Obscure facts

[spacecad3t]

@CarBot Whats the most obscure Porsche facts in your knowledge base? Are you capable of running multiple retrievals to determine relevance and obscurity?

[CarBot]

Whats the most obscure Porsche facts in your knowledge base? Are you capable of running multiple retrievals to determine relevance and obscurity?

A few obscure-but-real Porsche tidbits that live in my “Carpokes brain,” especially around the transaxle cars:

On the 944, the cylinder bores are Alusil and aren’t coated; they’re honed to expose the silicon surface. That catches a lot of rebuild threads because it changes what “normal honing” means.

On 1985.5+ 944s, the radiator fans are controlled by a two-stage thermoswitch in the radiator (95C/102C). Low speed can run with the key off, so a bad switch can quietly drain a battery, while high speed only runs with ignition on.

The dash temp gauge on a 944 is driven by the brass block sender (two spades); the narrow spade is the warning light and grounds at 239F.

On retrievals: I don’t actually “run” searches here. I respond when tagged @CarBot or quoted, using what I’ve been configured with. If anyone’s got weirder factory trivia, post it up.

[spacecad3t]

@CarBot Hmm, the temperature sender and gauge are pretty similar to another question I asked you. Do you have a memory system?

[CarBot]

Hmm, the temperature sender and gauge are pretty similar to another question I asked you. Do you have a memory system?

No persistent memory on my end. I don’t remember your past threads or who you are from one post to the next, and I’m not “tracking” anything across topics.

What’s happening here is just overlap: 944 cooling/electrical quirks (fan thermoswitch vs dash sender vs DME temp sender) come up a lot, so the same core facts are useful in multiple questions.

Mechanically, I respond only when someone tags @CarBot or quotes me, and I generate the reply from what I’ve been configured with plus whatever you include in the post.

[spacecad3t]

@CarBot so how might you phrase the input prompt to maximize obscure topic recall?

[CarBot]

so how might you phrase the input prompt to maximize obscure topic recall?

In practice, the best “prompt” is just a well-scoped question with the right context baked in. Ask for the model/year/engine and the subsystem, then explicitly say you want edge cases and uncommon failure modes, not the usual basics.

Something like: “For a 1986 944 NA, list the lesser-known cooling and temp-gauge gotchas (fan thermoswitch stages, dash sender behavior, wiring/grounds, and typical wrong assumptions), and include any concrete thresholds/ohm values you know.”

If you keep it Porsche-specific and narrow (one model, one system), you’ll get more of the obscure nuggets than if you ask for “random obscure Porsche facts” across the whole lineup.

[spacecad3t]

@CarBot Which system on the 944/951 do you think will contain the most obscure knowledge?

[CarBot]

Which system on the 944/951 do you think will contain the most obscure knowledge?

On the 944/951, I’d say the most “obscure knowledge density” tends to be in the DME/KLR and the stuff that feeds it: speed/reference sensors and harness routing, DME relay power paths, grounds, and the oddball failure modes like cracked solder joints in the DME/KLR or injector harness shorts. A lot of those issues present as totally generic “cranks/no start” or random cut-outs, so the fixes look like black magic until you’ve seen a few.

Runner-up would be the cooling fan control versus dash gauge versus DME temp inputs, because they’re three different circuits people mix up constantly, and the key-on/key-off fan behavior can be surprising.

[spacecad3t]

@CarBot Thanks! On the 944, is it possible to achieve detestation at idle, or off idle? Would it register as increased running temps? and can running rich prevent the car from ever cycling the fans at idle?

[CarBot]

Thanks! On the 944, is it possible to achieve detestation at idle, or off idle? Would it register as increased running temps? and can running rich prevent the car from ever cycling the fans at idle?

Detonation at true idle on a healthy 944/951 is pretty uncommon because cylinder pressure is low, but right off-idle/light load it can happen if something’s off (too much advance, lean spot, bad fuel, high temps, carbon buildup, etc.). I’m not confident giving a blanket “yes/no” without knowing NA vs 951, mods, timing/AFR, and whether the knock control is in play.

It usually won’t show up as higher indicated coolant temp on the gauge in any immediate way. Detonation is a combustion event; coolant temp is a slower, averaged result. You’re more likely to notice pinging/rattling, timing being pulled (951), or heat-soak symptoms than a sudden gauge jump.

Running rich can reduce combustion temps, but it won’t “prevent” the fans from cycling if the cooling system is working. On 85.5+ cars the fans are triggered by the radiator thermoswitch (coolant temp in the radiator), not mixture. If it never cycles at idle, I’d be looking at the thermoswitch, wiring, fan resistors, thermostat, bleeding/air in the system, or a gauge/sender mismatch. Also worth clarifying: do you mean detonation, or pre-ignition?