Ignition interference in CB

Very good answers from Dart273. I used to run a CB repair shop before I got my ham ticket and ran into issues like this all the time. Like 273 said it's likely either ignition or alternator noise. Noise can be generated from several sources but those are the most likely. If it's alternator whine you can generally solve it by installing a filter you get at Radio Shack. If it's ignition make sure you use suppressor wires. And as stated not all CB's are created equal. A good receiver like a Cobra 142 has a much better noise blanker than a Cobra 19 (in fact the 19 has no noise blanker at all) or the illegal galaxy crap out there.

Also consider this: how good is your antenna? If it's one of those little 18" weenie antenna's cash it in for scrap. You'll get more for scrap than what it's worth. All antenna's will pull in noise but a good antenna will pull in the signal much stronger over riding the noise easier.