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Cadillac Repair/1990 Cadillac Coupe Deville

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Expert: - 2/11/2012


Question
Lately my 1990 Cadillac Coupe Deville has been having problems, Its spews black smoke with a rich gas sent, it doesn't want to kick over when I try to start it, It turns off while I'm driving, The gas indicator is all over the place, and it chokes harshly in the afternoon but not in the morning. I've replaced the spark plugs and their wires, the starter, the O2 sensor, and the gas filter

Answer
Hello,

O2 sensor and plugs are after affect damage for dumping out all the unburned gas and not the cause of your problem and running like this could plug catalytic converter as well.

Well, the very first thing I would o is check for computer diagnostic codes. I hate to tell you, but none of the parts you change except for the wires would not have needed to be changed, except for the damage you are doing with the engine running like that. You might en up putting new plugs an O2 sensor and a cat in it if you continue to run like that.

This computer system is not high tech and to check the codes we wold place a wire across the terminals on the diagnostic port below the steering column on Oldsmobiles, and I believe Caddys are a little different.

I bet if you looked on the Internet for computer diagnostic testing for a 1990 Caddy, you would find the simple procedure.

What you are looking for is a code stored in the computer to give you an idea as to what the problem is.

This is the first place I would be looking. A code will flash. Code 13 is a O2 sensor. Code 34 would be a map sensor.

If you are trying to fix this yourself, I would also recommend trying to buy a factory service manual from Ebay or Craigs and follow the flow charts. This way you are not wasting money changing parts.

Good luck.

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Rob Painter

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Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

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Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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