eHam Forums => Mobile Ham => Topic started by: KB9WQJ on June 23, 2004, 11:09:50 AM

Title: Onboard computer problems?
Post by: KB9WQJ on June 23, 2004, 11:09:50 AM
Hello all,
Is it possible to permanently damage your onboard engine control computer with ham radio (incl. HF) equipment?  I don't mean RF getting in while you are transmitting, I mean causing the engine to run poorly and the Service Engine light to come on long afterwards even if the radio is turned off.  I ask because I recently had the engine light triggered by a DPFE sensor and some problems with the plugs and coils over plgs fixed (ie. replaced). When I got the vehicle back, a few hours later, then Service light cam back on and the engine was running rough again.  I took it back and said it wasn't fixed but I want to be sure I am not the problem.  Is it possible that a poor battery could cause such symptoms?
Thanks in advance.

Title: Onboard computer problems?
Post by: K0BG on June 23, 2004, 03:08:20 PM
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.

Alan, KØBG

Title: Onboard computer problems?
Post by: KB9WQJ on June 23, 2004, 03:59:55 PM
Thanks Alan.  Your info is reassuring.  I do have the power directly to the battery.  I have since spoken to the service guy and we have traced it to EGR valve stuff.  It appears the original sensor wasn't the problem, it's just that Ford has had so many go south that they suspect and replace them by default, then see if there's more going on afterwards.