I don't have a Petteroid, but I can offer some insight into VO conversions in general.
Hi again, is anyone running a petteroid on veg oil?
In the early days of VO conversions, direct injection engines had significant problems with ring coking because the VO was not being heated enough, or the oil was injected while the engine was still cool. Indirect Injection engines were more successful because the ignition chamber in the head made it harder for the unburned oil to work its way into the rings.
The current thought regarding VO in direct injection engines is that as long as the VO is heated sufficiently and is injected into a hot engine, you won't have problems. If you inject cold (less than 160ºF) VO or your engine is not up to temperature the oil will end up in the rings and eventually lead to coking.
The trend in VO conversions on DI engines is to use heaters on the injector lines to heat the oil to between 200º to 250º. At this temperature, the viscosity of VO is nearly the same as diesel.
How hard are they to start on veg oil?
I have started my Changfa on cold VO (~70ºF) and it is something I don't want to do twice. I cranked for about 30 seconds before I started getting any form of firing. Eventually it started popping, with lots of white smoke, but not enough to keep running. I kept cranking for another 10 or 20 seconds before it finally started to run.
Once the VO and engine are up to temperature, I can shut down on VO and restart within a minute or two without any problems. It starts up just like it does on diesel.
Trying to start a cold engine on VO is asking for trouble because all of that cranking is pouring cold oil into the cylinder which will get into the rings and turn to carbon. (There are people who do it all the time, but I'm not aware of anybody with a direct injection engine doing so).
The real answer to how hard is it to start on veg oil is "you don't start on veg oil". Start on diesel. Once the engine is up to temperature, and your VO is hot, the switch to VO is totally seamless. The only clue you have that you are running on VO is the exhaust does not stink as badly.