Joe,
I see Dave's comment, which I am sure is 100%. Having already checked this out beforehand, I decided to post just in case.
The BOAC 787 has this in the aircraft.cfg:
[EFFECTS]
wake=fx_wake
water=fx_spray
dirt=fx_tchdrt
concrete=fx_sparks
touchdown=fx_tchdwn, 1
How does yours read?
EDIT: Having read what Dave said, here's the same section for the loverly Mosquito:
[EFFECTS]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn_m, 1
Checked the Aerocommander, which is different again, touchdown = fx_tchdwn_s, 1
I've just looked a bit deeper and see that "m" and "s" stand for medium and small smoke.
There is a you tube video here talking about changing files:
https://www.youtube.com/watch?v=QbM9jvplzw4
Sadly, this may not help you on take off.
However, there's a discussion on Flightsim.com, see here:
http://www.flightsim.com/vbfs/showthrea ... s-smoking-!!!
So if you have any snow on account of your current season in the US of A, that may be your solution.
![Dunno :dunno:](./images/smilies/102.gif)