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2006 chevy trailblazer_ls
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The temperature gauge is controlled by a wire hooked up to the sending unit that measures resistance. Its not exactly the most accurate reading, but its good enough.

Some performance chips or tunes require a 180 thermostat because the computer is tuned for that setting, its better for hotter climates like California weather or in the summer. If you have a stock PCM and use the lower thermostat it could cause your engine to stay in closed loop operation, there are alot of things that go on during this stage but nothing is really affected .. its mainly just an operation of the PCM where it learns its own running conditions, etc etc.

- Dan
 

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Ddubb said:
If you have a stock PCM and use the lower thermostat it could cause your engine to stay in closed loop operation,
- Dan
I think you meant that it will stay in open loop (not closed loop) if the proper operating temperature isn't reached.
 

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2006 Blue TB SS said:
I think you meant that it will stay in open loop (not closed loop) if the proper operating temperature isn't reached.
Actually, I think he knew what he was talking about - AFAIK closed loop means that the fluid does not run through the radiator at all (it is 'closed' out of the system) until the motor reaches operating temp, at which time the thermostat opens. Open loop would mean that the thermostat is fully open because the fluid is so hot that it needs to be run through the radiator.

I could be wrong on this, however. :undecided
 

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I thought we were talking about the PCM... could be that I flapped my gums too quickly before really having read his post :x .

Generally when talking about open vs. closed loop one tends to be talking about the control program on the PCM.

I'll go back and sit quietly in my corner :x
 

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No need to go back to your corner. You were correct '2006 Blue TB SS', Ddubb was referring to PCM operation, in which case he should have said "Open Loop" instead of "Closed Loop". Coolant flow through the radiator is not the determining factor for PCM Open/Closed loop operation.

When you first start the engine, the computer is in open loop as it waits for the operating temperature to hit a preset threshold. During this time, the engine is running on a pre-determined set of default computer settings, and not entirely operating the engine off of feedback from the different sensors. Once the threshold engine operating temperature is reached (and I presume some other specific sensor thresholds), the computer switches to closed loop operation, where it uses feedback from the various sensors to control the engine. This is a universal concept across all modern age vehicles, although, obviously, the settings and sensors differ from case to case.

Open loop and closed loop are standard control circuit terms not specific to computer/engine operation. In all cases, closing the loop means feedback from sensors are being used to control. Open loop means that some or all of the sensors are ignored and control is performed through some preset group of parameters.

There will be a quiz at the end of the week. :D :dielaugh:
 

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TB SS said:
There will be a quiz at the end of the week. :D :dielaugh:
oh no, I got a C in linear control systems... and that was pure luck!
 

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PbFut said:
Is the gauge buffered? Most of my recent experience with newer auto technology has been with the BMW make. On both of my BMWs, the temp gauge is buffered. The temp can move around some but gauge stays put. If you start overheating, the gauge quickly rises. It doesn’t go to red line but you know you are running warm when it moves. I am not sure the logic behind it. Did Chevy adopt that same process on the SS? My gauge hasn't moved off 210 for 1700 miles, except warm up. If it’s not buffered, that Tstat is doing a good job.
In reply to a couple previous post on lowering the stat. If the engineers designed for 210, why drop the range? Or is 210 to lower emissions at the expense of power?
I have read on some of the LS1 forums that GM was getting to many people complaining that the gauge was moving all over the place (running hotter when sitting still and then back down). Therefore, to cut down on warranty complaints the gauge is set to stay at 210 over a wider range (e.g. it will read 210 when the temp is actually between 190 - 230)
 

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My Tahoe is a '99 and it sits at 90°C ALL the time (although it has the towing package, so there's no shortage of cooling). My '95 Camaro always sat at the same temp after warming up too, could just be a smallblock thing maybe?

G
 

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Discussion Starter #31
RacerXDJN said:
I have read on some of the LS1 forums that GM was getting to many people complaining that the gauge was moving all over the place (running hotter when sitting still and then back down). Therefore, to cut down on warranty complaints the gauge is set to stay at 210 over a wider range (e.g. it will read 210 when the temp is actually between 190 - 230)
Ha! Leave it to GM to offer full instrumentation instead of idiot lights, then configure the gauges to work just like...you guessed it.:rolleyes:
 

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Kybuilt said:
I was looking over some pics in the SS gallery and noticed someone's dashboard pic plainly showed the temp gage at 210 degrees. So I made a point to look at mine the next time I drove it. After it's fully warmed up, it never drops below 210 degrees! Has anyone else noticed this? Is it a gage anomaly or do these have a 210 degree thermostat?
I apologize in advance if this was already said, but I didn't want to read through 3 pages...Your temp is fine, and as some have said is probably in the 190 range. GM, like most oems know we want gauges, but also know a lot of people would be in the dealer every other week thinking there were issues if their gauges were off a little...so they actually build in a comfort zone and most gauges actually just read in the middle of that zone...IE, your 210 reading is just in the range of normal on the gauge, but in actuality it's no where near correct.

bottom line is not to worry.:thumbsup:
 
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