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1990 Cadillac Deville Car idles rough and has no power

Tiny
RECEIVER25
  • MEMBER
  • 1990 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 162,000 MILES
This car was running great on Monday and went to start it on Tuesday Morning and it ran real rough. No power to even get up a slight hill and rough idle.

Took it to auto repair and had them run a diagno on the car and they told me that the ECM was bad and that it was not sending power to several of the injectors and basically running on half the cylinders.

Went and bought New ECM and replaced, took prom card out of old unit and put in new unit. Cleared all the ECM and BCM codes from the system and started car, still have the same problem car runs like a junker no power.
Call the shop that diagonoised the problem and was told that the ECM had to be reset by someone with a scanner this is the only way. So after a very expensive part replacement still have to fix, car has new wires, spark plug, distributor cap, a rotor button. Any advance that might fix this problem would be greatly appreciated. I believe the Manual say that the EMC can be reset thru other mean, I do no believe the the first Ecm was bad, could the Prom card be the problem? I don't want to keep spending money on this car by guessing, and taking advise from a shop that I don't think they know what they are talking about.

Thanks
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Friday, May 22nd, 2009 AT 10:46 PM

13 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
If it ran fine then the next day it ran like crap, did you get gas? Test pump pressure and read any codes, read them this way and post results.
Cross these two terminals as shown, then turn the key on. Count the flashes, a 22 will flash as 2 flashes then a short pause, then 2 flashes, if more than one code is stored, the pause will be longer. The codes will display three times and end with 12. Write them down and post here. This connector is right under the middle of the dash...


https://www.2carpros.com/forum/automotive_pictures/62217_GM_DLC95_Older_21.jpg



https://www.2carpros.com/forum/automotive_pictures/62217_GM_Jumper_Key_3.jpg


Also check ALL fuses in car and under the hood.
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Saturday, May 23rd, 2009 AT 5:37 AM
Tiny
RECEIVER25
  • MEMBER
  • 11 POSTS
I ran a jumper wire as in diagram and the system give me nothing but the fuel level and trip usage, no flashes or 22.

The only code that come up are the one listed below:

E9.5
E00
E96
E01
E12
F00

I have ran a pressure check on the fuel it is reading 42 on prime start up and dropping to 38 while running. Thought maybe bad gas, so filled it up and no change. Shop told me that when they ran diagonistic that the Emc was bad, and that only communicating with half of the injectors. I am about ready to just give up and start looking for a different car. Any thing else thanks.
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Sunday, May 24th, 2009 AT 9:08 AM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Has it been verified that half the injectors don't have power? A couple things, first of all, there is no reset on the ECM, they are possibly talking about idle learn, this will not cause your symptoms. Try removing the oxygen sensor from the pipe, or disconnecting the exhaust before the cat. If it runs better and has power, you have an exhaust restriction. Is the distributor loose, causing the timing to be retarded?
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Sunday, May 24th, 2009 AT 12:11 PM
Tiny
RECEIVER25
  • MEMBER
  • 11 POSTS
I don't believe the car is retarded but more like the shop that told me the ECM is bad in the first place! This car has no cat it has been removed many years ago. I did some more testing on the car today, checking power to each injector, making sure the wire are right, all were working fine.

Then I did a pressure check on the fuel rack and got 41, and with the car running around 36. After shutting the car off and disconnecting the tester I notice that the test valve was leaking and when pushed in to relieve the pressure there was very little, this was a false reading.

So I removed the fuel filter believe that was a task, had to end up cutting it out, then put a hose on the line before the filter and turning the key on, the pump came on for about 1 second, and then shut off and stop pumping fuel, tried this several times and even turning the car over and the pump never engage during this time. I believe that there was never nothing bad with the EMC, and the shop stated the easiest thing first.

I do believe that the fuel pump should stay running as long as the key is on, due to no pressure limit switch on the gas system. I feel that the problem the whole time was the fuel pump is in the early stages of going out, and is no maintaining as steady pressure to all the injectors. I plan on going to the shop and asking for a refund, for services no rendered, shouldn't the fuel pump continue to run when not hooked up to the fuel system?
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Sunday, May 24th, 2009 AT 9:26 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
I sent you some new instructions for testing. Check email! Also when you turn the key to the on position, fuel pump only runs 2-3 seconds, a signal from the ignition system must be recieved so the pump stays on.
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Monday, May 25th, 2009 AT 6:56 AM
Tiny
RECEIVER25
  • MEMBER
  • 11 POSTS
Thanks for all the help, but car is still not right. I changed the ECM and no change to the running of the engine. I changed the wires, distributor, rotor button, fuel filter, and dropped the gas tank and removed the fuel pump and put it on the bench.

