ECT questions

99FiveOh

15 Year Member
May 20, 2006
2,051
20
99
J-Ville, FL
I've done some searching.. I know I know amazing huh! :nice:

Anyway, I found a chart oe resistance/voltage values to actual engine temps.

I fixed my fan problems with a new plug and now the fan operates nicely. Only trouble is, the fan is coming on too soon.

I started the car and let it idle for about 3 min and the fan kicked on, this before the gauge in the car even got to the "N" in normal. I went to look for my multimeter and let the car run. When I got back the dash gauge read slightly past "N". I took some readings and what I got from the harness probe was .79 volts on the ECT side. Then I pulled the ECT connector and tested resistance at 3.88 kohms. So those two readings point to an actual engine temperature of around 176* F.

This means the gauge inside the car is actually pretty accurate. I always suspected the gauge would read right in the middle when you reach the intended 196* temp.

Anyway, my question is, isn't the fan supposed to come on at a much higher temp? I mean, it's not a bad thing that it's coming on sooner than later, but this could also mean that the EEC is seeing inaccurate temps for it's fuel mapping.

I just curious as to whether this could have a warm start/stall, hunting idle effect. But I'm confident that the ECT is reporting the proper temp.

Hissin, this is your cup of tea, what do you think? Does it sound like the ECT is ok to you?
 
The low speed should not come on till about 208*F (which is closer to the intended temp - remember the OEM stats have a great deal of hysteresis built into them and don't fully open till 205*ish).

Have you compared the ECT reading at the EEC to the reading at the sensor?
 
It's almost SOP (with a tune) to lower the fan thresholds to accommodate a 180* t-stat. If your fan comes on in the 170's, it was probably programmed for a 160* t-stat. One generally does not want the fan to come on before the t-stat is open all the way.