TwinTurbo.NET: Nissan 300ZX forum - "inacuracies to correct"
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Subject "inacuracies to correct"
     
Posted by Kenny on August 03, 2006 at 2:41 PM
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In Reply To no question.. just want to get some information out there posted by AntiHero on August 03, 2006 at 02:25 PM
     
Message MAF:

pros
-Accurately measures the air entering the intake tract under almost all conditions

Not when there is excessive turbulence near the air inlet.

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

That's pointless, just recirculate the valve.

, or you can utilize a blow through MAF system where the MAF is after the turbo and also after the BOV.

Again, no reason to do that.

-the z32 maf has a maximum measurable airflow that is roughly equivalent to 500hp or so.

The limit is the voltage the MAF can send to the ECU. That's something of a misnomer above.

-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.

It's not a horsepower limit, it's a voltage limit. There's no horsepower limit.

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.

That's pretty moot for the Z32.

MAP:
Pros:
Ease and flexibility of install. Much smaller sensor then a maf sensor, and its simple to find someplace to put it.

It's even easier to use the stock MAF.

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 .

Right, like tuning MAF.

-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.

Recursively Yours,
Kenny...

PETZ Member #5





     
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