Run the fuel pump with gas in a pan and it run fine for a couple of seconds, and then the pressure reduced, notice that the strainer was clogged and not letting gas into the system, so replaced stainer and the pressure stayed the same, put everything back together and car started and engine ran smoother, but still did not resolve the problem. Car still seems to be running on half the cylinders. So after spending alot of money for a new ECM because that's what the shop told me, I am no closer to getting the car running any better. I feel the I might of got a faulty ECM.

What else could be causing this problem? I bad crank position sensor, this car is really taking it toll on my money and mind. Any suggestions would be greatly appreciated. Why am I not getting power to half the injectors. Need to check with NOID light tester. Any help removed one spark plug wire at a time and only acouple of them changed the running idle of the engine.
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Wednesday, June 17th, 2009 AT 7:26 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Have you checked the resistance of each injector? Best to do warm, if possible. The spec is 15-17 ohms. 90 was a bad year for injectors, they typically short out. On sevilles, they had potential of taking out the injector drivers in ECM, devilles not as much. There should be two harness connectors at the end of both banks, one will have eight wires, and one ten. Check the resistance at these connectors, it is nearly impossible to disconnect the rear bank of injectors individually. The connector with ten cavities, has the coolant temp sensor running through it, it is the yellow and black wires on one end. Each injector terminal is across from the other. If you have some bad ones, then you will need to disconnect to differentiate which is which. The noid light would be a good idea to make sure they all are firing.
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Wednesday, June 17th, 2009 AT 11:46 PM
Tiny
RECEIVER25
  • MEMBER
  • 11 POSTS
I disconnected the wiring harnesses going to both injector rails and checked each one with a omh meter and it seems that only acouple of them are even showing any resistance. Most are showing 0, and a few of the other are showing 3 or 4. They all can't be bad can they? Placed a noid light on each connector at the harness and they are getting power when the car is cranked over.

When the car is running it only seems to be running on half the injector, since I am not going that much resistance from the injectors what can I do to fix this problem, can I remove the injectors and clean them or do I have to replace them all. I don't see them all going bad at the same time. If they all have to be replace then, I will probably end up putting the car up for sale as junk or parts since injectors are just to expensive. Any thoughts?
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Sunday, June 21st, 2009 AT 1:46 PM
Tiny
MERLIN2021
  • MECHANIC
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If the readings are right then the cheapest way out is a set of good ones from a junkyard.
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Monday, June 22nd, 2009 AT 2:09 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
They probably have been going bad over time, and just not noticed. It is not a factor of being dirty, it is the coils windings shorting internally.
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Monday, June 22nd, 2009 AT 10:54 PM
Tiny
RECEIVER25
  • MEMBER
  • 11 POSTS
To get everyone up to date, I tested all the injectors for resistance and the meter that I was using must of had something wrong with it. The manual say that the resistance should be ranging from 11.4 to 12.3, only three of the injectors tested at 12, the rest 1, 3, 5, 2, and 4 tested from 1.6 to 3.

So I guess it was not the ECM after all, I removed the fuel rail yesterday, and went on-line and find a complete set for 165.00, re-manufactored. And they was so buy my old one for core price. Is there anyway that I might be able to clean these up and get them to working or do I have to replace them? I don't understand why so many of the injectors died at the same time.
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Thursday, June 25th, 2009 AT 7:10 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Its possible you just didnt notice as they deteriorated past the point of servicabitiy. No I dont think you will be able to rebuid an injector.
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Saturday, June 27th, 2009 AT 9:23 AM
Tiny
DENNISD131313
  • MEMBER
  • 1 POST
I have this car. It can get very TEMPER-mental. I always had idle problems until a customer came into my Napa store and told me about his 1974 Cadillac. It will only run good with Sonoco 93 Octane. So for the past 6 months that is the only gas I put in my car. Now my car runs like new in terms of idling. My though is that you got some really bad gas the night before and that it created havoc. I think I have problems with my computer maybe caused by my badly operating climate system throwing it off. My car at times has a sail on condition until the computer reboots. Then it goes back to normal driving. Hope that was helpful
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Monday, September 2nd, 2013 AT 7:49 AM

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