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1996 Deville 4.6
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51 Posts
Discussion Starter #1
I have had a problem with my 90 Deville, 4.5L fwd. In the morning, it starts up with no problem and runs fine. After it heats up and warm air is coming from the heater, it starts to run like crap and cant really be driven. I checked most everything and got frustrated and took it into the shop. The guy at the shop checked the ecm said it was good but that when the engine reached operating temperature, 5 fuel injectors started dumping gas into the engine, causing the problem with driveability. He says replacing the injectors will solve the problem. My question is, Has anyone heard of this problem? It would seem to me that if the injectors fire correctly when its cold, then the problem would be with the signals the injectors are getting after the engine heats up. The shop has said that if it doesnt fix the problem, I wont have to pay for them, so at least thats good. I have heard of strange things with this car. A few years ago, I was having a driveability problem that turned out to be a bad ground from the atlernator. Any feedback would be appreciated. Thanks
 

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1995 Sedan De Ville (4.9 L)
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581 Posts
I would agree with you that injectors are fine in your case. But how did the shop figured out that 5 injectors went crazy when the car got in the closed loop??? Is it possible?

Well, if the control is acting funny as you suspect, you might try to un-plug either O2-sensor(s) or coolant temperature sensor to force your car to be in the open loop. If this solves the problem, it may be an ECM related problem. If not, maybe when injectors get warm, they just don't work properly... Well, this is just my guess.

Good luck.
 

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70 Fleetwood, 87 and 90 Brougham, 94 Fleetwood
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215 Posts
I realize that injectors on these engines can be problematic, but for 5 to all of a sudden go bad when the engine goes into closed loop is a bit odd. Maybe whhile doing an injector balance test they found 5 that are bad, but I wonder if they are bad enough to cause your problem.

You may have an O2 sensor going south. Also, I would check the parameters of the coolant temp and manifold air temp sensors.

Mike
 

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1995 FWB 124,*** miles
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2,212 Posts
What if your ECM just warms up by the heater core (which is in close proximity)? Remove the glove box and tap on ECM when it acts up to see if it makes difference.
 

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1996 Deville 4.6
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51 Posts
Discussion Starter #6
Well, the car is still in the same shop! It wasnt the fuel injectors nor the FPR. The mechanic brought in what he said was a specialist with his diagnostic equipment and diagnosed a defective "pick up coil" on the distributor. The mechanic said he had checked that before and his equipment said it was ok. He is replacing this pick up coil. I had just replaced the whole distributor not more than 1 yr ago so I am somewhat suspect as to this diagnosis. As I said what this car does is starts up fine when cold, runs great for awhile, then starts surging and running so bad it cant be driven when it heats up. It is not overheating though.
Will a defective pick up coil cause this problem? Should this part go bad so fast? and what does it cost to get a new one? Thanks for all of your help
 

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1995 Sedan De Ville (4.9 L)
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581 Posts
Well, now it makes more sense.

I had the similar problem before. It turned out to be a bad something in the distributor. I didn't have right tools to replace things inside the distributor, so I am not sure what went wrong...

Anyway, it is very possible a pick-up coil acts funny when heated.

When the whole distributor was replaced not too long ago, was it a reman., brand new ACDelco, or what? I have heard some reman.s may not have all new parts in it. Sometimes (I assume depending on reman. factory), if parts are checked out OK, they will keep using the same old things and replace ONLY failed parts. Or some non-OEM parts in general may not handle heat and other conditions as good as an OEM part. Well, if non-OEM cheap parts were installed in the distributor, I would guess that it has higher probability to fail quicker. Could be less than one year. But this is just my guess.

I guess you just don't want to replace things that is fine (I am that way, too!). From this point, you may want to get a distributor at some junkyard and just put it in. If this solves the problem, you know what you have is bad. So, what I said above was right. Then you can drive your car until the junkyard distributor dies. If this does not fix the problem, apparently your instinct was right that your mechanic may not know enough. So, you can go some better place and avoid paying money to someone who doesn't know what he is doing.

Good luck!
 
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