Posted to Technical Tips Forum on 7/6/2012

Ted,

Your little adventure reminds me of a similar experience I had a few months back on a rear-wheel drive Lincoln (about a 2001, sorry, don't remember exactly). It fell on its face on moderate acceleration seemingly at random; pulling over and slowing way down (not much choice there) caused it to perk back up again, until the next random event. After spending more time than I would have liked trying to nail it down, I finally caught the timing advance PID at zero during the event, and by chance noticed the traction control light on the dash at the same time! In my defense, it was a bright day, and the light doesn't have much contrast to begin with, but deactivating the traction control definitely nailed the source of the sag. When I got back to the shop, I got out, looked at the tires, and immediately slapped my forehead! The rears were a little bit smaller than the fronts, just enough to trigger TC under some conditions. Diagnosis complete!

Sincerely,

Michael Barry
Technician
Quick Stop Smog & More
Sacramento, California, USA