| Ok, we have been having a lot of discussions about Manifold absolute pressure (MAP) vs mass air flow (maf) engine control systems. Let’s have a respectful intelligent debate so we can make the information available. lets start with the basics. from wikipedia, just to get started: "An engine control system that uses manifold absolute pressure to calculate air mass, is using the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation. Not all fuel injected engines use a MAP sensor to infer mass air flow, some use a MAF sensor (mass air flow).
A mass flow sensor responds to the amount of a fluid (usually a gas) flowing through a chamber containing the sensor. It is intended to be insensitive to the density of the fluid."
Ok, so now lets take a look at the pros and cons of each system.
MAF: pros
-Accurately measures the air entering the intake tract under almost all conditions allowing for the ECU to have accurate information in order to control the engine based on the true mass of air entering the engine. cons
-system leaks and atmospheric blow off valves allow previously metered air to escape causing the ecu to supply fuel for air that is no longer present.
-solution if you insist on BOV's you can either get an electronic correction device that will attempt to determine when the BOV vented and attempt to correct for it, or you can utilize a blow through MAF system where the MAF is after the turbo and also after the BOV. -the z32 maf has a maximum measurable airflow that is roughly equivalent to 500hp or so.
-this is not a true problem with MAF at all. Every sensor has limits, the one nissan put on the 300zx has a limit of 500hp. Use two of them or buy another MAF that has a limit that exceeds your needs. -the MAF sensor itself is an intake restriction
-this argument probably stems from the vane style maf devices which actually put a "paddle" into the intake tract and determined how much air was going in by how far open the air pushed the paddle. For a hotwire MAF this argument seems unsubstantiated. If you really need more flow, buy a bigger maf, they are readily available. MAP:
Pros:
Ease and flexibility of install. Much smaller sensor then a maf sensor, and its simple to find someplace to put it. resistance to contamination by oil or other substances. Maf sensors can be rendered inaccurate if allowed to be covered by contaminants. Cons: -Absolutely no true measure of air mass. A map sensor relies solely on the accuracy of the engine efficiency data stored by the ECU in order to infer the amount of air in the engine. This means that the entire system is limited in accuracy to the efficiency table. Tuning requires skill and accurate measuring equipment . -No tolerance for change. Any change to the engines efficiency requires manual tuning of the system. A change might be something as simple as a new air filter, or exhaust part. everyone feel free to chime in or debate as long as you can support your claim. "my buddy got 50 horsepower when he put a map sensor on his car" is not an argument for map vs maf... thats an argument for a standalone engine management and the customized tuning that went into making it work.
Antihero
These 2530's ain't half bad ;)
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14:25:29 08/03/06
