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Discussion Starter #1
I have posted before on the 987 water temperature gauge accuracy (http://www.planet-9.com/987-cayman-boxster-chat/34162-water-temperature-accuracy.html)

Now I have a 981 GTS, and I thought I'd found nirvana because it has digital readouts of water, oil temperature, oil pressure and voltage. But after a few weeks I could see the water temperature rise to 194F then stay there, resolute! Suspicious I hooked up my ScanGaugeII and just as I suspected, the digital readout is as good as the idiot analog gauge on the 987! I rises to 194 and then stays there, regardless of the actual water temperature. Want proof? Here it is:



Darn it! Why does Porsche think we are idiots? Or at least in no need of knowing the actual water temperature? Why have a digital display, giving the impression that an actual number is reflecting the actual temperature, if it doesn't actually indicate the real temperature?

Here's another shot to indicate that while the actual water temperature varies, the readout stays the same...



Note a 17F swing in actual temperatures, and no change in the digital readout.
 

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:thanks: Phil for the effort and now real insight.

Truly disappointing. I wonder what happens when engine actually does overheat? Do 981s also have an idiot light aka "normal WTemp exceeded" or does such an issue just throw up a "generic engine fault/issue"? Time to read manual again it seems.

But with today's digital tech (aka your ScanGaugeII) why would P do this with WTemp readout?? :crazy:

Just curious, but do the oil temp and pressure and battery voltage values seem reasonably accurate when measured with you SGII?

:cheers:
 

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I wonder what happens when engine actually does overheat? Do 981s also have an idiot light aka "normal WTemp exceeded"
No, above 221 the gauge moves appropriately. This has been discussed quite a bit. Noah posted something from the technical manual for boxsters. I'll leave it to him to provide the technical information.
 

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No, above 221 the gauge moves appropriately. This has been discussed quite a bit. Noah posted something from the technical manual for boxsters. I'll leave it to him to provide the technical information.
:thanks: chows4us

I guess I missed that thread. That it does change at some point makes "some" sense I guess. SEARCH it will now be.
:cheers:

UPDATE - Just searched 981, water, temp, Noah Fect within Planet-9 (dates of yesterday and backward) and same string via Google with no hits as to this issue. Maybe just not not my day or whatever.
 

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Discussion Starter #6
I drove to work today with the SGII connected, and here are a few observations from yesterday and today:
1. The actual water temperature is below the digital readout up to 194 (eg readout says 185, actual is 175)
2. The actual water temperature fluctuates a lot, but this is also what I found with my 987
3. I have not seen actual water temps above 218F yet.
4. Just as oil temperature seems higher in normal mode, and lower in Sport mode, so does water temperatures. This would make sense as Porsche is trying to have the engine run hotter to increase efficiency in normal mode, whereas in Sport or S+ modes, the idea is to keep things from overheating.

As for oil temperature and pressure, L-G, unfortunately the SGII does not read this. It could be a limit of the model I have, or the software. I am going to check if I can get software that allows me to read those things from the 981.
 

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UPDATE - Just searched 981, water, temp, Noah Fect within Planet-9 (dates of yesterday and backward) and same string via Google with no hits as to this issue. Maybe just not not my day or whatever.
I know this was brought up here before but do not have the post bookmarked. You can read his original post here.
 

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Discussion Starter #8
Thanks chow4us. I don't want anyone to think I am particularly worried about the temperature gauge/digital readout on the 981. I have been running a SGII since I bought my 2005 MCS, and have a somewhat unusual obsession with temperatures born of modding my supercharged MINI. That said, I posted so that owners KNOW about the readout. Many Porsche owners are surprised to find that the actual coolant temperature is something other than 175F or in our case 194F. I am not expecting to see 221F to determine if Noah Fect and his "it reads actual temperatures above 221F" statement is true--I really don't care. Now that I know how the coolant temperature behaves, I plan on removing my SGII and driving in blissful ignorance since there's really little I can do other than check the coolant level regularly, and check for leaks on my garage floor...which are extremely unlikely.
 

