine.

TBI cars have a normally closed solenoid and EGR valve and relay on exhaust pressure to open it. With a free flowing exhaust on a TBI car, they tend to set EGR code 32, as there is not enough pressure to open the valve and let the exhaust gasses in to reduce emissions.

Have you tried to run Seafoam thru the car yet? Also, how helpful is your smog tech? Will he let you play with the timing? You're allowed 3 degrees in each direction from the stock 6 degrees. Try running a pre-test at 3 degrees initial and at 9 degrees initial to see if that helps.

Lastly, stick a small piece of cardboard, about 12 inches by 12 inches in between the radiator and the AC condensor. That will block the fan and allow the engine to get a little warmer. A warmer engine will put out less emissions. Dont let it get over 230 degrees, though.

Oscar

Thanks for the reply Kevin. So if I understand this correctly, when the car is off, the EGR valve is closed and the EGR solenoid is open? The moment I turn the car on, the ECM closes the EGR solenoid, thus leaving the EGR valve closed because it is not needed?

I ran two cans of Seafoam and a bottle of G2P (the Guaranteed to Pass liquid) before the first smog ($65). Then I put in a new EGR solenoid (which I finally found) ($90.00) and went ahead had the both cats changed out with the Magnaflow ones ($400.00), and an oil change. $500 in and failed the second smog with close to the same NOX numbers as the first.
A Corvette/Muscle car shop which has been working on an engine quote for me refered me to a smog a CAP/Gold station that they work with. I went there and they did yet a third smog test ($55). The owner there is supposed to be a "Camaro" guy. I explained the history and what's been done to my car so far. They drove the car to get it hot then pulled it right into the shop. Did the test. This time, the car failed the 15 mph Nox by 1337-767=570 ppm but passed at 25 mph, 706-577=129 ppm. From there, I authorized an inspection ($90.00). This is where they put vacuum directly to the EGR to see if it would stumble and it didn't. I'm not certain at this point how valid that test is. The diagnosis was, EGR solenoid is good, now need to remove the plenum to check the EGR, and check for plugged ports. Other possiblities they said we're, possible undetectable vacuum leak and other things. Since the day ran out, I did that at home and saved myself $200. As decribed in one of my posts above, I stuck a coat hanger and compressed air but didn't see anything. So $700.00 plus later, still no resolution to my problem.

Kevin, I'm not sure how much latitude the Smog tech will give me but he was very helpful and was willing to do a manual mode test for me when I returned. I will call him tomorrow and see what he says about the timing and I will also put the cardboard in between as you say.

My Temporary Operating Permit runs out Feb 29th. At this point I want to throw an engine at my car. I wanted more power anyways and something that would assure me painless passing smog inspections for years to come. That is the reason for my post in the Engine Swap forum.

Sorry for the long post.

Thanks for the help and suggestions.

Kevin91Z

iTrader: (1)

If you've replaced the cats and run Seafoam thru the engine, then yes you have something seriously wrong. My guess would be the EGR valve itself if that hasnt been replaced yet.

jv9999

iTrader: (1)

It probably won't open at idle. Hook manifold vacuum to it, rev it up to a couple grand and then see if it will still idle (it shouldn't).

Oscar

Ok I did what you said, 3 degrees negative and the cardboard in front of the radiator. The previous smog station that was recommended) was to far, 35 min drive, that I didn't want to make since I was probably gonna fail anyways again. So I just went to the smog Shell station a few blocks from me. The guys there seemed to wanna work with me. The cardboard made my car run real hot (it was goin starting to go beyond 230), he had to shut if off a couple of times. When he finally ran it failed for the 4th time. He offered to do a diagnosis for another $75. Now I've spent over $800. He said he could fix it, he would take care of me. He went over the numbers with me and said my car was running lean. He said he could track the problem down and fix it. So $800 plus later I said no thanks, and told him I'm just gonna go have an engine rebuilt for me and be done with it. He said "what?", "I don't think you need and engine". I was frustrated and just wanted my baby back in perfect working order.

