QuestionLately 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
AnswerHello,
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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