Contrary to popular opiinion, all EECs are well shielded. Not to protect them from amateur RFI, but to meet FCC part 15 rules. This does't make them idiot proof, but almost.
The possiblity of RFI is why it is highly recommended to wire the power directly to the battery and not use vehicle wiring. I have installed radios in quite a few cars, and I have never had a problem with a EEC, CPU, or any other control due to RFI. Except....
An Icom 706 has a lower voltage limit of about 11.6VDC. Any lower and the radio shuts down. A similar things happens with some on-board devices. My ATC (auto traction) light will come on and stay on when the voltage drops below 11.8 or so. Other than the light, no permanent damage has occurred. I have an idle stability problem for the same reason, so I limit my transmissions while stopped at a stoplight, or dimply turn off the amp.
The only reported BAD thing I can remember reading about dealt with setting off an airbag on an early Ford police car. Ford's recommended fix was to always connect the power directly to the battery. Nuf said.