Good idea, so much work for a few degrees.
Congrats on the project.

But, how long have you driven since the mod?
I know there is a code for the coolant not reaching proper operating temperature (like the thermostat is stuck open)
Wonder if running at 195 will trigger it...

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I guess I didn't think it was a lot of work. Well, almost 30 degrees, but is variable. So if for some reason I wanted it at, say, 210, then that's easy. However, 195 is well within its normal operating range. As I said in the post; even stock I could drive the temp down that far under a sustained load (keeping the injector pulse width above the computer's threshold for activating the thermostat itself).

I guess it's been a couple of weeks. It took some time to write all that up, and I had to take a road trip for a couple hundred miles during that time.

Slick, I guess I didn't pay enough attention before, but your 4.8 (DME 9.2) is a little different. And, your car runs quite a bit cooler (stock) than the earlier 4.4s do under DME 7.2. You have wide-band oxygen sensors, so your system can actively control your engine across a much wider range of conditions. The concepts all still apply, although your sensors are a little different, and the connection points, while all still there in your system, are also different.

While I could give you the revisions to the circuit, you would first have to provide me with the temp sensor transfer function on your car (voltage vs. engine temp), and you'd have to talk someone into building it and seat-testing as I have no way to do any on-vehicle checking here. But, personally, I don't think it's worth the effort given you aren't running way up there in the mid-220s all the time like the 4.4s are (and I'm pretty sure the 4.6s as well). You 4.8 folks have more the more evolved control systems.

Well now, then I unsubscribe.

lol.

Just kidding, if nothing else, this was a terrific read. I am still going to follow the topic, as nothing like this has been done before.

Keep us updated on how the unit is functioning going forward. Good job no matter how you slice it.

I ordered the components and waiting for a new thermostat. I still don't know if I can replace just the heating element vs. the whole termostat.
I got the LM2902N for the Op Amps that has the operating temperature (−40°C to 125°C) for here at North Pole :)

Although it is winter and quite cold here for some reason the engine temperature was between 108-110C and sometimes 111C.
Finally, yesterday I installed the temperature controller based on civdiv detailed instructions and the temperature is around 93-94C so far. I will monitor and see.
I didn't have an oscilloscope but I used the exact values civdiv set the variable resistors and I measured the impulse to the heating element with a speaker (with a capacitor) since the frequency is in the audible spectrum.

http://i695.photobucket.com/albums/v...-27-27_755.jpg

http://i695.photobucket.com/albums/v...-27-48_127.jpg

http://i695.photobucket.com/albums/v...-53-14_297.jpg

and I found this orphan connector in the electrical box. Any idea what's this for?

http://i695.photobucket.com/albums/v...-46-19_480.jpg

looks like You are very your stuff,but Your engine is not a M62,it is a n62.

I wish. The N62 runs at 94C but mine is a 2000 4.4i with M62TU.

My main reason to lower the engine temperature beside the other mentioned here, it was the tranny 2-1 hard downshift problem (after rebuilt) which happens when the tranny oil temperature goes over 100C or so.

The tranny now feels like new.

My 4.4 N62 and the 4.8 N62 each run at a normal range of 96-103C regardless of outside temps. Towing is another thing altogether and temps (with the 4.4) can push 123C.

Good deal dude. :thumbup: Glad that worked out for ya. Once you consider what we're actually doing here, it's pretty basic - the trick was getting the dynamic range right. I like your clean build, too. :thumbup: I've been running mine for months now, and it's rock steady at about 91C, with maybe a 1 degree fluctuation under dynamic conditions.

And I dunno where folks are heading with the discussions immediately obove this one - with a 2000 you have the same engine and engine management system I do (and wrote the article about). Normal mechanical opening temp for that one is 108C, and you'll see higher occasionally. Under load, like a grade, the system uses the injector pulse width as a determining factor on applying voltage to the thermostat to begin lowering the running temp. Of course, that takes a little while, so by the time it does, the hill or load is probably past. Later on, DME 9.X changed a number of parameters. While close to the 7.2 (evolution, not revolution), the system went to wide-band oxy sensors, allowing the DME to actively manage the engine under lean cruise, for example. Ours can't do it, and, well, anyway, I've written enough about what's going on in our version in a variety of posts..