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Its cool. Its a hidden fact and I think Noah did the p-car community a service but highlighting this as clearly many of us, regardless of model, probably wondered the same thing.
 

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I know that I have also seen threads here about the guage being inaccurate. However, if Lime-Gold was unable to locate them I am not even going to try. I had resigned myself to the fact that it would read 194 up to, and including, the engine overheating. With all the current and prior discussion: the Rennlist link is the first I have seen about the readout becoming accurate over 221 degrees. Thanks chows4us!
 

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I have pretty much concluded that the water temperature is not particularly sensitive/accurate since my 08 CS. In the 981 as soon as I found out about the other 'guages', I set the oil temperature, oil pressure and volts to read. You can see these fluctuate in different conditions as expected. And, I pretty much ignore the water and focus much more on the oil temp and pressure. That gives me a much better idea of what is really going on............
 

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Noah figured this out and Noah gets the credit for correcting other people who thought it was an idiot gauge.:) I just happened to read it.
 

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Discussion Starter #13
I just got word from ScanGauge that the SGII cannot read oil temperature or pressure from the 981. Bummer...
 

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:thanks: Phil for the effort and now real insight.

Truly disappointing. I wonder what happens when engine actually does overheat? Do 981s also have an idiot light aka "normal WTemp exceeded" or does such an issue just throw up a "generic engine fault/issue"? Time to read manual again it seems.

But with today's digital tech (aka your ScanGaugeII) why would P do this with WTemp readout?? :crazy:

Just curious, but do the oil temp and pressure and battery voltage values seem reasonably accurate when measured with you SGII?

:cheers:
While some owners would like an actual water temperature gage and one that reported the actual temperature most would be upset by the swings in coolant temperature. And as soon as the coolant temperature read "212" the owner would either be on the phone to the dealer or PCNA or at the dealer asking about this.

I have had a coolant temp gage in another car and while the fluctuations/variations in coolant temperature didn't faze me it was interesting to observe just how much the coolant temperature changes under "normal" usage. (Might also mention I had an undampened oil pressure gage in this car too and the oil pressure gage needle jumped around, move around quite a bit. This too would I think tend to scare the average owner.)

Prompted by a high level of water in the engine oil -- discovered when out of curiosity I had the oil analyzed -- early on I connected an OBD2 code reader/data viewer to my Boxster's 0BD2 port and observed coolant temperature in real time and like my earlier car observed considerable change in temperature with no real movement of the temp gage's needle. Roughly I found that one needle's width change in position was a 10F degs change in temperature but over time I just really don't care much.

I use the coolant gage to know the engine is up to temperature, at least nominally up to temperature, and then give the engine some more run time to ensure every last bit of coolant and oil is up to temperature, before giving the engine the whip, but beyond that the coolant gage is really not all that important/useful.

The owners manual actually says this in so many words. I quote: Pointer to the left -- engine cold. Avoid high engine speeds and heavy engine loading. Pointer in the middle -- normal operating temperature. The pointer may move up to the red area when the engine is heavily loaded and outside temperature is high, but should return to "normal" when engine load is reduced.

With my Turbo I pay far more attention to the engine oil pressure. Not that I"m particularly concerned about a sudden loss of oil pressure, only that the oil pressure is a good indicator of the engine's operating temperature. For instance at idle if the oil pressure is down close to 1.5 bar I know the engine is "hot". (Not real hot cause the Turbo's cooling system is quite good and keeps the coolant temperature under control and I have observed this good control in ambient temperatures of 118F/119F.) If the hot idle oil pressure is higher than 1.5 bar but below 2.0 bar I know the engine temperature is not "hot" but just right. If the hot idle oil pressure is at or above 2 bar I know the engine is "cold".

