I don't know very much about the late model 351 and 460, but I was wondering if the 351 or the 460 went to MAF from SD. If they did then when did they change over.

 

The 460 was never mass air to my knowledge, and if the 351 is in an F250 it probably isn't MAF either. The 351 was MAF in the F150's for sure with OBD-II in 96, and there might be a few 94's and 95's running around with MAF, but you'd be hard pressed to find one.

 

So the 1996 F150 351 was MAF? Thanks for the info.

 

What does a mass air flow system look like as compared to say, mine?

Ryan

 

There is an inline sensor in the air duct at the airbox, that's the MAF sensor.

 

that's it..?

Ryan

 

In terms of looks alone, the presence of a mass air meter (and single air filter outlet feeding the dual throttle body) is about all that looks different.

 

So then, how does this help? What does the air meter measure, and what does it change?

Ryan

 

The meter directly measures the air mass flow entering the engine. This is beneficial for aftermarket upgrades because changes in volumetric efficiency can be directly accounted for by the measured increase in air flow. The other system, speed density, uses the manifold pressure and engine speed to infer the amount of air entering the engine. This works fine for a stock or near stock engine, but once the volumetric efficiency increases beyond a certain point, the computer can't see the increase in air flow. All it sees is manifold vacuum, so it injects the amount of fuel it is programmed to at that manifold pressure (it will richen the mixture some depending on O2 sensor feedback, but it can only go so far). Stock for stock both systems work fine. The advantages of converting to mass air in these trucks comes not really from the method of measuring (instead of inferring) air flow, but from the sequential injection used on the mass air computers (opposed to batch fire injection on the truck speed density computers) and the ability to add more upgrades than on the speed density system. There is a point though, even with mass air where the computer will need to be tuned to run properly with some really extreme upgrades.