Mass air flow ?

[jonlabree]

Stupid question #1. Which wire at the mass air flow sensor on the throttle body can you get the output voltage reading?

[jonlabree]

Bump Please??

[jonlabree]

NO one knows?????

[D-a-n-i-e-l]

The yellow or pin "A" is the output signal to the ECM. Black or "C" is ground. And pink/black or "B" is ACC.

[jonlabree]

Thanks Daniel. I wasn't sure about it.

I was supprised that no one else knew which one it was.

For a repy, next I was going to ask with multiple choice

A, B, or C.

Thanks again

Jon...

[2seater]

The MAF output to the ECM is frequency based. The maximum frequency is 10.4kHz, or 170 grams per second. I have a chart of the frequencies vs airflow around somewhere.

[2seater]

I used a Radio Shack VOM with frequency capabilty to test MAF's on my flowbench. This is the chart I mentioned.

Hal, here is a list of Hitachi MAF sensor flow rates GM assigned the MAF sensor output frequency in a stock 3800 vin C chip...

MAF Vs. Output Frequency Table 1

kHz gm/sec

2.00 3.19

2.13 3.53

2.26 3.94

2.39 4.38

2.52 4.81

2.66 5.31

2.79 5.88

2.92 6.41

3.05 6.97

MAF Vs. Output Frequency Table 2

kHz gm/sec

3.05 7.44

3.18 8.06

3.31 8.81

3.44 9.56

3.58 10.31

3.71 11.31

3.83 12.50

3.97 13.69

4.10 14.88

MAF Vs. Output Frequency Table 3

kHz gm/sec

4.10 13.9

4.23 15.1

4.36 16.5

4.49 17.9

4.63 19.3

4.76 20.8

4.89 22.4

5.02 23.9

5.15 25.4

MAF Vs. Output Frequency Table 4

kHz gm/sec

5.15 25.43

5.28 27.07

5.41 28.55

5.54 30.19

5.68 32.16

5.81 34.13

5.94 36.09

6.07 38.23

6.20 40.20

MAF Vs. Output Frequency Table 5

kHz gm/sec.

6.20 41.00

6.33 43.25

6.46 45.75

6.59 48.25

6.73 50.75

6.86 53.75

6.99 56.50

7.12 59.50

7.25 62.75

MAF Vs. Output Frequency Table 6

kHz gm/sec

7.25 62.5

7.38 65.8

7.51 69.4

7.64 72.7

7.78 76.3

7.91 79.6

8.04 83.2

8.17 87.2

8.30 91.2

MAF Vs. Output Frequency Table 7

kHz gm/sec

8.30 91.2

8.43 95.2

8.56 99.3

8.69 103.3

8.83 107.8

8.96 112.4

9.09 117.4

9.22 121.9

9.35 127.0

MAF Vs. Output Frequency Table 8

kHz gm/sec

9.35 126.3

9.48 131.0

9.61 136.4

9.74 141.8

9.88 147.1

10.00 153.2

10.14 158.6

10.27 164.6

10.40 170.0

[D-a-n-i-e-l]

That is great info. Do yoiu do your own tuning?

[2seater]

The information came from Ryan of GM Tuners. The remote MAF's from the 3400 (3") and the 3.5" LT1 MAF's use the same frequency range so our ECM can read the full range, although the air flow at the same frequency is different, of course. I ran a comparison between the 3" MAF and the stock Hitachi MAF from the vin C for Ryan and the flow rate is almost exactly 1.5:1, actually about 1.52 as much air flow, which is a good match for most moderately boosted stock engines.

[D-a-n-i-e-l]

That is great info and I may use it when I do my final tune