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Failed Emissions..


DashingDaryl

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I failed emissions with my 95 Deville (Non Concourse) The flyer the emissions guy handed me explained it was most likely an EGR problem or a Timing issue. Since our cars are timed by the ECU, I am assuming it's an EGR issue.

The weird thing is my car doesn't show any codes when I check the on board computer. Every thing reads fine.

The car knocks when I accelerate. It also isn't doing so hot on Gas Mileage.

Does that sound like an egr problem to you, or could there really be a timing issue? I replaced my ISC and that thing you have to calibrate with a Volt-meter but other than the knocking, the failing and the gas guzzling, things seem to be ok..

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2 questions...

What part of the test failed? HC or what?

and...

What type of test is it? Is a simple stick the wand in the exhaust idle test?

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If you're observing audible part-throttle detonation, it is almost certain that the car will fail due to excessive NOx levels. Search the archives for information on EGR tube cleaning. You could simply retard the ignition timing to make it pass, however, fixing the problem would likely improve your fuel mileage.

___________________________________________________

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Rod out the EGR tubes under the throttle plate and that should fix both the emissions problem and will improve the fuel economy.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I failed emissions with my 95 Deville (Non Concourse) The flyer the emissions guy handed me explained it was most likely an EGR problem or a Timing issue. Since our cars are timed by the ECU, I am assuming it's an EGR issue.

The weird thing is my car doesn't show any codes when I check the on board computer. Every thing reads fine.

The car knocks when I accelerate. It also isn't doing so hot on Gas Mileage.

Does that sound like an egr problem to you, or could there really be a timing issue? I replaced my ISC and that thing you have to calibrate with a Volt-meter but other than the knocking, the failing and the gas guzzling, things seem to be ok..

Explain what you mean by gas guzzling? If you are gas guzzling its possible that you have a bad fpr or injectors. My 4.9 got good gas mileage.

The 95 has a 4.9 that had a number one main bearing knock that is benign adding a single quart or two of 10W40 to the 10W30 when you change the oil may lessen it. If you are using synthetic, synthetic oil tends to accentuate the knock.

Please give more details on the knocking when it occurs, it maybe be detonation as mentioned above. The only way I got the detonation to stop was to clean the hell out of the EGR tubes and to replace the EGR with an OEM unit (not aftermarket). I also had a bad CAT but you would know that from the rattling that it makes when it is bad.

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It is indeed excessive NOX; they determined that when they put the hose to the end of the exhaust and drove the car at varying speeds, up to 60 miles an hour.

The Limit was 2.0 and the car was putting out 2.6

I get one retest free. The next test is $27.50.

I can get a EGR valve at the dealer for about $60 (After my a discount from a friend who works there)

Would you risk just cleaning the egr pipes and taking it for the retest, or would you go ahead and buy a new egr and clean the pipes?

Should some kind of Code been set?

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How is your idle. You did not explain when you are getting the knocking you described. It it a noise that you sometimes describe as PRE-ignition but is in actually detonation. Detonation will occur as you are driving down the street at an average speed no matter if you are accelerating or not. If it is detonation and not knocking I would replace the EGR myself but thats me. My engine ran so much better when I replaced the EGR, it is near impossible to clean them. How many miles. You could just clean the tubes and attempt to clean the EGR, by taking it off and basically tapping on it and moving the pindle, but I would not want to cost you $27.50 if you fail. The price you are getting from your friend is good.

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I can get a EGR valve at the dealer for about $60 (After my a discount from a friend who works there)

Would you risk just cleaning the egr pipes and taking it for the retest, or would you go ahead and buy a new egr and clean the pipes?

Hell-ooo Maybe you're not listening. I think the recomendation was to clean the tubes and EGR passages (mouse holes I think they're called)...NOT to replace your EGR valve. I thnk that if it were an EGR valve going bad then a code would have been set. Just clean the tubes.

Now for $60.00, your not gonna get hurt too badly, I'll grant you that. But I don't think it will be needed.

Never underestimate the amount of a persons greed.

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I can get a EGR valve at the dealer for about $60 (After my a discount from a friend who works there)

Would you risk just cleaning the egr pipes and taking it for the retest, or would you go ahead and buy a new egr and clean the pipes?

Hell-ooo Maybe you're not listening. I think the recomendation was to clean the tubes and EGR passages (mouse holes I think they're called)...NOT to replace your EGR valve. I thnk that if it were an EGR valve going bad then a code would have been set. Just clean the tubes.

Now for $60.00, your not gonna get hurt too badly, I'll grant you that. But I don't think it will be needed.

JohnnyG, I think you are talking about a 4.6 Northstar, correct? I believe he has a 4.9. No mouse holes and a vacuum operated EGR if I am not mistaken.

I would check the EGR. Put you finger under it and you should feel the diaphram. Rev the engine and you should feel it move. If it does, the EGR is working. Just rod out those tubes in the throttle body.

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... I would check the EGR. Put you finger under it and you should feel the diaphram. Rev the engine and you should feel it move. If it does, the EGR is working. Just rod out those tubes in the throttle body.

