Quote:
Originally Posted by supramacist
GO back to chevy.
You have no business with one of these cars.
Especially if you aren't smart enough to know to not toy with afm.
DUH. |
That's uncalled for. Give the guy some credit, he at least got information from someone who he thought knew what he was talking about.
Now, Mr. Sold my Malibu,
In the world of EFI there are several different systems used for measuring airflow: VAF, KVAF, MAF and MAP/IAT (aka Speed Density).
VAF = Vane Air Flow meters use a flap placed in the airflow. Incoming air pushes the flap out of the way and in doing so moves a variable resistance wiper, thus scaling the voltage returned to the ECU. The non-turbo MKIII uses this system. It's the most restrictive system out there, not very accurate, but also one of the harder ones to f@#% up.
KVAF = Karmen Vortex Air Flow meters use a honeycomb shaped grill to form the airflow into a specific pattern. This patterned airflow is then read by an array of optics. The data about the amount of air is then returned to the ECU as a pulsed signal. This is probably the easiest system out there to screw up in a MAJOR way. Solvents can ruin the lenses the optical sensor looks through or they may enter the electronics housing and destroy the optical element itself. In SOME cases people have managed to dissect, clean and rebuild the damaged housing... but usually, once it's shot you're going to have a much easier time shopping for a used replacement.
MAF = Mass Air Flow sensors (most commonly GM's hot wire type) are robust, fairly accurate (not as accurate as the KVAF, but much more than the VAF) and less restrictive than either of the previous systems. They are susceptible to damage from solvents or oils (as are the KVAF).
MAP/IAT (Speed/Density) = Manifold Air Pressure and Intake Air Temp are measured with two separate sensors. Manifold pressure is measured via nothing more than a vacuum source supplied by the manifold and the temperature sensor is the ONLY obstruction in the intake path. This system is as unrestrictive as you get and arguably more robust than all three of the aforementioned systems.
There are electronics out there which will allow you to convert from one system to the next. These setups are not cheap, but once in place replacing the components of some is far less expensive than others (KVAF is probably the most expensive to replace).
Unfortunately, you learned about the frailties of the KVAF the hard way. In the future you may want to seek another opinion before using solvents on sensors.
Best of luck with the car!
Oh, and by the way, you may hear of the MKIII's meter referred to as the AFM. This is a generic term used for all of the different meters used by Toyota. It simply means "Air Flow Meter" but is nondescript and provides no information as to what type of meter you're referring to. As such it doesn't hurt to mention what type of meter or whether it's on a turbo or nonturbo model.