So tomorrow I'm going to look at an '88 GT. It has a cobra intake and bbk exhaust and the owner says it has a roller cam. There's no way to directly verify the cam, but I know that pre-89 Mustangs use speed density which won't work with anything other than the stock cam. So I figure if it doesn't have a MAF conversion, the motor will have problems or he's just lying. Here's my problem, I can't tell the difference between a speed density sensor and a MAF, and i can't seem to find any helpful pictures, so I need to figure out what to look for to figure out which system it has. If anyone can explain how to tell them apart or has pictures that would be great. Thanks!
Speed Density And Maf
- Thread starter dreadnaught156
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jcyamaharider
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- Dec 24, 2014
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Been a long time since I have worked on my older 5.0's but the speed density cars don't have anything on the air intake track. If there is a short section of tube that has an electrical plug, after the air filter up to the throttle body, so to speak, this is your MAF, and would not be a speed density car.
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jcyamaharider
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f8tlfiveo
My wife likes my spool and blow-off valve.
^^^ what they said. Also depending on the cam profile speed density can still work. MAF is better if you're planning on anything more aggressive.
Speed Density uses Manifold vacuum (MAP), Throttle position (TPS) and RPM, & Air Temperature (ACT) to guess how much air the engine is pulling in. Then it uses all of them plus the O2 and ECT sensors to calculate the air/fuel mixture. It is dependent on steady manifold vacuum and minimal changes in airflow from the stock engine configuration to maintain the proper air/fuel ratio. Change the airflow or vacuum too much and the computer can't compensate for the changes, and does not run well. Forget about putting a supercharger, turbocharger or monster stroker crank in a Speed Density engine, because the stock computer tune won’t easily handle it. Every time you seriously change the airflow through the engine, you need a new custom burned chip to make the engine run at peak performance.
Mass Air uses a Mass Air Flow meter (MAF) to actually measure how much air is being pulled into the engine. The computer uses the MAF sensor data information and inputs from the O2, TPS, ACT, ECT, RPM and Barometric Pressure (Baro) sensors to calculate the proper air/fuel ratio. It is very tolerant of changes in airflow and vacuum and tolerates wild cams, high flowing heads, and changes in displacement with minimal difficulties. Larger injectors can be used with an aftermarket calibrated MAF or with the best solution, a custom dyno tune. This makes it possible to use the stock computer with engine displacements from 302-408 cu in, and make modifications without a custom dyno tune chip. Put a new intake manifold on your 331 stroker and the computer figures out how much more fuel to deliver without having to have a new chip burned to accommodate the extra airflow.
Picture of a MAF - yours may be slightly different.
Mass Air uses a Mass Air Flow meter (MAF) to actually measure how much air is being pulled into the engine. The computer uses the MAF sensor data information and inputs from the O2, TPS, ACT, ECT, RPM and Barometric Pressure (Baro) sensors to calculate the proper air/fuel ratio. It is very tolerant of changes in airflow and vacuum and tolerates wild cams, high flowing heads, and changes in displacement with minimal difficulties. Larger injectors can be used with an aftermarket calibrated MAF or with the best solution, a custom dyno tune. This makes it possible to use the stock computer with engine displacements from 302-408 cu in, and make modifications without a custom dyno tune chip. Put a new intake manifold on your 331 stroker and the computer figures out how much more fuel to deliver without having to have a new chip burned to accommodate the extra airflow.
Picture of a MAF - yours may be slightly different.
Mustangs have had roller cams since 1985. That doesn't mean the camshaft is aftermarket. Could be the stock cam.
mikestang63
SN Certified Technician
Most major cam companies make SD specific cams. I ran a Crane cam, larger TB, headers, exhaust, intake and Edelbrock heads all on SD with a Chris Johnson chip with no issues . The problems come when you run a big cam or power adder.
