Cb radio install issue

Man I've nearly hit a wall on this one..
I still have two radios in the truck old and new. I was removing a old power filter from the truck to see what did work some time ago. It consisted of a small toroid and two small capacitors the toroid only filtered the positive lead and the negative lead was only had a small amount of capacitance added nothing to really filter ac out. During the noise filter demolition, I accidentally ungrounded the old radios power lead, but still had a extra ground ran the the radio chassis from time ago. If I unhook the coax, feed positive into red power lead, float ground power lead and ground the radio chassis, I'll have no engine noise. Normally I'd have engine noise powering with the power leads without coax. So I've made some progress. Now here is where it flips on me. On my new radio still hooked up through the power leads, doing its first radio check since adding the 7 ground straps. I'm now detecting the transmission of engine noise over cb to other radios for the first time, as always engine noise on my end too. With the old radio powered up and antenna attached, with it's experimental power arrangements. I get lower engine noise from coax connected.
So here's my next test ill try, i'll remove all ground straps added from between my last two different cb comunications test, retest my old cb with the chassis ground only method, on it unstrapped. If it works I'll reverse engineer the alternative filtering being done in the old cobra radio, with my powering method and see if I can duplicate it into my newer cobra 29lx bt. I'm suspecting the cb radio case is fed to a toroid, then fed into ground I haven't cracked it open yet.
Alternatively powered engine off and coax connected I can say the range seemed unhindered by my alternative wiring.