Jeff Smith: We did a little digging and it appears that the low-coolant sensor on your car is located on the passenger side of the radiator tank. It is difficult to see and you may need to remove the battery to access the sensor.
Apparently the sensor is tied only to the light on the dash, so it does not contribute to illuminating the check engine light. It also is somewhat troublesome, and corrosion or debris in the cooling system may arbitrarily trigger the light. So if you want, you can merely unhook the connection and go back to manually checking the cooling system level.
As for your engine temperature concerns, it first sounded like the gauge you were using may not be accurate (which is a common problem, especially with factory gauges), but looking into the factory fan settings, it appears these high temperatures were intentional. The first coolant-fan-switch temperatures we found were in a Hypertech instruction manual that indicated the factory ECU triggers the fans full on at 240 degrees F and turns them back off at 225 degrees F. That's a bit warm for a typical summer day that could easily kick your under-hood temperatures well over 240 degrees F. The Hypertech Power Programmer III that we looked at has the capability, among other things, to reprogram the electric fans to kick on at two different temperatures depending on your choice of thermostats. With the 180-degree Hypertech thermostat, the fans will kick on at 213 degrees and shut down when the engine temperature falls to 205 degrees. Or, you can opt for the 160-degree thermostat, and the programmer will trigger the fans to come on at 192 degrees and shut off at 185. This second option seems to be the most ideal as it will keep your engine operating somewhere around the 190-degree mark.
The reason the factory intended these engines to run so hot was strictly to satisfy emissions demands. Higher engine operating temperatures reduces hydrocarbon emissions, but it's certainly not the ideal situation for making power. Higher coolant temperature also increases the intake manifold and cylinder head intake port temperature. This heats the incoming air and fuel, which may improve mixture vaporization, but more important, it heats the air, making it less dense. This makes less power and also makes the engine more prone to detonation. The only snag we see with the Hypertech Power Programmer III, (PN 345752) is its $399.95 price, which seems a bit steep just to change the fan temps. The programmer can also allow you to change the rev limiter, speedometer calibration, and shift firmness and timing along with a slight change in timing and air/fuel ratio to produce a little more power, but you didn't mention those items. Jet also makes a similar GM programmer that offers the same features plus it shows a slight gain in power with some additional tuning. The Jet Stage 2 Power Control Module is PN 19614S and sells for $329.95
We also spoke to Mark McPhail, an ex-GM engineer who has worked with us on many Car Craft projects and who now does aftermarket ECU programming and tuning. You can contact him about doing a simple reprogram of your ECU that will trigger the fans at the exact temperature you want for much less than $400. Plus, McPhail might also be able to pull a few other reprogramming ideas out of his electronic bag of tricks if there is something specific you need. Regardless of which option you choose, the engine should make a little more power just by running about 40 degrees cooler!
Jet Performance Products
Huntington Beach, CA
Costa Mesa, CA