Free Mods!

IAT Sensor

I read about the IAT sensor on KRCs page and decided to try it. I did it on my 94 318 Grand Cherokee. I didn't feel anything really and my MPG sucks more!!! (of course 7" of lift and 10 offroad lights don't help) BUT, I had all that before. I have, for performance/mpg, K&N FIPK, jet chip(no programmer made for that grand), 180* t-stat, bosch platinum +4s, lower resistance plug wires, and I never run the A/C in it. I was curious if anyone else had experienced a lower mpg with that mod? Oh, does anyone have any experience with the Speed Sensor calibrators? I decided to fork out 140 bucks to see if that would help my shifts/mpg/power b/c I read that it messes with fuel when you have larger tires or a different ratio gear(in that with larger tires the vehicle acts as if it is going slower and supposedly pumps more fuel into the cylinders). Confusing I know, as soon as I install the calibrator I will post my observations.

Sam Cler said:

The IAT mod will worsen your fuel economy. It will read a cooler intake charge and pump more fuel into your cylinders.

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Ok, this clarifies what my rambling was about... Thanks... I was under the impression that a colder temp reading would cause the engine to run lean b/c of the more dense charge of air... and that with warmer readings it would cause it to pump more fuel to the engine... I see that I had that completely bass ackwards... However, I have also been under the impression that most engines perform better in more lean fuel/air ratios.

Sam Cler said:

Better fuel economy through sensor mods would require advancing the timing, such as the CPS mod.

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I don't think the Jet chip will allow me to do that will it? I want to get optimum performance and mileage out of this vehicle the way I have it, so i want to do everything I can to make it do just that.

Sam Cler said:

The fuel flow isn't directly effected by the tire size or gear. If you don't recalibrate your speedo after you get a different sized tire then your mpg will not be correct.

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So in a sense the odometer/tripodometer are off too? Or is it just the computer? I have the jet speedo calibrator for this, not yet installed, but I'm really curious as to how far "off" my jeep is as a whole...

Sam Cler said:

If you have a numerically smaller final gear ratio (bigger diameter tires without re-gearing,) then during acceleration you'll be loading your engine more and dumping lots of fuel in there. Having a numerically higher final gear ratio (smaller diameter tires or higher numerical gears,) will give you better mechanical advantage and load the engine less.

On the freeway the opposite will happen. Because you don't need a lot of horsepower to maintain a constant speed, a numerically smaller final gear ratio will give you better fuel mileage.

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This I understand. The numerically lower gearing will make you use more of the pedal to get up and go. My driving is generally 55-70 mph for about 20-30 miles.

And to keep on topic...
#1--You can do some engine dress up with wire covering, just replace the old/dirty covering to make it look better.
#2--You can also go in and clean up ratnest wiring by re-routing and using black electrical tape to conceal all of it wrapping it tightly(this also helps prevent wiring problems).
#3--Take off body panels, fender liners, cowl grills, grills, and anything that comes off and clean under it, you'd be surprised what you will find and how much cleaner your truck will look.