MAF mod questions (4.0 sohc)
I keep seeing threads about the MAF mod and understand the concept, but I can’t figure out exactly what’s suppose to be done, I have a 02 4.0 sohc and this is what my MAF looks like, pointers on what needs to be modified?
https://cimg5.ibsrv.net/gimg/www.ran...b95bf3355.jpeg https://cimg6.ibsrv.net/gimg/www.ran...57d5edd1e.jpeg |
MAF = MASS air flow
Mass being the key word, MAF sensor is there to WEIGH the incoming air, MAF data is used by computer to calculate the MASS of the in coming air 14.7:1 gasoline air:fuel ratio is a WEIGHT Ratio 14.7 pounds of air to 1 pound of gasoline 14.7 grams of air to 1 gram of gasoline This is why Fuel Injectors are rated in POUNDS of gasoline per hour, not gallons or liters, POUNDS, because its a weight ratio Cold or warm, gasoline's weight doesn't change much Cold or warm, air weight changes ALOT It's how Hot Air balloons work, "hot air rises", why,? Because its lighter than cooler air, so a balloon filled with Hot Air will float up above the cooler air around it You can add more gasoline to colder heavier air because mix is a WEIGHT ratio, its why people use Cold Air Intakes(CAI), all 1986 and up Rangers come with that, just FYI When you can add more gasoline you get more power released If you just add more gasoline you get a flooded engine not more power, lol If you think the size of the MAF passage is restricting air flow to the engine at WOT(wide open throttle) then a larger diameter MAF may be needed, but stock size is plenty for stock 4.0l SOHC Diameter would only be an issue if you modified the engine so it could use more air at WOT On any engine you can hook up a vacuum gauge you can see in the cab Then find a stretch of road that you can run at WOT and higher speed, no police around, lol At WOT you should see 1"-2" of vacuum until Valves Float and it drops to 0" Over 2" could mean a restriction, on intake air OR Exhaust OUT MAF sensor itself only samples say 15% of the incoming air, this % is programmed into the computer, computer then calculates total air weight from this So changing the diameter of the opening and using same sensor would throw off that %, so throw off computer calculation There is also an Air Temp Sensor, IAT or ACT, used in conjunction with the MAF data to calculate air weight so computer can added correct weight of gasoline To get more power from any engine you need to get it to use more air, so more gasoline can be added Thats what "larger Cams" are for, engine gulps a bit more air thru the valves Or what turbo or super changers do, FORCE more air into the engine so more gasoline can be used at the 14.7:1` ratio And of course larger displacement, 5 liter engine can gulp more air than a 4 liter engine, so can use more gasoline at 14.7:1 and get more power released Car makers sell performance, so most stock systems are the best that stock engine will do Back in the 70's and early 80's car makers had to detune systems to meet emissions requirements, those days are long gone now, better engine designs and Cat Converters mean engines can be tuned for best performance |
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