Hi,
When I look up the codes, I'm seeing different definitions. The P0334 is for a knock sensor and the 170 is for a fuel trim issue. Note that a rich fuel mixture can cause a backfiring issue.
Also, the knock sensor fine-tunes ignition timing. I don't think it could get far enough off to cause a backfire, but it certainly can cause valve ping.
Do you have a live data scanner? If you do, let me know what the short-term fuel trims are at idle. Take a look through this link as well.
https://www.2carpros.com/articles/engine-backfires-while-running
As far as the knock sensors, they are under the intake manifold. If you had dry brittle wires from the PCM, these could have the same problem because of location. The see a lot of heat.
If you look at the attachments below, I included the directions for removal and replacement. At least check the condition of the wires.
I'm really interested in knowing the fuel trims. You could have an intake leak, O2 sensor issue, fuel pressure issue, the canister purge valve could be stuck open, and so on.
Let me know.
Joe
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Tuesday, April 6th, 2021 AT 6:13 PM