Smart Cars

[HGGuate]

The smart engineering that Porsche hides in its cars management systems does not cease to amaze me. After a few years with the car, I keep finding smart features that I had never heard of or read about in my owners manual.

Yesterday after a few hours of spirited driving in back country in my 1998 Carrera (996), I returned to the city and found a huge traffic jam that had me almost at a standstill for a half hour. Predictably, the engine temperature started going up (not to redline, but close to the 120 mark)

At one point the car idle speed started behaving strangely (Idle would drop from 1800 to about 1200 rpm for a second or two and would then go back up to 1800, cycling back to 1200 after about a second or two). The AC fans did not stop blowing, but the System stopped cooling the air while the engine temp was high.

We got past the traffic jam and driving at 40 KM for a few miles and the phenomenon stopped (idle went back to normal and AC started cooling again.) Once again we hit traffic and as the engine temp climbed once again, the Idle change and AC cutout came back until we started moving and the temp dropped back to normal ranges.

I have tried to find info on this motor behavior on Renntech, my owners manual and a few Porsche resources I have in my library but have not found any information detailing this or other protection mechanisms the car has.

This behavior may seem like a trivial (and logical) behavior to expect from the cars computer, what surprises me is that it was included in the electronics of a car built in 1998 and probably designed years before that.

I would love to hear about other engineering quirks Rentech readers have found through the years with their Cars, the manual only goes so far to instruct us about our "babies".

[wvicary]

At wide open throttle the AC is disengaged to reduce parasitic losses so the engine can develop max HP.