Turbo afterrun system question

Phil Rose pjrose at frontiernet.net
Thu Nov 27 12:43:37 EST 2003

>On Wed, 26 Nov 2003, Phil Rose wrote:
>>  It's possible  that the afterrun switches have poor quality control
>>  (i.e., large variability in the set point temp), or perhaps the
>>  afterrun relay has a tendancy to be (or to become) "out of spec",
>>  whatever that may mean.  What's left? Well, I suppose wiring harness
>>  faults, or even car-to-car differences in engine/turbo cooling
>>  efficiency. A great mystery, but one not to fret much about unless
>>  you find that your afterrun _never_ functions. Then there's always
>>  the old work-around of allowing 30-60 seconds of idling before
>>  switching off the engine whenever the turbo has been pushed hard.
>  > Good time to meditate, take deep breaths.

>Somebody told me that after hard driving there must be 1-5-10 minutes
>(depending on how "hard" it was) idle period, otherwise some of the engine
>oil will "cook" in the turbo. No afterrun will help this - it's cooling
>capabilities are not so great as oil cooling.

Yes I agree. I should have said "pushed a little" rather than pushed 
hard.. In this instance by "pushed hard" I was thinking of something 
a merely just little beyond everyday, casual trips to the grocery 
store--but not hard enough to produce incandescence. After really 
hard use--track sessions, for example--I always allow at least 5-10 
minutes of idling/cool down. Of course the need for a certain 
cool-down time is mitigated by how much low-speed (unboosted) driving 
you're able to do before stopping.

>If I use my a200q20v for everyday driving - afterrun does not activate,
>because engine temperature is not so high. There are some exceptions, when
>wheather is very hot, and the climat control on - engine temperature goes
>up after I switch off engine.

But certain others (i.e., some '91 200q owners) claim their afterruns 
cycle on virtually _every_ time they turn off the engine. This 
implies a distinctly different afterrun behavior than with those of 
us, like you and me, who have afterruns that rarely operate after 
moderate, everyday driving. Of course, I suppose that those "others" 
might never drive moderately. :-)


Phil Rose
Rochester, NY
mailto:pjrose at frontiernet.net

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