surging when accelerating on right turns

[Craig 94 TA GT]

I noticed that the car to hesitates/jerks when accelerating on right turns. At first I thought it was my rear end giving out (which it is, but may be unrelated to the problem). But now I realize that it may be the motor surging. It does this only once in a while on left turns. I did 2 scans when it does this and notice horrible MAF readings. There is a wire to the MAF that may be making intermittent contact when there's a specific G-force applied to the car. Maybe it's the problem, or maybe there's something else I'm missing, or causing the bad MAF readings? It does this during open and closed loop. Can anybody please verify with these scans? I believe it was in open loop.

http://s94938520.onlinehome.us/data/right_turn1.csv

http://s94938520.onlinehome.us/data/right_turn2.csv

Maybe I'll try unplugging the MAF to see if this continues.

[LS1 TA]

This may sound kinda dumb, but I myself have over looked the obvious on more than one occasion. How low was your fuel tank when accelerating around the corner?

[Craig 94 TA GT]

About 3/4 full.

[LS1 TA]

About 3/4 full.

I figured you were good on that, just figured I'd ask just in case. One time I changed my fuel pump because it wouldn't prime when you turned the key. I checked the fuse to it and it was good. I dropped the tank, also 3/4 full, and replaced the pump, turned the key, and nothing. It was the fusable link between the battery and the ECM.

[fastTa]

Considering 10 frames per second, I don't really put much faith into the o2 voltages and especially with a short part throttle scan. But, just based on that short scan you posted, your bank 2 average was 0.704 and your bank 1 average was 0.392. Bank one average shows a bit lean but not too bad considering the load and RPM, and bank 2 appears to be a bit rich given the load and RPM.

The PCM is barely adding fuel on bank 1(2.3%) for the long term corrections which would appear to be consistant with the low bank 1 o2 voltage average. The PCM does use o2 voltage averages for certain lookups, but because of the inherant and inevadable delay in doing so, I wouldn't put much faith in o2 voltage averages either.

You are going into cell 18 as soon as you break 0% TPS. It's hard to make an assumption based off this short part throttle run, but let's say you're under a significant load or approaching PE and the intergrators were to hold steady and you were still in cell 18.... that would be something to look at.

[Joe 1320]

Pssst......




Craig.......




It's an easy fix.......













Turn LEFT. That's all the Nascar boys do.

[Craig 94 TA GT]

Kevin, thanks for the reply. What do you get out of reading the narrowband O2 readings? Can you see a general mixture? I originally didn't think anything of the O2 because this problem occurs regardless of open/closed loop...which is why I was in open loop when the readings occurred. Is there a way of reading the A/F ratio by reading the O2s? What range is typically 14.7:1?

The main thing that concerned me was the readings of the MAF. I know it will sometimes spit out a funny reading, but by this much? The left column is speed and MAF readings.



Joe, if I were to only make left turns, I'd be driving a Cup car. Hey, I wouldn't mind! Really!

[fastTa]

That's obviously a GPS graph and those sharp down spikes definitely look like the MAF is intermittantly shorting, losing power or losing ground. Check the pink wire, it should have 12V. The black/white wire is a ground. Make sure it is grounded well. I belive the yellow wire should get 5V.

For what it's worth, my hot wire(pink) on my MAF split apart right by the MAF sensor and caused similar problems to what you are describing. Once I got it resoldered, my intermittent miss went away.

[Craig 94 TA GT]

Thanks Kev. Very interesting situation you had...and seems identical to mine. I do have a slight miss every so often, and it has shown up as a huge problem on right turns now. So I'm assuming that they're of the same problem.

I repositioned the wiring today and it did not do the surge/miss anymore. So I'm assuming that it is the problem. I'll take your advice and resolder it.

BTW, on reading O2s, the higher the voltage, the more air it reads? Can you take the average of set of values over time to estimate the A/F ratio?

[fastTa]

Thanks Kev. Very interesting situation you had...and seems identical to mine. I do have a slight miss every so often, and it has shown up as a huge problem on right turns now. So I'm assuming that they're of the same problem.

I repositioned the wiring today and it did not do the surge/miss anymore. So I'm assuming that it is the problem. I'll take your advice and resolder it.

BTW, on reading O2s, the higher the voltage, the more air it reads? Can you take the average of set of values over time to estimate the A/F ratio?

The way an O2 sensor is designed, oxygen is an inhibitor to creating voltage. The more oxygen going across the sensor, the lower the voltage. The less the oxygen the higher the voltage.

That's why the PCM interprets a higher voltage (.500V or higher) as a rich condition, and a lower voltage (.400V or lower) as a lean condition.

[fastTa]

BTW, if you want to test the calibration of your MAF. Here are the following frequency and flow relationships:

Hz Airflow(GPS)
1,488 2.45
1,616 2.88
1,744 3.34
1,872 3.87
2,000 4.45
2,128 5.12
2,256 5.85
2,384 6.64
2,512 7.49
2,640 8.41
2,768 9.4
2,896 10.46
3,024 11.6
3,152 12.82
3,280 14.11
3,408 15.48
3,536 16.98
3,664 18.6
3,792 20.34
3,920 22.22
4,048 24.23
4,176 26.35
4,304 28.6
4,432 30.97
4,560 33.43
4,688 35.99
4,816 38.69
4,944 41.54
5,072 44.52
5,200 47.66
5,328 50.97
5,456 54.42
5,584 58.04
5,712 61.81
5,840 65.77
5,968 69.92
6,096 74.27
6,224 78.82
6,352 83.59
6,480 88.58
6,608 93.8
6,736 99.25
6,864 104.93
6,992 110.88
7,120 117.04
7,248 123.42
7,376 130.03
7,504 136.88
7,632 143.92
7,760 151.14
7,888 158.63
8,016 166.31
8,144 174.03
8,272 182.36
8,400 191.01
8,528 200.07
8,656 209.43
8,784 219.12
8,912 229.15
9,040 239.52
9,168 250.23
9,296 261.3
9,424 272.71
9,552 284.48
9,680 296.61
9,808 309.1
9,936 321.96
10,064 335.2
10,192 348.8
10,320 362.77
10,448 377.14
10,576 391.88
10,704 407.02
10,832 422.55
10,960 438.46
11,088 454.78
11,216 471.51