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Cadillac Repair/1991 Cadillac Seville no power and backfires

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Expert: - 8/4/2010


Question
QUESTION: Why would my 1991 Seville have no power, i replaced the fuel pump, fuel filter and tuned it up. had the converter removed because it was pulled. every time i check the codes the always different, the car drives but it has no power. i know these cars has power because i had an a different Seville that would just about burn its front tires off, this one i get run faster then it can move

ANSWER: Hello,

I don't understand if the conveter is on now or not.

Did it back fire before removing?

Generally, backfiring is caused by a valve or ignition timing. Running right it should burn the tires off! It is a very quick little car,

---------- FOLLOW-UP ----------

QUESTION: the converter is off and had less power with the converter on. I drove it for 1000 miles it started to gain power, the person i bought it from said it sat for at least 6 months. I also notice that one time check for codes i got two codes and then checked it again there was four codes pulled the negative cable and now theres two. I tried to clear the codes the way it say to your site and it wont clear them.

Answer
Hello,

The first problem is that a converter is required on this vehicle and that may be why you are getting the hard codes. You can do severe engine damage without the converter. I hope that did not happen.

The first thing you need to do is install a converter.
The computer system to operate in what is known  as a closed loop. Without the converter, the engine will definately not run righlt and you will set hard codes. The backfire could be attributed to this too. In the 70s we used to pull converters, but those cars were not computerized.

Since the computer, it is part of the total system. I am surprised whoevr made a pipe to bypass it would not have told you.

Now, once you get the converter back on, we can go over this. A mouse could have climbed up the exhaust while sitting for 6 months.

Bottom line- until you have the converter back on, I or anyone else is not going to be able to help you.

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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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