Another quick EGR valve system check. There should be no exhaust gas added to the intake at idle.

If you lift up on the EGR valve diaphram at idle, the engine should stumble just a little which tells you the EGR valve WAS closed (as it should be).

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Thank you all for your help, especially Bbobynsky..

UNFORTUNATLEY it didn't work. The car has about 68K miles on it, and the tubes were clogged but not that bad. One was clogged about 30% and one was clogged about 60% I cleaned them out anyways. One of the vaccum elbows broke in my hand when I was checking the hoses, so I replaced it with one from autozone.

I noticed the car still knocks when I drive it slow.

As much as I tried, I could not get the egr valve to act any differently when I put my hand under it. It always felt the same when I increased throttle with my hand.

I put power to the EGR Solenoid, and expected to hear it click, but I got nothing. I reversed polarity and still got nothing. Should I hear, or feel some kind of click?

I also noticed the throttle body gasket was all dried up and cracked, would that make any difference?

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Wearing light gloves as the area gets hot, try pressing up on the EGR diaphram while the engine is idling and see if it stumples or stalls, report back. JimD suggested this above I am curious if it stumbles. You can buy a handheld manual vacuum pump from sears to check the diaphram also, or put a clean hose on it and try sucking to see if the diaphram moves, if not the vacuum 'motor' may be shot. It could be stuck also, and pushing up on it may free it. I will look into the solenoid for you in my manual later. When I cleaned my tubes I took off the EGR and used top engine cleaner and round gun cleaning brushes and blew them out with compressed air with a rag over the EGR port (where the EGR came off). Then replace the EGR with a new gasket. Mike

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Sounds like a bad EGR solenoid. Try testing the EGR valve by hooking it directly up to vacuum while the car is idling. If it is good, the engine will die. You can test the EGR solenoid by removing it and hooking power directly up to it. If it is bad, you won't hear anything and it will not allow any air to pass through it.

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Thank you all for your help, especially Bbobynsky..

UNFORTUNATLEY it didn't work. The car has about 68K miles on it, and the tubes were clogged but not that bad. One was clogged about 30% and one was clogged about 60% I cleaned them out anyways. One of the vaccum elbows broke in my hand when I was checking the hoses, so I replaced it with one from autozone.

I noticed the car still knocks when I drive it slow.

As much as I tried, I could not get the egr valve to act any differently when I put my hand under it. It always felt the same when I increased throttle with my hand.

I put power to the EGR Solenoid, and expected to hear it click, but I got nothing. I reversed polarity and still got nothing. Should I hear, or feel some kind of click?

I also noticed the throttle body gasket was all dried up and cracked, would that make any difference?

I don't think the PCM will allow any EGR flow while the car is in park. Have a helper place the car in drive and lightly crowd the throttle with the brakes applied. You should then feel the EGR valve move.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hey thanks, that is a good thing to know.. (The egr doesn't flex in park)

After I replaced the solenoid, I took it for a spin, and I had a worse knock then before. Not knowing that the PCM wouldn't let the EGR flex, and mad the egr wasn't moving, I took it to my friend who hooked a hose to the egr and tried to blow through it. He said that if you can blow through it, then it is bad. He could blow through it, so I went and bought a new EGR from the dealer.

I thought it was odd that both my solenoid and egr would go bad at the same time, but I guess it's possible. It would seem that if you can blow through it, the diaphram is open, and that would let the vapors into the engine, which would eliminate the knock. (But what do I know) I have not put the egr in yet, but will tonight and post back tomorrow.

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Blowing through it only shows that the diaphram is blown, it will not allow air in the engine as the diaphram/vacuum motor only pulls up the pindle (sort of a valve) that opens to allow exhaust to circulate. The diaphram is separated from exhaust gases. It sounds like you found the problem the EGR as I noted earlier (that I was nicely slapped down for suggesting to replace :lol: ). It is odd that your egr solenoid was bad also. Terrific, your knock should have stopped now that exhaust is circulating and you will probably get better gas mileage...good luck with the inspection.

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Thanks to all for their help and suggestions..

For the folks who said I just needed to clean out the Tubes, I say thanks and that you were right (partly) the tubes had a bunch of carbon buildup, but that wasn't the problem entirely.

For those who suggested I replace the EGR solenoid, I say thank you, and say "You were right, it was broken," but not the problem solver.

For those who said I should replace the egr valve because it was not that expensive in relation to the Retest, I say thank you. That helped a lot, but it still wasn't exactly the problem.

For those of you who took the random guess that a field mouse would take the insulation off the hood and shove it into the EGR valve, CONGRATULATIONS, YOU FOUND THE PROBLEM!

When I took off the egr for the replacement, I found an square inch of hood insulation shoved into the port the egr goes in. I don't know if it got shoved through the egr, or if it was shoved in somewhere else, and just ended up in the egr. Eithe way it was blocking the passage way and causing my problem.

It kind of made me mad because now I have a new EGR, but I guess it can't hurt the car.

Replacing the EGR was kind of a pain. I had to remove the throttle body, and the thermostat housing to get to the two bolts, but at least the car should pass emissions now.

Thanks again!

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