Q: Spark knock

asked by on August 18, 2016

I just had my cats deleted. When I tried opening it up a little while I was driving home it didn't seem to be getting any power and while accelerating I can hear a knock. When I deleted the cats did I cause the spark knock, how do I make sure it's a spark knock, could it have been there before and I just didn't hear it, and what do I need to adjust to get everything running right now that I deleted the cats?also if it wasn't caused by deleting the cats what should I look for, how much engine performance is lost due to spark knock? Thank you for your time.

My car has 190000 miles.
My car has an automatic transmission.

If you are getting spark knock then you may have a bad mass airflow sensor telling the computer you are at or above 10,000 feet above sea level and would run the engine lean. Have the sensor tested. As far as deleting the catalyst I cannot comment since it would be against the law for me too. However if you were putting in a test pipe for testing only then you would need to somehow bypass the O2 sensors. If you’d like to get some help with this, consider YourMechanic, as a certified technician can help diagnose the noise you’re hearing firsthand.

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