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Cadillac Repair/84 coupe deville black smoke

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Expert: - 1/27/2009


Question
I have an 84 deville w/ the 4100 engine. sometimes the service engine light comes on and the car suddenly blows black smoke and runs terrible. this problem is preventing me from driving it due to emission testing. when the light isnt on the car runs fine. any advice? is it a sensor?
thanks a lot
don

Answer
Hi Dan,

I can't help you a lot on this issue because I am really straining my memory. 25 years ago and all. The reason the light comes on is because it is out of the loop and that is why it is running bad at that time.
Anything could be a problem however, you have an advantage here.
The service engine light will store a code.
I would tell you how to take a paper clip and put it on the terminals at the obdI port under the dash, to flash the codes, but it is too many years since I did this.

Go down to your local auto parts store. Tell them you need the tool to flash or identify the trouble codes. These tools are pretty cheap now.

Hopefully, the tool you get will identify the codes and what they mean. For example: code 13 would flash on the dash engine light, a long flash and three short flashes. If you looked the code up, you would find that it means a bad O2 sensor.

The tool you buy should identify the codes. If not go to a library and see if you can get a 1984 Cadillac service manual for emmisions.

Sorry I could not be of more help, but hopefully I pointed you in the right direction.

I have an 83' Eldo with the 4.1. I love the car!!!

Good luck!

Rob

Cadillac Repair

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Rob Painter

Expertise

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?

Experience

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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