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Discussion Starter #1
I have a frustrating problem I hope one of you can help me with. We have two 1993 Sedan de Villes which we love, but we have a problem with one of them. Sometimes it will shut off while driving, usually while decelerating. The car runs great, has great pickup, great power. But every once in awhile, for no apparent reason, it will simply shut off while driving. Sometimes it will drive fine for two or three weeks, then shut off twice in one day without warning. My daughter primarily drives this car and it is a very scary situation because of course she loses power steering and brakes, and since it usually occurs when she is coasting to a light or slowing down on a curve, she has to react quickly by throwing it into neutral and restarting it (which it easily does every time). The problem is that we have had the car in the shop several times, but the mechanics can't figure out what is wrong with it. They (and three other shops, including the Cadillac dealership) essentially have told us that they cannot reproduce the problem, and until they can, they basically don't know what to fix. We finally just had the shop replace the EGR valve because we had read that this can cause stalling on deceleration, basically just a shot in the dark. My daughter loves this car and can't bear to think of giving it up, but this is very frustrating. The car has 160K miles on it and otherwise runs great. Help!!
 

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seems like it stalls when it needs to idle...

my 4.9 did... or used to do that too... she hates idling in stop and go traffic.

be thankful you can throw it in neutral and restart, my PRNDL switch is 1/2 broke, and the engine will not start in neutral, I gotta come to a comeplete stop, put it in park, and restart... although a couple times I did it quick without thinking and put her in park going about 5mph :shhh:

Really though, I think if you rod out the EGR tubes, that is a start, do a search, but basically you remove the air intake, open the butterfly valve in the throttble body, and using a metal hanging unbent, just rod it all out to get the gunk borken up.

Replace the PCV valve, $3, and that could cause idle problems. Have you done a recent tune up (plugs/wires, cap&rotor etc...)? if not, do that. When i changed to the Ford injectors, that helped.

Let us know how it works... loosing the engine really isn't all that bad, if you are moving, the steering isn't too bad, and you have 3 pumps of the brakes before you loose the power assist.
 

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I have a 1991 Deville that does the same thing when coasting to a stop. I am still looking for some direction also. Will keep you advised if I find my problem.
 

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Night Wolf is correct. It is a common issue with the 4.9... Clean out the EGR tubes in the trottle body and that should do the trick. I was able to accomplish mine with a .22 or .38 gin barrel cleaning kit and carb/throttle cleaner. Do a search for EGR tubes and you should see numerous threads on the details of cleaning the tubes.
 

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Discussion Starter #5
Thanks for the info on the EGR tubes. Are they difficult to clean for someone who really doesn't know a whole lot about car repair? We just had the EGR valve replaced - would they have cleaned out the tubes in the process of the replacement? Thanks again for your info!
 

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nah, the egr tubes are seperate. They are the two tubes that you see looking up at when you open the butterfly blades of the throttle body. Unscrew the aircleaner from atop of the enginge. underneath you will see the throttle body and a pair of butterfly blades. push them open and use a flashlight to look down inside. you will see two hollow tube a little larger than drinking straws looking up at you. they are most likely filled with black carbon deposits. They need to be cleaned out a pipe cleaner and carb cleaner. I personally found that a gun cleaning kit, I bought for $10 at Dick's Sporting goods, worked very well. It was firm enough to go all of the way down. Use the search tab at the top pf this website and search "EGR TUBES" and youwill find numerous threads with the direction on cleaning these tubes.

Good Luck
 

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Discussion Starter #7
Thanks so much for all of the advice. Sounds like we may have talked them into replacing the EGR valve for nothing. I will try to clean out those EGR tubes and let ya'll know how it goes. Thanks again for all of your advice.
 
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