Had my PFC installed few days ago. Did the idle learning process and a short rideout-everything worked fine! Next day I did again a rideout again everything alright. Yesterday I did a big rideout (about 500km) and at each stop after starting the engine something was weird. First one was at the petrol station-I only shut down the car for about a minute and when I restarted it the engin keept reving to about 3500 or 4000rpm-I heard this should be normal due to a short stop and something with the waterpump...whatever it normalized after a minute. Next stop was for lunch, after about 300km. Before I restarted the engine I let the fan run-as watertemperature was high (117 degrees!) down to 93. Started the engine and the revs felt down to almost 500rpm and probably would have died when I would not have had keept at 1000rpm for about one minute again-then it turned to normal again. I though that could have been due to the high temperature and that I had the aircon on when starting the engine. But at my next stop at almost 500km-I let the engine cool down again to 93 degrees-poped up the hood and keept her in shade for about 20minutes! I restarted the engine half an hour later and had the same issues again! Can anyone help me?

 

On your trip, did your altitude/air pressure change significantly from location to location, like, if you were driving through the mountains or driving and stopping during changing weather conditions?

Altitude and air pressure fudge the hell out of my idle with the Power FC. No amount of redoing the idle learn or trying to set the idle EVER works with my car because air pressure in my neck of the world changes, sometimes, hourly. No joke. I know for the first bit when you get your computer, you're supposed to drive as close to same temperature, pressure and elevation until the idle stabilizes, but that's sometimes just impossible to do in a temperate climate.

 

No actually the climate was very stable and I didn't past any mountains at all...I only know when it is cooled down completely it starts perfectly without any issues!

 

there are a lot of threads in the 3rd gen section about adjusting the throttlebody to help stabilize the idle on the Power FC. it doesn't always solve every problem but it helps