REF: DRAW-THRU MAF vs BLOW-THRU MAF

On my P1SC setup, during installation, we had to relocate the MAF down towards the air filter, and had to add about 2 feet of wire for this extension.

1) Does the MAF convert the analog signals to digital and then send the digital readings to the PCM or does the MAF send analog signals to the PCM for conversion and translation?

2) If the MAF sends an Analog signal, does the increased distance and connections, add any significant impedance and potentially distort signals? Is the wire distance (MAF to PCM) considered as a modifier in the signal?

 

I don't think the wire length makes a big difference but the connections do. Just check that there is not much resistance in the wires after they are soldered. The O2 sensors are the ones that you don't want to mess with the wiring because the voltages are so low (~450 mv). Or you could just move the MAF to the pressure side and you would not have to cut or splice any wires.

 

>I have my near my air filter (more room)

 

I appreciate the responses, but neither one answers the questions. Does anybody know if the MAF is sending analog or digital signals to the PCM?

 

neither, its sending voltage readings

 

Now I'm confused. It's obvious that any signal (analog or digital) requires voltage and amperage, but the MAF table specifically compares frequency from the Mass Air Sensor and x-ref's to Air flow/Grams per second. How is that a voltage reading? Are you inferring that the MAF converts frequency to voltage? What level of voltage are you referring to? (12V, -5v, .25mv?)

 

I believe it's an analog signal. The distance of wire is too short to matter. I'd just use the same guage wire as an extension and be sure that the connection points are solid and weatherproof.
If you just twist the wires together and use electrical tape to cover, water can get to the bare wires and corrossion could occur which would then change the overall impedance. Use solder or some weathertight crimp connections.

 

I had an O-Scope on the MAF output and it is a square wave output, so I guess you can call it digital. The PCM is analysing the frequency of this digital output from the MAF. The amplitude does not change with an increase in airflow, just the frequency.

Bill

 

Bingo.

So as long as the signal (sq wave) gets to the PCM, it should be fine.

What kinda levels did it emit?

 

I believe it was a 5 Volt square wave. It's been a while since I did that test, I was going to build a frequency divider to prevent the MAF from Maxing out. I had the circuit built, and thought if I halfed it, I would just half the injector size inputted in the PCM and it would have ran. I figured that the PCM would see the airflow cut in half, but it would have thought the injectors were smaller than actual so it would have shot almost the correct amount of fuel in. Tuning obviously required, but that was the thought. I never even plotted the Freq vs airflow to see if it was a linear relationship, if it wasn't some changes to the MAF table would be required.

Bill