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I'm hoping to do some dataloging and tuning on a carby vehicle with Innovate Motorsport products (so far LM2, LMA3-AuxBox, SSI-4, and Pocket Logger). The Innovate LMA3 has an inbuilt MAP sensor but I would like to attach a MAF and do some dataloging with it as well. My problem is I don't have any specs on 0-5 volts to airflow values for any commonly available MAFs. The vehicle I want to datalog is a genuine HDT VC Commodore so I'm pretty sure MAFs from engines like the V6 Ecotec, HSV V8, LS would be sufficient but if we can create a list of MAF values so that others can use the information it would be good.
There are two problems you're going to face. Firstly many MAF sensors (and particular many from GM) don't use a 0-5V output but instead use a frequency output. The second problem is that you'll then need a conversion from voltage or frequency to airflow which will differ for each MAF sensor so it's perhaps not as straightforward as it first seems.
Thanks Andre for your reply.
So thinking about frequency output are you saying an ecotec V6 MAF isn't standardised so you can swap 1 for another and it will be not be ok, or are you saying an ecotec V6 MAF isn't the same as an LS1 MAF. If it's the 2nd then I am aware of that and thus the reason why I think it would be a good thing if we can list MAF values for each MAF used on popular vehicles.
Most Japanese cars use 0-5V style MAF sensors. You might be able to find scaling data from Subaru or Mitsubishi open-source reflash tools. The trouble with MAF sensors is they detect the mass flow through the little sensing element, which will depend on the intake piping the sensor is mounted in. Even changing from an OEM intake to aftermarket airbox (without changing pipe diameter) can be enough to interfere with the normal short- and long-term fuel trims on a factory ECU. If you only need to measure flow gains or losses, having the raw voltage should still be helpful.
Thanks Scott. You're correct, and it shows I have over analysed things, having the raw voltage output should still be helpful. As long as I can see changes I don't actually need to know what the airflow is just that there is a change in airflow. Being a non electronic carby (Rochestor Quadrajet) the MAF won't have any effect on an ECU so there is no need to be overly concerned about changes to the intake track. All that is really needed is the raw voltage output. Thanks again.
Careful if you're using the MAF sensor to test changes to the intake piping design. The sensor isn't aware of the pipe diameter it's installed in, so the same MAF sensor installed in two different diameter pipes will register different voltages even if the total airflow in the system is unchanged due to a restriction elsewhere. Simply moving the sensor's mounting location near a bend can change the sensor voltage due to localized changes in air speed. The MAF sensor should still be useful for evaluating changes far upstream or downstream of where the sensor is located, especially if you can get some baseline MAF data from a dyno to get a feel for how the sensor voltage correlates to horsepower.
The purpose of the exercise is to fine tune an already tuned system. Quadrajets are a great carb and with their APT (adjustable part throttle) it is possible to get extremely good mpg. Knowing how much air is flowing in enables the tuner to select the main jets for full power but also more appropriate metering rods for cruise AFR ratios.