Question1987 Cadillac Sedan In park step on it and it is good backfires at high RPM. When you drive and ease into it it acts like it has no power. Have replaced the rotor, coil and cap. Could it be the catalytic converter collapsing?
AnswerHello,
The problem could be numerous things, but your description of the symptoms could be consistent with a plugged catalytic converter.
To isolate the problem, what we used to do is disconnect the exhaust system at the manilfold. If you do so and donut gaskets are required, make sure you buy them before you partake on this adventure. If you don't use them, you should be able to return if you don't need them.
Test drive the car making sure you have the exhaust tied up good with steel wire. Careful, the engine will be noisy, but if the cat is bad, you will notice an instant difference on acceleration with no acceleration problems. Then if that was the problem, go to an exhaust store like Midas, Merlin or Carex and have the converter changed.
Another way that might show up for you that may be a little easier is drive the car at night. Park the car, let the engine run and look under the car at the cat. If it is cherry red, you know the cat is bad.
I do not recommend driving the car a lot if this is the problem, because under the right conditions, an overheated cat can cause the jute and the carpeting to smoke and start the car on fire. This is an extreme scenario, but it can happen.
Good Luck!
Rob