As I have mentioned before on a trip through southern AZ -- this not too long after I bought the car -- with the ambient air temperature at times reaching 116F with the OBD2 code reader/data viewer connected I observed quite high coolant temperatures. 226F and not just for a short time either, but for a long time and for a number of miles even on the freeway moving at freeway speeds. The intake air temperature was 135F and while I had no way of knowing the engine compartment temperature every time I slowed down enough I could hear the engine compartment fan running. In spite of this temperature though there were no warning lights, even though the coolant temperature gage needle moved to the right quite far. (I wished I had taken a picture now as I do not really recall how far.)

Back home I went to the Porsche dealer and spoke with the service manager and gave him all the "telemetry". He contacted the factory about this and the word back was as long as there was no warning light there was no overheating and no need to worry. It was then that it became clear to me that in spite of the temperature gage the gage was really more for show than go.

Some time after on another trip I hit some road debris and busted the driver's side radiator. Coolant leaked out. Not too many seconds after the impact with the car trailing a cloud of water vapor behind the warning light came on, flashing: Low coolant. Then just before I reached the shoulder and turned off the engine the light went solid: over temperature. I do not recall what the coolant temperature gage reading was. The light had all my attention. Fortunately, after the radiator was replaced and the lost coolant replaced the car and engine were fine.
 

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In the 981 as soon as I found out about the other 'guages', I set the oil temperature, oil pressure and volts to read.
Hmm, I wonder if/when I add the compass to the display, I'll really only get "approximately North".:hilarious:
 

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I know this was brought up here before but do not have the post bookmarked. You can read his original post here.
:thanks: Chow so much for the link.

I have done a print screen for my LG Mechanical's folder.

Interesting that 194F is only 25% of the indicated min/max range of 36 degrees. I would have thought if they were setting a default/
fixed point within said range they would have picked 203F, ie, the mid-point. But Oh well what the H*** do I know; Must be some other good P engineering reason to set it at 194. ;)

:cheers:
 

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I have seen the high water temperature warning when my radiators were clogged and I was in stop and go traffic with outside temps at over 100F. Note though that before that warning sign comes on, the car already shuts down the AC and electric ports and starts to heat instead of cool.

:thanks: Phil for the effort and now real insight.

Truly disappointing. I wonder what happens when engine actually does overheat? Do 981s also have an idiot light aka "normal WTemp exceeded" or does such an issue just throw up a "generic engine fault/issue"? Time to read manual again it seems.

But with today's digital tech (aka your ScanGaugeII) why would P do this with WTemp readout?? :crazy:

Just curious, but do the oil temp and pressure and battery voltage values seem reasonably accurate when measured with you SGII?

:cheers:
 
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There is a Porsche technical document out--I'll post it when I find it--that states that the temperature indicator on the 981 will indicate 194 deg. F when the coolant is in the range of 185-215F, which is considered the normal operating range.
 

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Discussion Starter #19
OK, let me be a little pissey here: If they went to the trouble of giving us a digital readout, and it can display three digits, why have a step function readout, where it reads up to 194 (in my experience faster than the actual temperature) and then stays constant for some range of temperatures, then start reading out actual temperatures above 215F? (BTW, I have seen 218F on the ScangaugeII and the readout remained at 194--but I'm sure there's an measurement error of at least +-3F)
I also completely understand why the average consumer would get all wobbly if they saw the actual fluctuations in temperature, so the constant 194 provides gives us some kind of comfort and respite from our obsessions.
 

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I also completely understand why the average consumer would get all wobbly if they saw the actual fluctuations in temperature, so the constant 194 provides gives us some kind of comfort and respite from our obsessions.
^^^^ This. As an enthusiast, you are not the average consumer and know that the water temperature means nothing under normal conditions. Getting obsessed over it moving up and down might distract you from paying attention to the one temperature gauge you do care about, oil temperature. Once outside of normal conditions, then you start to worry. OTH, you do care about the oil temperature. You know not to nail the engine until the oil is up to operating temperature and if it gets way up there, you know to monitor it.

I've seen other cars that have an oil temperature gauge and no water temperature gauge at all. The average person doesn't care. And there is normally no need to care. It's not like its 1958 and people are putting tap water into radiators and gas station attendants are checking your water and oil every time you gas up.
 
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