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-   -   can't make heads or tails of these numbers(stft and ltft) (https://maxima.org/forums/all-motor/666620-cant-make-heads-tails-these-numbers-stft-ltft.html)

Mr. Blue Sky 06-04-2013 10:11 PM

can't make heads or tails of these numbers(stft and ltft)
 
Ok, car (2000 auto, 193k) has been having an intermittent P0134 issue, so I decided to check some parameters using the obd2 scanner I have that shows some live data.
they are as follows(car was warmed up to normal operating temp):

idle (750rpm)
STFT B1 (%): ranges from 6-10.1
LTFT B1 (%): 9.3
STFT B2(%): 6-10.1
LTFT B2 (%): 9.3

o2 B1S1 voltage: ranges from .030 to 0.890v
O2 B1S1 STFT: ranges from 6-15%
O2 B1S2 Voltage: 0.291 stable
O2 B1S2 STFT :N/A

1500 RPM


STFT B1 (%): ranges from 14.7-23
LTFT B1 (%): 9.3
STFT B2(%): 12.5-22
LTFT B2 (%): 9.3

o2 B1S1 voltage: ranges from .080 to 0.740v
O2 B1S1 STFT: ranges from -1.5 TO 18%
O2 B1S2 Voltage: 0.291 stable
O2 B1S2 STFT :N/A

2500rpm


STFT B1 (%): ranges from -2.3 - 3.0
LTFT B1 (%): 8.5 - 9.3
STFT B2(%): 0 - 8
LTFT B2 (%): 9.3

o2 B1S1 voltage: ranges from .080 to 0.770v
O2 B1S1 STFT: ranges from -3.1 TO 3.1%
O2 B1S2 Voltage: 0.300 stable
O2 B1S2 STFT :N/A

From what I can tell, most of the time it is adding fuel since it senses a lean condition(heard it was normal as long as it is less than 5%). What worries me is that I have heard around +/- 5% is the normal range, and mine is above that.

It runs a bit rough when at idle(a slight bit lopey) and it stutters when first giving it gas(if you give it a slight bit of gas, not WOT). Don't have data logging capabilities, so I don't know how those numbers change at WOT, or at any point in the drive. I know what I am looking for is kind of vague, but was just wondering if these numbers show anything obviously wrong that would cause my issues or not. thanks for any help that you can give.


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