metroplex

My 2000 Ford Crown Victoria has both an ECT and CHT, but based on the PCM settings, I see that it only uses CHT for doing the calculations. The ECT is only used for the temp gauge in the Crown Vic.

I am not surprised if Ford ditched the ECT entirely and just relies on the CHT, because the CHT readings are usually a few degrees higher than the ECT as it represents the approximate temperature of the combustion chamber walls. The ECT data is useless for calculating A/F ratios.

mustang68w

In most all reciprocating(non-turbine powered propeller) aircraft engines, they have cht and egt(exhaust gas temperature) gauges and they are awesome. The thing that I don't understand about this is why if the car gets hot, the engine shuts down some of the injectors? In aircraft there are three ways the engine is cooled; first is air, second is oil and third is fuel flow. In aircraft you have a mixture lever to adjust the amount of fuel the engine is receiving due to changes in altitude. A secondary function of the mixture control is to send MORE fuel to the engine to help cool it down if the temps are getting too hot. So can anyone explain why the car does this?

metroplex

On the EEC-V / DIS COP Fords, the cylinders can be used to pump out air to cool down the engine. Part of the limp-home process for Ford modular V8s that have overheated is to alternate cylinders to cool down the chambers (4 are actually igniting fuel to provide power, 4 are just pumping air). The PCM is assuming that at 258F+, the cooling system has failed and that the engine needs to start pumping out the heat via combustion chambers. It can do this by shutting off fuel and ignition to individual cylinders.

mustang68w

makes sense, thanks

mot250

OK, so what is a good temperature to set the low and high speed fans if I'm running a stock thermostat? Seems my tune is set at 196 deg F (low speed) and 210 deg F (high speed).

And, would anyone suggest a cooler thermostat (for track use - road courses) and if so what temp and then what fan settings?

metroplex

The stock low speed fan is set to turn on at 216F, turns off at 208F.
The stock high speed fan is set to turn on at 228F, turns off at 224F.

Your engine works more efficiently when it reaches optimal operating temperature.

RRRoamer

But just keep in mind that "efficiently" in this case is actually referring to emissions and fuel economy, not necessarily maximum power. Usually for max power, you want to keep the engine a bit cooler than for best fuel economy and emissions.

metroplex

I've never heard of that, although you do want a cooler air intake stream to make more power. Plus, you want the engine cooler to prevent detonation from raising the ignition timing and/or compression. However, the engine's rotating parts will experience less friction if everything was at optimal temperature.

RRRoamer

True.

But "optimal temperature" for oil is a lot lower than "optimal temperature" for emissions and fuel economy. Manufacturers are going to set fan and water temps to minimize emissions and maximize fuel economy.

Period.

Power production is AT BEST number three on their priority list and probably closer to number five (behind fuel economy, emissions, cost and manufacturability).