Weird Cooling Issue - anyone seen anything like this?

[Chythar]

Most definitely.

That's what I thought. Then, it seems likely that the ECT is bad causing the computer to stay in warm-up mode. Only one way to find out.

I have the basic Innova/Equus code scanner, but it doesn't read live data. Is there a code reader for OBD1 that will report sensor data, such as the ECT? Or is that only available for OBD2?

 

[HISSIN50]

Auto Xray, Innova and a few others make OBD-I readers for our cars. Look for something that can view PIDs. Amongst those read is ECT.

You can also simply check voltage readings at the ECT and interpolate them. The ECT uses a thermistor so dont be surprised to see voltage and resistance be related (not inversely). I typically check the readings at about 100*F (my ambient temp) and then at 180*F (operating temps).

One quick question: You don't have the aftermarket temp sender in the t-stat housing do you? If so, it can be normal for it to jump around because the stat affects the reading.

 

[Chythar]

Auto Xray, Innova and a few others make OBD-I readers for our cars. Look for something that can view PIDs. Amongst those read is ECT.

You can also simply check voltage readings at the ECT and interpolate them. The ECT uses a thermistor so dont be surprised to see voltage and resistance be related (not inversely). I typically check the readings at about 100*F (my ambient temp) and then at 180*F (operating temps).

One quick question: You don't have the aftermarket temp sender in the t-stat housing do you? If so, it can be normal for it to jump around because the stat affects the reading.

I'll check out the code readers, thanks. I haven't installed the aftermarket temp sender yet (due to laziness). But when I do, I will be moving the stock temp sender to the t-stat housing and the aftermarket sender to the stock location. I've read enough about that issue here to know better. Thanks for checking, never hurts.

 

[STM1965]

thanks for info guys!

 

[Chythar]

Heh, I should follow up on this one. The problem was my ECT, a new Motorcraft one fixed the problem. Temp stays down to reasonable levels on city streets; if it does rise a bit high, it will drop down as long as I'm driving at least 35mph. And my gas mileage is up too.