From the other thread
Says I shouldn't have a cooler and I don't. I don't know why this wouldn't be reflected in EPC.
07 S550: thermostat
Re: 07 S550: thermostat
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Re: 07 S550: thermostat
Acting up more consistently now. Seems like maybe after 21 minutes it smooths out finally but that also could be because that's about when I get off the highway.
So I gave up and ordered another one. I guess if this next one acts up I will have to reconsider my options.
So I gave up and ordered another one. I guess if this next one acts up I will have to reconsider my options.
Re: 07 S550: thermostat
Acted up yesterday morning but the afternoon was warmer and it was fine. It's almost like there is a temp range where it is sticky or something like that.
Re: 07 S550: thermostat
Pressurized to around 15 psi and checked for leaks. Found none.
Replaced the thermostat again. 152k.
Shots of the job and the thermostat I put in around late Dec/early Jan. I see nothing wrong with it. This was extra easy because the gasket came off cleanly and I tried harder to avoid moving the air pump out of the way and succeeded. I vacuum filled and also ran the engine with the heater maxed. And the new thermostat My small pile of thermostats.
Shots of the job and the thermostat I put in around late Dec/early Jan. I see nothing wrong with it. This was extra easy because the gasket came off cleanly and I tried harder to avoid moving the air pump out of the way and succeeded. I vacuum filled and also ran the engine with the heater maxed. And the new thermostat My small pile of thermostats.
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Re: 07 S550: thermostat
Road test and decided to monitor thermostat duty cycle, coolant temp and target coolant temp. I've never really done this before so I have no data. The results are extremely interesting.
Basically what it does is drop the duty cycle to zero which targets 211F or so. Perhaps this is the natural control temp of the thermostat (mechanically). Then at first it seemed to randomly target like 176F and crank the duty cycle to 99%. Once it was able to pull temps all the way down (and sometimes as low as 173F) it seemed to raise the target again and drop duty cycle to 0%. However, if I was heavy on the throttle (and I mean only for 3 seconds) it would once again raise duty cycle to 99% and target 176F. Only when it achieves something in this range will it raise the target again! If I am easy on the throttle, it seemed to just stay at the target of 211 and actual coolant temps were like 206-212 or so. This is so odd. I really wish I monitored this with the previous thermostat. However, I do have evidence of it failing its own test. I guess I should run the test again on a brand new thermostat and see what it does.
Hypothesis: whacky temp control but the old thermostat was also misbehaving. More to come I guess.
Basically what it does is drop the duty cycle to zero which targets 211F or so. Perhaps this is the natural control temp of the thermostat (mechanically). Then at first it seemed to randomly target like 176F and crank the duty cycle to 99%. Once it was able to pull temps all the way down (and sometimes as low as 173F) it seemed to raise the target again and drop duty cycle to 0%. However, if I was heavy on the throttle (and I mean only for 3 seconds) it would once again raise duty cycle to 99% and target 176F. Only when it achieves something in this range will it raise the target again! If I am easy on the throttle, it seemed to just stay at the target of 211 and actual coolant temps were like 206-212 or so. This is so odd. I really wish I monitored this with the previous thermostat. However, I do have evidence of it failing its own test. I guess I should run the test again on a brand new thermostat and see what it does.
Hypothesis: whacky temp control but the old thermostat was also misbehaving. More to come I guess.
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Re: 07 S550: thermostat
Found some info in WIS. Some of this seems to be like M276 era info and probably a little hotter temps than my M273 runs. Also, I checked the resistance of both my original thermostat and the one I had in there earlier this year. They were both around 15.8 ohms which is within spec...
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