So I left and went to the shop to see the guys I had been talking to about the engine build (that is another story I'll post later in my thread in the Engine Swap forum you replied to). To make a long story short, they could do my engine but could not start for a few weeks which would take me past my Feb 29th Temporary Operating Permit extension. So I went home. On the way home, I couldn't help to think, I felt that the guy at the Shell station seemed so sure that he could find the problem and fix it. So I said what the hell and I stopped back in. I asked him point blank, you can find the problem and fix it? He said "yes". He said, here's the problem, pointing at the % CO2, %O2, and CO% numbers. He said, "the CO2 is too low, should be like a 14%. The O2% is too high. The CO% is too low, your car is running lean". He seemed so sure, I had already spent $800 plus, so what's another $100 or 2 right??? So I left it. 2 hrs later he calls saying, "it's done, it passed, it was your O2 sensor and it made a dramatic difference". Needless to say I just about fell over with happiness. I still couldn't believe it and I went to pick it up. I talked further to him with many questions. He explained that the O2 sensor was lazy, it was telling the ECM that the car was getting to much gas so the computer was making it run lean. The difference in NOx numbers was so "dramatic" that was an understatement (see for yourself) down below. And the numbers he said should have come up, came up. My car, seems to be running so clean now, I don't have to rush out and do the engine. I can instead take my time and do more research to get the ponies up. My latest smog #'s I guess are a real testament to how much I've taken care of my car.

So, $1K later, my car passed and all it really needed was a silly O2 sensor. What lesson did I learn? That I should learn more about how my car works so I can do most of the work myself. The thing that I have know all along however, is that most techs out there are just parts changers. And unless they have a computer telling them what part to replace, they are just guessing. The problem is, it is hard to tell those guys apart from the one's that do know what they are doing. Out of the 5 guys that smoged my car including the “Camaro Guy”, only one used the other numbers as an indicator of the problem was, found it and fixed it.

Thanks Kevin for trying to help me and all the other guys that tried too. I know it’s hard to diagnose with out seeing the car. The other guys have no exuse!

five7kid

iTrader: (14)

NOx is formed under high pressure and high temperature conditions. The EGR valve puts a little exhaust into the air/fuel mixture to lower the combustion temp.

Guess what running lean does to the combustion temp?

Note to future posters: Include all your numbers, not just the one you're failing.

BluFBdy

iTrader: (1)

Its the simple things that screw it up, and as for the techs i will agree most of us are parts changers only because they havent been taught jack on diagnosis, if you cant properly diagnose the problem and isolate it all you will do is change parts until the problem is fixed say oh...about $1000 later. I'm suprised the O2 sensor wasn't one of the first things you changed because when you fail smog dont they give you that little pamphlet that says you probably failed because : X, Y, Z, change these and you MIGHT fix it? Plus when i failed the smog guys told me, check my EGR and my O2 sensor first and go from there. Some techs just need to find a different profession, like a desk job because they make the rest of us look bad

Oscar

I didn't get a pamphlet. I did chase the EGR all over the place. Replaced the solenoid too. But not one of the techs mentioned running lean becuase of this or that. One thing is clear, some of the smog techs are trained to operate the smog inspection equipment but cannot interpret the results. Nor does it look like they have any idea what good numbers are supposed to look like. Seems like if I wanted to, I could be a trained to be a part time smog tech....
Then I can keep my full time job at my desk.

BluFBdy

iTrader: (1)

ha ha yeah, you can train any moneky to be a smog tech and say pass or fail, its the ones that say, hey you probably failed because of this, and are actually telling the truth not spewing BS, to be honest on average, 1/4 of the people at my voactional school become AZ smog techs, and its noramlly the 1/4 that dont pay attention for the important things, like diagnosis and isolation lol.......maybe theres a connection

84redta

iTrader: (34)

well now you know where to take your car at least These situations are actually kind of good. Now you know you can just go down the road and talk with someone actually knowledgable. good to hear your legally back on the road!

Kevin91Z

iTrader: (1)

Congratulations Oscar, that is awesome news! I'm glad it is finally fixed. Will we see you and your car at the SoCal February meeting?

Oscar

I would love to try to make it. Can I get the date and time? I'll look in the So Cal forum too to see if it's posted there somewhere.

Thanks again everyone!

Oscar

Nevermind, got the location and date at the SoCal forum. Hope to see you there!

Oscar.