85-96 Ford F-series 5.0/5.8l E4od Mass Air Conversion Kit F-150/250/bronco Truck on 2040-parts.com

Mass Airflow Conversion - Mass Appeal
How To Convert Your Speed Density Mustang to Mass Airflow.
By John McBride

In 1986, Ford replaced the tried and true four-barrel carburetion setup with a sequential multiple-port fuel injection system. This new EFI-equipped 302 scared the heck out of many Mustang enthusiasts, but offered improved driveability, fuel mileage, and smooth performance. And while Ford hadn't quite worked the bugs out for hot rodders wanting to bolt on intake manifolds, heads, and some lumpy cams, the future would eventually be bright for EFI.

Any radical modifications made to the speed density engine causes the said system to go "full tilt" (in pinball or poker terms) because the load/fuel mixture tables are inflexibly burned into the processor. If you exceed these parameters by installing a cam that's too big, or an induction that flows too much, then the system can no longer effectively compute injector pulse width (fuel/air ratio) and timing. The net result is a loss of driveability, an overly rich condition, or in extreme cases, engine failure due to detonation caused by lean mixtures and/or over-advanced timing.

Like most 5.0L fanatics, your author just can't leave it stock. I already have a pretty wicked '85 Mustang LX Coupe getting ready to be reassembled and I bought this particular '88 GT to be used as a daily driver. A promise to my wife to leave it stock turned into "it's just a couple of modifications, honey..." Married guys with Mustangs, you know the look that follows!

I knew that my '88 GT was a speed density car when I bought it, but now that I've started modifying it, I can't stop. I also know that before you can add any real performance modifications beyond cold-air intakes, gears, and exhaust on a '86-'88 speed-density-equipped 5.0L Mustang, you have to convert to mass airflow.

So here we are doing a mass air conversion on my Mustang. But first let's take a look at the difference between speed density and mass airflow. 

Speed Density vs. Mass AirFlow
With a speed density system, actual intake manifold pressure is now measured using a manifold absolute pressure (MAP) sensor, as well as inlet air temperature (IAT), and in addition to the previously sensed TPS and engine rpm. Now the ECU fuel control programming includes a desired air/fuel ratio table, the injector flow rates, engine cubic inch displacement, a volumetric efficiency table, and the programs necessary to instantaneously calculate inlet airflow, required fuel flow (for the desired A/F ratio found in the A/F ratio table), and finally the correct injector pulse width.

With mass airflow, the air entering the engine is actually measured using a mass airflow (MAF) sensor. Injector pulse width is still calculated in the same manner as shown previously, however, now the airflow is actually measured instead of calculated. In a sense, things happen before the fact, rather than after the fact. The big advantage of a MAF system is that you can change things on the engine that affect airflow and maintain driveability. In most cases, the MAF sensor will realize the change in airflow, and the fueling will still be correct. It makes the MAF system the most forgiving for engine modifications.

The first thing I did before buying any parts for my conversion was to do research. I decided I didn't want to waste time trying to scrounge parts from various salvage yards and hope I had everything I needed to complete my conversion.

 

MUSCLE MUSTANGS

                     & FAST FORDS

Below you will find an exert from our featured article, in the October 2009 issue of MUSCLE MUSTANGS & FAST FORDS, intitled "Mass Appeal".  You can view the full article online at

Be sure to also check out the Throttle Position Sensor (TPS) Calibration Kit, avaliable for 1986-93 Mustangs, which was tested in the same article.  You can access this portion of the article at