EGR is on your intake manifold, you can usually see 1 vacuum line going to it then a rubber diaphram inside , looks like a small flying saucer. Dont know if that will cause your backfire though , i would guess no. Backfireing is when you have unburned fuel going into your exhaust , and the heat inside there causes it to ignite. EGR just recycles exhaust gasses back into your Carb / Injectors
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