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89 Cadillac Deville emissions failure


sleepy hollow's Avatar
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04-05-02, 09:30 AM   #1  
89 Cadillac Deville emissions failure

Here are the numbers:

Test--------Reading/[email protected]/[email protected]
HC ppm----------6/148----------------------------9/144
CO%-------------0/0.83--------------------------- 0/0.92
NO ppm-------2391/1110---------------------1836/1014
RPM---------------2083-----------------------------1544

167,500 miles, FWD, 4.5L, Auto transmisison

It failed the NO test (Virginia). My first inclination is replace the EGR valve since I understand this primarily controls NO by cooling the combustion chamber below 2500 degrees. Also, I think I still have the original EGR on the car.

In addition I guess the catalytic converter is likely OK since the other readings are fine and the failed readings are better at lower rpms. Finally, possibly O2 sensor? But that controls rich/lean mixture. I see no evidence of mix being too rich. Quite the opposite. Am I thinking straight?

Any other suggestions? Thanks.

 
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04-05-02, 09:49 AM   #2  
Joe_F
Yes, poor EGR function or clogging will cause high NOx. Also holes in the AIR injection system (or the inability of it to work right) will cause that.

So will timing and cooling system issues causing the car to run hot.

That being said, I thought VA didn't have emissions testing? My 1979 T/A was there from 1989 to 1991 and I don't recall any emissions testing at that time according to one of the prior owners I spoke with. My car was from Shenandoah Valley which I hear is beautiful country.

Nice older gent owned it who was a specialty Trans Am dealer. What a hellion! Lol.

 
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04-05-02, 10:11 AM   #3  
Yes, Virgnia, there are emissions tests...but on a county-by-county basis. I live in Fairfax County near DC. Need I say anymore?

As for your cooling and timing comments, I replaced the water pump, and timing chain about a year ago. I do not believe they are a problem, but I'll scour the service manual for those topics if the EGR replacement does not work.

thanks

 
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04-05-02, 10:14 AM   #4  
Billdo49er
Sounds very much like EGR may be your problem.Although a simple tune up may cure it.I also have an 89 Deville and take it through NJ insp.(enough said)I had a similar problem and tuned it up.(Including wires,fuel filter,pcv valve,and O2 sensor)
At one time O2 sensors were around $70(when i was a GM parts man back in 84) but now the are fairly inexpensive and should be replaced every 60,000 miles.Good Luck.

 
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04-05-02, 11:23 AM   #5  
Joe_F
Bill,

What dealers/places did you work in NJ? My sister is not far from where I live in NY and she is in Northern NJ up near Chester. Know where that is?

 
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04-05-02, 11:47 AM   #6  
Joe,

You mentioned northern Jersey and NY. I am from Westchester originally. Born in North Tarrytown (hence my user name).

Which suburbs do you live in?

 
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04-05-02, 11:51 AM   #7  
Billdo49er
I'm from South Jersey.We don't consider North Jersey as part of our stat.We consider it West NY.lol
I was a GM parts man at Prestige Pontiac,But then became a tech and moved around to several GM dealerships.(Whoever had a better deal.lol)Now they all want to hire young techs at less money so I started driving big rigs.
I have been turning a wrench now for about 30 years.

 
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04-05-02, 01:31 PM   #8  
Joe_F
I don't remember that dealer. I have bought out many of the dealer's old parts inventory around the country. I find things here and there for my cars and buy out whatever they have .

Didn't buy that one out. Lol.

As for your e-mail, the signature file saves me a lot of typing and redo. It refers people right to the information. I find I repetively answer the same questions when my signature file has a good amount of the answers to get people started .

Sorry, it's good to be extensive here. Lol.

 
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04-05-02, 01:37 PM   #9  
Billdo49er
Glad you didn't take the e-mail seriously.I wasn't sure whether you would or not.LOL

 
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04-05-02, 08:14 PM   #10  
knuckles
You might want to check the EGR passages in the intake manifold before you buy any parts. They sit directly beneath the throttle plates and are prone to clogging. You can usually open them up with a few pokes of a plastic tool (a ball point pen usually works quite well).

You can see & service the EGR passages by removing the air intake assembly from the throttle body and fully opening the throttle plates. Now would also be a good time to clean the bottom side of the throttle plates....they tend to get a buildup of solids from the EGR & PCV systems & can cause false TPS codes. Use Throttle Body Cleaner & a plastic bristled brush to clean the throttle plates & bores.

 
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04-08-02, 06:42 AM   #11  
Thank you for all of your suggestions. Just wanted to let you know that it was the EGR valve. I also cleaned the EGR passages which had quite a but of carbon buildup. It was indeed the original valve and it was pretty bad with crud.

Anyway, I had her reinspected and the NO readings dropped by 90% to about 230 from the earlier test.

I especially enjoyed the inspector's expression when he told me that since I had not spent the required minimum $460 with an approved and certified emissions repairman to repair or attempt repair after the first failed test, that he could not give me a waiver if the car failed on reinspection. I calmly told him that I understood the rules, but that I had repaired the car myself for about $50.

The shop was abuzz when the car finished the dyno test and 2 of the mechanics came out to present me with the results and ask me what I had done to the car.

Thanks again.

 
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04-08-02, 08:25 AM   #12  
Joe_F
Because a little work with the old noggin and TLC keeps them going for a long time.

Most cars can be brought into compliance with a little TLC and maintenance.

Good job. My hat goes off to everyone that contributed to the solution on this problem.

Score one for the forum

 
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