cramey

I've been noticing slightly worse gas mileage and very sluggish starts from 0-20mph under normal acceleration. I started reading about MAFs and O2 sensors and I think I may have a problem with either.

I ran VAG-COM on block 003 and it read about 6.5g/s at idle... from what I've read that might be a bit high?

I have a 99 A4 1.8T Tip AEB with a GIAC chip. Any suggestions on what else I can diagnose?

Any help would be much appreciated!

Nate (ETKA+Scumbag)

When is the last time you changed your spark plugs? What air filter do you have?

cramey

I changed the plugs around 15-20k miles ago, and as I mentioned in the subject I haven't done a logging WOT test yet to measure other things.

I have just a stock replacement air filter I got at the local auto store...

Nate (ETKA+Scumbag)

nasty, and do logging at WOT.

O₂ sensors are easy enough to do on the four banger and you only need one! Remanned MAFs run around $120 IIRC and oxygen sensors are right around that price too from autohausaz.com.

cramey

Here is what I got... Couple WOT to redline, or whenever the TIP shifted...
<pre>
Group A: '003
Engine Air Throttle Ignition
TIME Speed Mass Flow Angle Timing
Marker STAMP /min g/s ° °BTDC
60.48 840 5.76 7.4 12.8
60.84 840 5.69 7.4 14.3
61.22 800 10.28 28.2 6
61.59 1440 19.51 40.4 15
61.98 1640 24.09 48.2 12
62.34 1720 27.5 51.2 9
62.73 2000 35.34 56.9 9
63.1 2200 43.4 58.2 6.8
63.48 2400 49.51 59 6
63.85 2680 62.08 76.4 6
64.22 3120 95.69 87.2 3.8
64.6 3600 104.72 87.2 9
64.98 4120 118.61 87.2 12.8
65.37 4640 124.72 87.2 16.5
65.75 5200 136.25 87.2 18
66.14 5680 141.25 87.2 20.3
66.5 6080 145.21 87.2 18
66.89 6120 144.65 87.2 3
67.27 4280 132.36 87.2 3
67.66 4160 113.19 87.2 12
68.04 4400 125.21 87.2 12
68.41 4520 127.84 87.2 10.5
68.79 4720 129.37 87.2 12
69.16 4880 134.86 87.2 17.3
69.56 5080 137.84 87.2 18.8
69.94 5240 140.21 87.2 15.8
70.33 5400 143.47 87.2 16.5
70.71 5560 144.93 87.2 12
71.08 5680 146.32 87.2 14.3
71.51 5840 147.5 87.2 13.5
71.88 5960 148.4 87.2 14.3
72.28 6080 148.33 87.2 12.8
72.66 6200 149.03 87.2 15
73.03 6120 147.01 87.2 0
73.42 4640 136.94 87.2 5.3
73.78 4720 99.72 30.4 15
74.15 4320 14.17 16.1 37.5
74.52 4080 11.32 13 37.5
74.9 3720 9.37 10.9 37.5
75.29 3240 7.84 9.5 35.3
75.67 2840 6.81 7.4 32.3
76.05 2960 5.83 6.5 33
76.42 2880 5.48 6.5 32.3
76.82 2840 5.42 6.1 32.3
77.19 2800 5.14 5.6 31.5
77.56 2760 4.93 5.6 31.5
77.96 2680 4.79 5.6 30.8
78.34 2640 4.51 5.2 30.8
78.73 2560 4.37 4.8 30
79.09 2440 4.23 4.8 29.3
79.48 2400 4.03 4.8 29.3
79.84 2280 4.23 4.8 28.5
80.23 2240 3.96 4.3 27.8
80.6 2160 3.82 4.3 27.8
80.98 2080 3.61 3.9 27
81.36 2000 3.47 3.9 27
81.75 1960 3.26 3.5 26.3
82.13 2000 12.78 18.2 26.3
82.5 2120 17.43 5.2 33.8
82.89 1920 4.44 3.9 26.3
83.27 1720 3.26 3.5 24.8
83.64 1760 2.64 2.6 25.5
84.02 1680 2.78 2.6 24.8
84.39 1560 2.57 2.6 24
84.77 1440 2.5 2.6 23.3
85.14 1320 2.64 3 20.3
85.52 1200 2.84 3.5 5.3
85.89 1400 3.12 3.5 5.3
86.26 1400 3.26 4.3 5.3
86.63 1240 3.61 4.8 4.5
87.01 1040 3.82 6.1 12.8
87.4 960 4.17 5.6 12
87.8 920 4.44 6.1 12
88.18 960 4.86 6.5 12
88.55 1000 5 6.5 12
88.93 1000 5 6.5 12
89.32 1040 6.11 9.5 13.5
89.7 1160 11.04 19.1 3.8
90.08 1640 20.07 28.2 23.3
90.45 1880 26.87 41.2 15
90.84 2000 32.57 43.4 12
91.22 2120 37.84 53.8 9
91.61 2280 45.14 67.3 6
91.97 2360 54.51 81.2 3
92.34 2480 66.81 81.2 2.3
92.72 2720 86.94 80.7 0.8
93.11 2880 89.03 80.3 2.3
93.49 2960 92.29 80.3 3
93.86 3120 97.01 80.3 3.8
94.23 3320 102.5 80.3 5.3
94.6 3480 107.22 80.3 7.5
94.98 3640 109.79 80.3 9
95.36 3840 112.29 80.3 10.5
95.75 4040 116.81 79 12
96.15 4240 123.89 78.6 12
96.52 4440 125.48 78.1 14.3
96.9 4600 129.72 84.6 13.5
97.28 4800 132.78 87.2 12
97.67 5000 137.84 86.8 13.5
98.05 5160 140 86.8 18.8
98.42 5320 143.19 86.8 12.8
98.8 5480 144.37 78.6 15
99.17 5600 143.68 57.3 12
99.55 4240 81.11 35.6 16.5
</pre>

Nate (ETKA+Scumbag)

Yeah, I don't think your MAF is reading right. My peak is 171.73 g/s with APR 1 bar sofware.

cramey

Or just get a new one?

I also have a o2 sensor i need to throw in but my o2 wrench bent trying to replace the one i have in there :\

Nate (ETKA+Scumbag)

As for getting the O2 sensor out, I used a 22mm wrench and got it by removing the airbox so I could get leverage.

Use some PB Blaster on it, tap it with a hammer, add some more PB, let it soak, and give it a twist.