Heated Intake / WAI
I cut a hole in the bottom of the airbox and stuck a power steering cooler over the opening. I just used some Tees to get hot coolant from the heater core. It seems to add about 15-30 degrees to the incoming air according to the ECM.
I got quicker warm-ups and 1-2 more mpg when it was below 50 degrees outside. The power steering cooler isn't really big enough and can't keep up at higher speeds, probably because the engine is drawing air in faster than it can transfer heat. I found that 1985 Chevette's had a very small 6wide x 6 long x 2 deep heater core that has a lot more surface area but I'm not convinced that it would be worth the cost and effort of hacking up the air box more. Maybe before next winter.
The current set up gets to about 100 degrees when it is 70 outside and I have not recorded any significant differences. This is a MAF engine. I do not have the tools to read and write this ECM, but I have a bin from an '05 Mustang 3 valve 4.6L and the ECM does not start to subtract very much fuel until you get into the 150F and above range in MAF mode. MAP mode (speed density) has a bigger fuel cutoff, but honestly, you'd probably be getting bad mileage just from running in speed density mode. Plus I'm not entirely sure this engine even has a MAP sensor, I think it just goes full blown limp home mode with fixed timing if the MAF fails (unplugged). I could trick the ECM by changing the IAT value with a potentiometer, but I don't want to run too lean and overheat the 4 catalytic converters or risk detonation because Ford didn't include a knock sensor on the 2002 model year
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I'm going to try to retest it on a few more very controlled runs and then move on to the next idea